More on Heartbleed

Original source

This is an update to my earlier post.

Cloudflare is reporting that it’s its very difficult, if not practically impossible, to steal SSL private keys with this attack.

Here’s the good news: after extensive testing on our software stack, we have been unable to successfully use Heartbleed on a vulnerable server to retrieve any private key data. Note that is not the same as saying it is impossible to use Heartbleed to get private keys. We do not yet feel comfortable saying that. However, if it is possible, it is at a minimum very hard. And, we have reason to believe based on the data structures used by OpenSSL and the modified version of NGINX that we use, that it may in fact be impossible.

The reasoning is complicated, and I suggest people read the post. What I have heard from people who actually ran the attack against a various servers is that what you get is a huge variety of cruft, ranging from indecipherable binary to useless log messages to peoples’ passwords. The variability is huge.

This xkcd comic is a very good explanation of how the vulnerability works. And this post by Dan Kaminsky is worth reading.

I have a lot to say about the human aspects of this: auditing of open-source code, how the responsible disclosure process worked in this case, the ease with which anyone could weaponize this with just a few lines of script, how we explain vulnerabilities to the public — and the role that impressive logo played in the process — and our certificate issuance and revocation process. This may be a massive computer vulnerability, but all of the interesting aspects of it are human.