CISA Protection of Information Assets Practice Question
An organization uses a public key infrastructure (PKI) to issue digital certificates. The IS auditor is reviewing the certificate lifecycle management. Which of the following is the GREATEST risk if certificate revocation lists (CRLs) are not updated in a timely manner?
⚠ Common exam trap
The trap is confusing revocation with expiration or signature verification; candidates may pick 'certificates may expire' or 'users may not verify signatures' when the real risk is that revoked certificates continue to be trusted.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Compromised certificates could still be used to establish trust
If CRLs are not updated in a timely manner, a certificate that has been revoked due to compromise or misuse will still appear valid to relying parties, allowing it to be used to establish trust. This defeats the purpose of revocation and can enable man-in-the-middle or impersonation attacks. Timely CRL publication is essential for the integrity of the PKI trust model.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Certificate authorities may lose their root key
Why it's wrong here
Stale CRLs leave revoked certificates trusted until expiry, so compromised keys still authenticate. Root key compromise is unrelated to CRL publication timing; that risk is mitigated by offline root key protection and hardware security modules, not by refreshing revocation data.
- ✓
Compromised certificates could still be used to establish trust
Why this is correct
CRLs are the mechanism relying parties use to learn that a certificate is revoked. If they are stale, a compromised certificate's serial number is absent, so systems continue trusting it and attackers can still authenticate or decrypt traffic until the CRL is refreshed.
- ✗
Certificates may expire without renewal
Why it's wrong here
Expiry is governed by the certificate's notAfter field and renewal processes, independent of CRL publication. Timely CRLs matter because revocation must propagate quickly; a stale list lets a revoked, possibly compromised certificate remain trusted until its natural expiry date.
- ✗
Users may not be able to verify certificate signatures
Why it's wrong here
Stale CRLs leave revoked certificates appearing valid, so relying parties may still accept them; signature verification itself uses the issuer's public key and is unaffected. CRLs exist to publish revocation status, and timely updates matter most where compromise or mis-issuance must be enforced.
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Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official ISACA exam blueprint
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