How Heartbleed Leaked Private Keys

http://blog.cloudflare.com/searching-for-the-prime-suspect-how-heartbleed-leaked-private-keys

by jgrahamc • 12 years ago

99 26 12 years ago

blog.cloudflare.com

yread2• 12 years ago

I am still surprised there is code like

      if(b->d) OPENSSL_free(b->d);

in OpenSSL :(

pyvpx• 12 years ago

some folks much smarter than I thought it best to proverbially take it out back and shoot it. if you're not familiar with it already, the left overs are called LibreSSL.

endgame• 12 years ago

And if you want to watch the carnage, the highlights are at http://opensslrampage.org/ .

bbwharris2• 12 years ago

Forgive me for asking but what is wrong in particular with this single line?

To me it reads fine and the idea is that is frees that data address if its occupied. I'm sure I'm not the only one who is curious why this is bad.

yread2• 12 years ago

My concerns are well addressed in the patch:

           if (b->d != NULL)
           {

patrickas• 12 years ago

The sensitive data that was saved in that address is still there. Memory has been freed so the os can use is again but the actual data is still there is memory untill get get overwritten by something else...

The program will work with no problems, but sensitive data that has been used then freed is available for retrieval when bugs like heartbleed are found.

As the article suggests the right way is to clean the data from memory ( by overwriting it with something else) before freeing it.

syncsynchalt• 12 years ago

For one, free() is a no-op on a null.

junto• 12 years ago

Every time I see a blog post from the Cloudflare team I am impressed.

It isn't just their attention to detail that is impressive. They go out of their way not just to point out issue, but suggest fixes.

Too many Heartbleed blog posts from across the blogosphere, and sadly, HN comments, set out to criticize without suggesting something better.

Cloudflare has shown again that they are actively engaging the community for the communities benefit as well as their own.

This seems to be a very effective marketing strategy (I assume it is anyway).

ibmthrowaway2182• 12 years ago

I would have been more impressed had their original assessment of heartbleed (on nginx) not been "We've reviewed the code and we don't think it's vulnerable."

Looking impressive with hindsight is relatively easy.

jgrahamc• 12 years ago

The original blog post on Heartbleed said: "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."

In that same blog post we also said that we were revoking and reissuing all our SSL keys, and started the challenge web site to see if private keys could be retrieved.

http://blog.cloudflare.com/answering-the-critical-question-c...

So, yeah, we didn't from the outset figure out how to get the private keys, but we decided that the risk was too high so we want ahead with revocation.

How Heartbleed Leaked Private Keys

Related Stories