Security Experts:

Comodo Finds Misissued Certificates

Comodo admitted on Monday that it had mistakenly issued a total of eight digital certificates that did not comply with baseline requirements.

In 2011, the CA/Browser Forum adopted version 1.0 of the baseline requirements (BR) for the issuance and management of publicly-trusted certificates. One of the sections in the BR, which went into effect in July 2012, says certificate authorities (CAs) should not issue certificates with an expiry date later than November 1, 2015 with a Subject Alternative Name or Subject Common Name field containing an internal server name or IP address.

The CA/Browser Forum explained that certificates with names such as “mail” or IP addresses like, which are often used internally, can pose a serious security risk. For example, in the case of a certificate with the name “mail,” an attacker could bring such a certificate into the corporate network and use it in combination with local name spoofing to impersonate the targeted organization’s mail server and steal users’ credentials and other sensitive information.

Comodo issued a total of eight such certificates with an expiry date later than November 1. Of these eight certificates, the most risky appear to be ones with the Common Name “help” and “mailarchive.”

Rob Stradling, senior research and development scientist at Comodo, explained that the error occurred due to a code change implemented on October 30. The change was meant to automatically delete all internal names and IP addresses from a certificate request before the certificate was issued, but the change had not worked as intended due to an oversight by the developer.

The forbidden certificates were identified on November 5 and a hotfix was deployed within a couple of hours after the bug was found. All of the misissued certificates were added to the Certificate Transparency framework, whose goal is to allow domain owners to monitor the use of certificates issued for them and prevent abuse.

Stradling says Comodo has identified similar non-compliant certificates issued by other CAs as well, but details will be provided at a later time.

Recent incidents have led to major Internet companies becoming increasingly concerned about digital certificate security. The list of CAs that issued unauthorized certificates recently includes the China Internet Network Information Center (CNNIC), and Symantec, which recently admitted inappropriately issuing thousands of certificates.

Opera Software recently proposed the implementation of a requirement to get CAs to publicly disclose all incidents involving misissued certificates. The goal would be to help CAs learn from each other’s mistakes, increase transparency, and better allow users and vendors to determine how trustworthy an issuer is.

Related Reading: Mozilla Could Start Rejecting SHA1 Certificates Sooner Than Planned

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Eduard Kovacs (@EduardKovacs) is a contributing editor at SecurityWeek. He worked as a high school IT teacher for two years before starting a career in journalism as Softpedia’s security news reporter. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.