Yet Another critical Flaw and Critical Patch
The flaw reported two weeks ago by a Google researcher Adam Langley and BoringSSL’s David Benjamin, affects OpenSSL 1.0.1 and 1.0.2. The flaw have been patched by OpenSSL.
OpenSSL CHANGES
Alternate chains certificate forgery
During certificate verfification, OpenSSL will attempt to find an alternative certificate chain if the first attempt to build such a chain fails. An error in the implementation of this logic can mean that an attacker could cause certain checks on untrusted certificates to be bypassed, such as the CA flag, enabling them to use a valid leaf certificate to act as a CA and “issue” an invalid certificate.
This issue was reported to OpenSSL by Adam Langley/David Benjamin
(Google/BoringSSL).
[Matt Caswell]
This issue will impact any application that verifies certificates including SSL/TLS/DTLS clients and SSL/TLS/DTLS servers using client authentication
It’s a bad bug, but only affects anyone who installed the release from June says OpenSSL development team… It’s a bad bug, but the impact is low. We haven’t heard any reports of it being used in production.
During certificate verification, OpenSSL will attempt to find an alternative certificate chain if the first attempt to build such a chain fails. An error in the implementation of this logic can mean that an attacker could use certain checks on untrusted certificates to be bypassed, such as the CA flag, enabling them to use a valid leaf certificate to act as a CA and ‘issue’ an invalid certificate.
