CEK-19 Key Compromise
Restrict a compromised key so that after compromise it is used only to decrypt existing data under controlled circumstances, and never to encrypt anything new.
4
artefacts
0
held by a system
2
at each review
hard
to go live
Document repository
where the evidence lives
teal = a system already holds it · olive = produced at each review
system holds itEvidence a system already holds
none for this control
periodic reviewEvidence produced at each review
- Records of compromised keys and the restriction applied · Document repository
- Technical evidence the key cannot be used for encryption · Key management / PKI
governing documentDocuments that govern the control
- The compromised key handling procedure stating the decrypt-only restriction · Policy repository / GRC workspace
- The controlled circumstances under which decryption is permitted, and who authorises it · Document repository
First move
This control is evidenced by people and documents, not systems. Put the document under version control with an owner and review date, and log each review as a record with reviewer and date. Do not try to automate it.
Common gaps auditors find
- Compromised key left fully usable while re-encryption is planned
- Restriction stated in procedure with no technical enforcement
- No record of which data still depends on the compromised key
Do this for your whole sheet
Paste the rows you run your controls from and get this mapping for every control at once, with the periodic-review ones flagged and a first move per row. No account for the first run.
Build my evidence sheet