Pass the Ticket

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Pass the Ticket
Technique
ID T1097
Tactic Lateral Movement
Platform Windows Server 2003, Windows Server 2008, Windows Server 2012, Windows XP, Windows 7, Windows 8, Windows Server 2003 R2, Windows Server 2008 R2, Windows Server 2012 R2, Windows Vista, Windows 8.1, Windows 10
System Requirements Requires Microsoft Windows as a target system and Kerberos authentication enabled.
Data Sources Authentication logs
Contributors Ryan Becwar

Pass the ticket (PtT)1 is a method of authenticating to a system using Kerberos tickets without having access to an account's password. Kerberos authentication can be used as the first step to lateral movement to a remote system.

In this technique, valid Kerberos tickets for Valid Accounts are captured by Credential Dumping. A user's service tickets or ticket granting ticket (TGT) may be obtained, depending on the level of access. A service ticket allows for access to a particular resource, whereas a TGT can be used to request service tickets from the Ticket Granting Service (TGS) to access any resource the user has privileges to access.23

Silver Tickets can be obtained for services that use Kerberos as an authentication mechanism and are used to generate tickets to access that particular resource and the system that hosts the resource (e.g., SharePoint).2

Golden Tickets can be obtained for the domain using the Key Distribution Service account KRBTGT account NTLM hash, which enables generation of TGTs for any account in Active Directory.4

Examples

  • Some SeaDuke samples have a module to use pass the ticket with Kerberos for authentication.5

Mitigation

Monitor domains for unusual credential logons. Limit credential overlap across systems to prevent the damage of credential compromise. Ensure that local administrator accounts have complex, unique passwords. Do not allow a user to be a local administrator for multiple systems. Limit domain admin account permissions to domain controllers and limited servers. Delegate other admin functions to separate accounts.2

For containing the impact of a previously generated golden ticket, reset the built-in KRBTGT account password twice, which will invalidate any existing golden tickets that have been created with the KRBTGT hash and other Kerberos tickets derived from it.6

Attempt to identify and block unknown or malicious software that could be used to obtain Kerberos tickets and use them to authenticate by using whitelisting7 tools, like AppLocker,89 or Software Restriction Policies10 where appropriate.11

Detection

Audit all Kerberos authentication and credential use events and review for discrepancies. Unusual remote authentication events that correlate with other suspicious activity (such as writing and executing binaries) may indicate malicious activity.

Event ID 4769 is generated on the Domain Controller when using a golden ticket after the KRBTGT password has been reset twice, as mentioned in the mitigation section. The status code 0x1F indicates the action has failed due to "Integrity check on decrypted field failed" and indicates misuse by a previously invalidated golden ticket.6