CWE-370: Missing Check for Certificate Revocation after Initial Check
Missing Check for Certificate Revocation after Initial Check
Weakness ID: 370 (Weakness Base)
Status: Draft
Description
Description Summary
The software does not check the revocation status of a certificate after its initial revocation check, which can cause the software to perform privileged actions even after the certificate is revoked at a later time.
Extended Description
If the revocation status of a certificate is not checked before each action that requires privileges, the system may be subject to a race condition. If a certificate is revoked after the initial check, all subsequent actions taken with the owner of the revoked certificate will lose all benefits guaranteed by the certificate. In fact, it is almost certain that the use of a revoked certificate indicates malicious activity.
Time of Introduction
Architecture and Design
Implementation
Applicable Platforms
Languages
All
Common Consequences
Scope
Effect
Access Control
Technical Impact: Gain privileges / assume
identity
Trust may be assigned to an entity who is not who it claims to
be.
Integrity
Technical Impact: Modify application
data
Data from an untrusted (and possibly malicious) source may be
integrated.
Confidentiality
Technical Impact: Read application
data
Data may be disclosed to an entity impersonating a trusted entity,
resulting in information disclosure.
Likelihood of Exploit
Medium
Demonstrative Examples
Example 1
(Bad Code)
Example Languages: C and C++
if (!(cert = SSL_get_peer(certificate(ssl)) || !host)
foo=SSL_get_verify_result(ssl);
if (X509_V_OK==foo) //do stuff
foo=SSL_get_verify_result(ssl); //do more stuff without the
check.
Potential Mitigations
Phase: Architecture and Design
Ensure that certificates are checked for revoked status before each
use of a protected resource. If the certificate is checked before each
access of a protected resource, the delay subject to a possible race
condition becomes almost negligible and significantly reduces the risk
associated with this issue.
Description
