Description
Service principal names (SPNs) are used to uniquely identify each instance of a Windows service. To enable authentication, Kerberos requires that SPNs be associated with at least one service logon account (an account specifically tasked with running a service (Citation: Microsoft Detecting Kerberoasting Feb 2018)). (Citation: Microsoft SPN) (Citation: Microsoft SetSPN) (Citation: SANS Attacking Kerberos Nov 2014) (Citation: Harmj0y Kerberoast Nov 2016) Adversaries possessing a valid Kerberos ticket-granting ticket (TGT) may request one or more Kerberos ticket-granting service (TGS) service tickets for any SPN from a domain controller (DC). (Citation: Empire InvokeKerberoast Oct 2016) (Citation: AdSecurity Cracking Kerberos Dec 2015) Portions of these tickets may be encrypted with the RC4 algorithm, meaning the Kerberos 5 TGS-REP etype 23 hash of the service account associated with the SPN is used as the private key and is thus vulnerable to offline [Brute Force](https://attack.mitre.org/techniques/T1110) attacks that may expose plaintext credentials. (Citation: AdSecurity Cracking Kerberos Dec 2015) (Citation: Empire InvokeKerberoast Oct 2016) (Citation: Harmj0y Kerberoast Nov 2016) This same attack could be executed using service tickets captured from network traffic. (Citation: AdSecurity Cracking Kerberos Dec 2015) Cracked hashes may enable Persistence, Privilege Escalation, and Lateral Movement via access to [Valid Accounts](https://attack.mitre.org/techniques/T1078). (Citation: SANS Attacking Kerberos Nov 2014)
Threat-Mapped Scoring
ATT&CK Kill Chain Metadata
- Tactics: credential-access
- Platforms: Windows
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Detection Guidance:
Enable Audit Kerberos Service Ticket Operations to log Kerberos TGS service ticket requests. Particularly investigate irregular patterns of activity (ex: accounts making numerous requests, Event ID 4769, within a small time frame, especially if they also request RC4 encryption [Type 0x17]). (Citation: Microsoft Detecting Kerberoasting Feb 2018) (Citation: AdSecurity Cracking Kerberos Dec 2015)