Posts Tagged ‘openssl’

Bleeding Heart Security

Friday, April 11th, 2014

Unless you’ve been living under a rock the past few days, you’ve probably heard about the Heartbleed vulnerability in OpenSSL that was disclosed on Monday, April 7th. Systems and network administrators across the globe have spent the last few days testing for this vulnerability, patching systems, and probably rocking in the corner while crying. Yes, it’s that bad. What’s more, there are a number of reports that intelligence agencies may have known about this vulnerability for some time now.

The quick and dirty is that a buffer overflow bug in the code allows an attacker to remotely read memory of an affected system in 64k chunks. The only memory accessible to an attacker would be memory used by the process being connected to, but, depending on the process, there may be a LOT of useful data in there. For instance, Yahoo was leaking usernames and passwords until late Tuesday evening.

The fabulous web comic, xkcd, explains how the attack works in layman’s terms. If you’re interested in the real nitty gritty of this vulnerability, though, there’s an excellent write-up on the IOActive Labs blog. If you’re the type that likes to play, you can find proof-of-concept code here. And let’s not forget about the client side, there’s PoC code for that as well.

OpenSSL versions 1.0.1 through 1.0.1f as well as the 1.0.2 beta code are affected. The folks at OpenSSL released version 1.0.1g on Monday which fixed the problem. Or, at least, the current problem. There’s a bit of chatter about other issues that may be lurking in the OpenSSL codebase.

Now that a few days have passed, however, what remains to be done? After all, everyone has patched their servers, right? Merely patching doesn’t make the problem disappear, though. Vulnerable code is out there and mistakes can be made. For the foreseeable future, you should be regularly scanning your network for vulnerable systems with something like Nmap. The Nmap NSE for Heartbleed scanning is already available. Alternatively, you can use something like Nagios to regularly check your existing servers.

Patching immediately may not have prevented a breach, either. Since Heartbleed doesn’t leave much of a trace beyond some oddities that your IDS may have seen, there’s virtually no way to know if anything has been taken. The best way to deal with this is to just go ahead and assume that your private keys are compromised and start replacing them. New keys, new certs. It’s painful, it’s slow, but it’s necessary.

For end users, the best thing you can do is change your passwords. I’m not aware of any “big” websites that have not patched by now, so changing passwords should be relatively safe. However, that said, Wired and Engadget have some of the best advice I’ve seen about this. In short, change your passwords today, then change them again in a few weeks. If you’re really paranoid, change them a third time in about a month. By that time, any site that is going to patch will have already patched.

Unfortunately, I think the fun is just beginning. I expect we’ll start seeing a number of related attacks. Phishing attacks are the most likely in the beginning. If private keys were compromised, then attackers can potentially impersonate websites, including their SSL certificates. This would likely involve a DNS poisoning attack, but could also be accomplished by compromising a user’s local system and setting a hosts file entry. Certificate revocation is a potential defense against this, but since many browsers have CRL checks disabled by default, it probably won’t help. Users will have to watch what they click, where they go, and what software they run. Not much different from the advice given already.

Another possible source of threats are consumer devices. As Bruce Schneier put it, “An upgrade path that involves the trash, a visit to Best Buy, and a credit card isn’t going to be fun for anyone.” What he’s referring to are the many embedded devices we use on a daily basis that may never receive updates to protect the end user. In other words, that router you purchased from the discount store? That may be affected and unless you replace it, you’ll continue to be vulnerable. Fortunately, most of these devices aren’t configured, by default, to face the Internet, so there may yet be hope.

The Heartbleed vulnerability is a serious contender for the worst security vulnerability ever released. I’m not sure of another vulnerability that exposes so many systems to such a degree as this one. Network and systems administrators will be cleaning up after this one for a while.