Introduce a Revocation functionality into Kerberos eco-system.
Possible scenarios and approaches
- Support “Black list” on KDC: KDC stores information about jeopardized clients together with the timestamp when the accident was recorded (e. g. Client lost mobile phone with some active security-sensitive applications and informed KDC about it). If desired, the Application Server may get an access to this information (perhaps, through a special channel/protocol) and acts accordingly;
- Application server observes some malicious activity (e.g. through audit log analysis) and reports it to KDC. KDC acts accordingly. Ideally, the Client (person or service) is also informed (via email or some other communication channel) that his/her credentials are jeopardized;
- KDC learns that client is jeopardized or his/her credentials are changed or revoked, and dispatches warnings to all services that expressed interest in this functionality and may be potentially affected by the accident. The warning is sent only if the ticket for the particular service exists and is still valid.
- Forensics: Application server observes the malicious action. It informs KDC about the accident, but continues to serve the intruder to allow some time to track down the originator of the attack.
Lightweight approach under CAMMAC umbrella
KDC learns that client is jeopardized or his/her credentials are changed or revoked, and incorporates the revocation information into AD-CAMMAC container for every newly issued ticket.