CVE-2015-1793: OpenSSL Certificate Authority Impersonation

Blog Post created by todb Employee on Jul 9, 2015

On the morning of July 9, the OpenSSL Team announced the availability of a “high severity” rated patch affecting the latest version of OpenSSL 1.0.1 and 1.0.2. There was a fair amount of hand-wringing leading up to the patch availability announcement, since “high severity” is the most critical level for OpenSSL. However, it would not appear that this issue is as bad as initially feared. IT staff should prioritize OpenSSL patches against other critical business needs, and apply fixes at their most convenient opportunity.


If you're not really into reading (and who has the time?), we just put a video up covering the salient details over at Whiteboard Wednesday.

What is the issue?

According to the OpenSSL team’s advisory, the core issue is that OpenSSL can fail to correctly validate that a certificate presented is issued by a trusted Certificate Authority.

What is the impact?

In effect, the Certificate Authority mechanism for validating that endpoint services are who they say they are can be bypassed with this vulnerability. The core cryptographic procedures that protect the secrets passed between clients and servers is unaffected. So, while the encryption is unaffected, users cannot be sure who they are sharing their secrets with without the provided patch.

How can attackers leverage this vulnerability?

This vulnerability is only useful to an active attacker who is already capable of performing a man-in-the-middle (MITM) attack, either locally or upstream from the victim. This limits the feasibility of attacks to actors who are already in a privileged position on one of the hops between the client and the server, or locally on the same LAN and can impersonate DNS servers or gateway routers. In short, the vulnerability is not useful for passive attacks, or for widespread, untargeted attacks.

What is affected?

So far, it appears that only OpenSSL 1.0.1 and 1.0.2 are affected. OpenSSL 0.9.8 is not affected, nor is LibreSSL. It does not appear that any other SSL/TLS library is affected, though work is ongoing to validate this.


How does this vulnerability affect Rapid7 products?

Rapid7 products are not directly affected by these vulnerabilities.

When will Rapid7 products detect these OpenSSL vulnerabilities?

We'll be updating our product coverage to detect and validate these vulnerabilities soon, and customers will be notified of an appropriate update as soon as one is available. We'll also beupdating this blog post if there are significant changes to our understanding of this vulnerability or if other major SSL/TLS implementations are found to be affected.



On July 9, 2015, the Nexpose team put together a blog post on how to set up a Dynamic Asset Group (DAG) search to quickly assess your OpenSSL situation.