Discovery / credits: Malvuln - malvuln.com (c) 2021 Original source: https://malvuln.com/advisory/ba815d409cd714c0eac010b5970f6408.txt Contact: malvuln13@gmail.com Media: twitter.com/malvuln Threat: Backdoor.Win32.Onalf Vulnerability: Missing Authentication Description: WinRemoteShell (Onalf) listens for commands on TCP port 2020. Interestingly, it will only start listening once it can connect outbound to SMTP port 25. Not much of a self respecting backdoor, as it allows anyone to logon without requiring a password. After logon you are greeted with Welcome to WinRemoteShell(c)Chernickevich http://onehalf.hotmail.ru. Type: PE32 MD5: ba815d409cd714c0eac010b5970f6408 Vuln ID: MVID-2021-0042 Disclosure: 01/20/2021 Exploit/PoC: TELNET x.x.x.x 2020 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).