For two years there was a leak in certain versions of the OpenSSL stack that made it possible to intercept traffic that was supposed to be encrypted. Even worse, there are rumors this leak made it possible to read the private key of the server. If this is really the case, this is nothing short of a meltdown of global security. In any case, it's definitively an epidemic failure. The effects of this will continue to ripple through the system for the coming weeks. Brace for more news.

Starting back with pbxnsip, security was a focus of ours from the first days we were working on our PBX. It would have been easy to use OpenSSL, since it would have had the advantage of making it so we could be FIPS certified quite easily, but there were drawbacks with OpenSSL. Our main concern was memory fragmentation - OpenSSL was allocating memory that can't be moved by garbage collection. Our PBX was designed to run for a very long time, and this comes to bear on memory allocation. Using C-style pointers makes this goal hard to achieve.

As a side effect, we used a buffer class wrapper that was protecting the code from accessing memory, outside of the allocated memory, for a variable. That was exactly what happened in the Heartbleed bug; if someone sent an index out of the boundaries of the memory allocated for the request, the OpenSSL code didn't properly check if the index is within boundaries and revealing private information.

With open source, a lot of people can take a look if the code works correctly and see if there are backdoors in the code; in this case it didn't help. I'm afraid it actually made things worse. It could well be programmers who found the bug in OpenSSL code didn't report the problem - they instead joined the dark side and exploited it. Giving the bad people the source code of such a critical component of the Internet had a disastrous effect. This explains why we had so much news about stolen passwords recently, and nobody had a good explanation for how this could happen.

I am not even sure if we need to count the people working for NSA and other government agencies around the world as bad guys. If we assume they knew about the vulnerability for some time, not telling the public about the problem for sure gave them an advantage in accessing information that would otherwise be inaccessible. If that’s the case, however, they accepted the huge collateral damage of other actors continuing to exploit the vulnerability, which is, in my opinion, unacceptable.

The main advantage of the Vodia PBX using its own TLS implementation is simply that it's not mainstream, which keeps it relatively safe from epidemic failures. Although we don’t know it, we can assume that implementation isn't free from errors, but programmers who think about attacking the PBX don’t have the source code to find open doors. Getting in without the code is difficult. It's definitively not low-hanging fruit.