Cracking Cloudflare's heartbleed challenge | Hacker News Reader

Cracking Cloudflare's heartbleed challenge

blog.indutny.com

198 pointstomkwok30 comments

This is the code used by the first person to extract the private key.

And as he mentioned, it's a node.js script (plus the node-v0.10.26.patch).

Thank you for the post explaining.

It's great to have good guys like you around. Keep up with the good job.

indutny: your sibling comment is dead because it's the exact same text as your previous comment, and HN code killed it as a double-post. https://news.ycombinator.com/item?id=7576670 <- from 3 days ago lol

Thanks for letting me know. I'll try to be unpredictable.

But, you know, predictably unpredictable.

Just include a UUID at the end of every comment. 0445BD22-4DB2-4238-AB12-38E8766E8FBF

Which one's better: https://github.com/indutny/heartbleed (in node.js) or https://github.com/robertdavidgraham/heartleech (in C)?

I've published another toolset in Python here: https://github.com/einaros/heartbleed-tools

The final test I did before publishing yielded ~100Mbit/sec of bleed from the challenge server, and had the prime in a few secs.

I also detailed a couple of other challenge observations here: https://hacking.ventures/rsa-keys-in-heartbleed-memory/

Thanks for publishing. FWIW I tried your tools, and it said my server Nginx HTTPS was vulnerable, but I couldn't get any keys out of it. I created a 180MB dump file, and then scanned it, and it finished without finding keys (and I repeated this again)

I also tried the code you linked here: https://news.ycombinator.com/item?id=7577659

This also failed, and it actually said my server was likely not vulnerable?

I compiled my own Nginx, (but not my own SSL, that came from Debian 7.0 Wheezy)

Linux ... 3.9.3-x86_64-linode33 #1 SMP Mon May 20 10:22:57 EDT 2013 x86_64 GNU/Linux

OpenSSL 1.0.1e 11 Feb 2013

I just upgraded the Debian libssl1.0.0 package, and now your code says I am safe. I see there is the len(all_data) > 24 check.

Should compiling my own Nginx have any effect on whether the exploit works? I would think not, but 2 different exploits failed (although maybe I didn't run it long enough).

FWIW it was Nginx 1.0.12.

EDIT: FWIW, now that I read Cloudflare's results, they think the Nginx server is only vulnerable shortly after being restarted. My server was running for months, which may have explained why it wasn't vulnerable. Oh well.

http://blog.cloudflare.com/the-results-of-the-cloudflare-cha...

No, the primes (and thus key) can be retrieved at any time, but it may be more frequently found right after reboot.

I would recommend you to gather at least a gigabyte before digging for the key - preferably more. I dumped 43 GB from CloudFlare on Sunday, and found the prime 194 times in that dump. It can be found in much less time, however. Here's a test I just did against the CloudFlare server, resulting in the full prime 34 times in 60 seconds: https://twitter.com/einaros/status/456136820913238016

The code from the second posted you noted (https://news.ycombinator.com/item?id=7577659) isn't mine. That one builds off of the original Python PoC, which fails for a lot of configurations.

The Github code is the first publication I've done. Let me know if you see a server that's vulnerable, that the Github code fails to detect.

On other hand - you could try using my tool, and keep it running up until it'll find the key. It doesn't collect any dumps and does all processing in a real time.

I didn't actually write mine to collect primes :) I'm working with data dumped from other network devices, and for the most running various Yara rules during and after collection.

Was the other prime present in your 43 GB dump or just the one starting with 0xc4ea13ad? Or any other components of the private key?

My own program only saved the snippets of memory in which a little-endian prime was detected - I didn't keep the rest of the data.

Doing realtime prime detection is trivial in mine as well. Either pipe the outfile or add to the lib. I didn't write the dump tool with keys as primary target; they just happened to be there.

Sorry, my comment may have come across as an unnecessary criticism of your technique rather than how I intended it - as mentioning a shortcoming of my program in not saving all data received, and that you may be able to get some interesting results from your dump by searching for other key data and in different formats.

Ah. Well if you want to dig, I've still got the 43 GB from CloudFlare!

I couldn't get heartleech to build at all. The Makefile is malformed, for a start.

Yes, but you don't really need the Makefile. Just check out README.md and do as it says, and it should build just fine. Actually just

$ gcc -o heartleech -lcrypto -lssl -ldl heartleech.c

might work dependening a bit on the distro. Seems to work, too.

It doesn't link for me on Ubuntu 13.10. I wasn't going to be too hard on a quick project for being unportable, but a broken build tool makes it difficult to get working anywhere.

Is it so hard to look at the README?

> This is tricky. This uses the ssl3_write_bytes() function in order to send heartbeats encrypted after the SSL handshake is complete. This function is sometimes exported in OpenSSL libraries, and sometimes not.

> If that's the trouble, then you have to download and build OpenSSL, then link this tool with their object files. I did this by doing:

    git clone git://git.openssl.org/openssl.git
    cd openssl
    ./config
    make depend
    make

    gcc ../heartleech/heartleech.c libcrypto.a libssl.a -ldl -o heartleech

> This is evil, because I'm simultaneously linking to the local libraries and the system libraries for OpenSSL, but it seems to work without too much trouble.

Sorry if I wasn't clear, but I did try that. Result: http://pastebin.com/mM3G7NgX I finally got it working by using instructions from a different heartbleed PoC:

  gcc heartleech.c -o heartleech -lssl -lcrypto -ldl -I~/openssl-1.0.1g/include -L~/openssl-1.0.1g

Gotcha. Sorry to be snippy earlier!

Maybe the reported byte length was incorrect.

That is because the tab on line 4 was converted to 4 spaces. A simple find + replace fixes the problem.

Sure, if you can interpret "Makefile:4: * * * missing separator. Stop."

To be fair, if you have hand-created many Makefiles, you'd already be quite familiar with that error.

I think it is a matter of taste mostly, they all use similar method, I think

An interesting variant of prime-number search. It may not turn up the largest primes yet known... just the economically valuable smaller ones.

Nice. To speed things up, you could look for 128 byte malloc'ed chunks with a 16 byte header of "xx xx xx xx 90 00 00 00" or "xx xx xx xx 91 00 00 00" (for a 2048 bit modulus).

Looks to me like OpenSSL caches the modulus for Montgomery multiplication and that's where the primes in higher memory are coming from (see rsa_eay.c around line 774).

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