Kerberoasting simple facts

 

Prerequisites for possible attack

1. Attacker already possess an account in domain
2. Attacker has access to KDC
3. Targeted account must have SPN

 

Attack path:

1. Attacker logs in with account A
2. Attacker request TGS against account B that has SPN, using SPN to obtain ticket
3. Attacker dumps the ticket and crack it offline
4. Attacker knows password of user B

 

Prevention:

1. Strong passwords
2. Disable RC4 encryption support for Kerberos tickets (this can be done on DC side and/or user account side)
1. On DCs, use GPO to disable RC4 support “Security Options -> Network security: Configure encryption types allowed for Kerberos”
2. On user account, attribute msDS-SupportedEncryptionsTypes
3. Normal account should NOT have SPNs
4. Use gMSA so password is random and strong

 

Detection:

1. Spikes in EventID 4769 for same SPN
2. Spikes in EventID 4769 from a normal user account