Pass the Ticket
Pass the ticket (PtT) 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 OS 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. (Citation: ADSecurity AD Kerberos Attacks) (Citation: GentilKiwi Pass the Ticket) 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). (Citation: ADSecurity AD Kerberos Attacks) 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. (Citation: Campbell 2014)
Mitigations |
|
| Mitigation | Description |
|---|---|
| Active Directory Configuration |
Configure Active Directory to prevent use of certain techniques; use SID Filtering, etc. |
| Password Policies |
Set and enforce secure password policies for accounts. |
| User Account Management |
Manage the creation, modification, use, and permissions associated to user accounts. |
| Privileged Account Management |
Manage the creation, modification, use, and permissions associated to privileged accounts, including SYSTEM and root. |
| Pass the Ticket 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. (Citation: ADSecurity AD Kerberos Attacks) 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. (Citation: CERT-EU Golden Ticket Protection) Attempt to identify and block unknown or malicious software that could be used to obtain Kerberos tickets and use them to authenticate by using whitelisting (Citation: Beechey 2010) tools, like AppLocker, (Citation: Windows Commands JPCERT) (Citation: NSA MS AppLocker) or Software Restriction Policies (Citation: Corio 2008) where appropriate. (Citation: TechNet Applocker vs SRP) |
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. (Citation: CERT-EU Golden Ticket Protection)
References
- Abolins, D., Boldea, C., Socha, K., Soria-Machado, M. (2016, April 26). Kerberos Golden Ticket Protection. Retrieved July 13, 2017.
- Campbell, C. (2014). The Secret Life of Krbtgt. Retrieved December 4, 2014.
- Deply, B. (2014, January 13). Pass the ticket. Retrieved June 2, 2016.
- Metcalf, S. (2014, November 22). Mimikatz and Active Directory Kerberos Attacks. Retrieved June 2, 2016.
Связанные риски
Каталоги
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