OpenSSL heartbleed CVE-2014-0160 – Data leaks make my heart bleed

The heartbleed bug was introduced in OpenSSL 1.0.1 and is present in

  • 1.0.1
  • 1.0.1a
  • 1.0.1b
  • 1.0.1c
  • 1.0.1d
  • 1.0.1e
  • 1.0.1f

The bug is not present in 1.0.1g, nor is it present in the 1.0.0 branch nor the 0.9.8 branch of OpenSSL some sources report 1.0.2-beta is also affected by this bug at the time of writing, however it is a beta product and I would really recommend not to use beta quality releases for something as fundamentally important as OpenSSL in production.

The bug itself is within the heartbeat extension of OpenSSL (RFC6520). The bug allows an attacker to leak the memory in up to 64k chunks, this is not to say the data being leaked is limited to 64k as the attacker can continually abuse this bug to leak data, until they are satisfied with what has been recovered.

At worst the attacker can retrieve the private keys, the implications for which is that the attacker now has the keys to decrypt the encrypted data, as such the only way to be 100% certain of protection against this bug is to first update OpenSSL (>= 1.0.1g) and then revoke and regenerate new keys and certificates, expect to see a tirade of revocations and re-issuing of CA certs and the like in the coming days.

So how does this affect you as a MySQL user?

Taking Percona Server as an example, this is linked against OpenSSL, meaning if you want to use TLS for your client connections and/or your replication connections you’re going to need to have openSSL installed.

You can find your version easily via your package manager for example:

  • rpm -q openssl
  • dpkg-query -W openssl

If you’re running a vulnerable installation of OpenSSL an update will be required.

  • update OpenSSL >= 1.0.1g
  1. 1.0.1e-2+deb7u5 is reported as patched on debian,
  2. 1.0.1e-16.el6_5.7 is reported as patched in RedHat and CentOS
  3. 1.0.1e-37.66 changelogs note this has been patched on Amazon AMI
  • shutdown mysqld
  • regenerate keys and certs used by mysql for TLS connections (revoking the old certs if possible to do so)
  • start mysqld

You can read more about the heartbleed bug at heartbleed.com Redhat Bugzilla Mitre CVE filing Ubuntu Security Notice

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Heartbleed: Separating FAQ From FUD

If you’ve been following this blog (my colleague, David Busby, posted about it yesterday) or any tech news outlet in the past few days, you’ve probably seen some mention of the “Heartbleed” vulnerability in certain versions of the OpenSSL library.

So what is ‘Heartbleed’, really?

In short, Heartbleed is an information-leak issue. An attacker can exploit this bug to retrieve the contents of a server’s memory without any need for local access. According to the researchers that discovered it, this can be done without leaving any trace of compromise on the system. In other words, if you’re vulnerable, they can steal your keys and you won’t even notice that they’ve gone missing. I use the word “keys” literally here; by being able to access the contents of the impacted service’s memory, the attacker is able to retrieve, among other things, private encryption keys for SSL/TLS-based services, which means that the attacker would be able to decrypt the communications, impersonate other users (see here, for example, for a session hijacking attack based on this bug), and generally gain access to data which is otherwise believed to be secure. This is a big deal. It isn’t often that bugs have their own dedicated websites and domain names, but this one does: http://www.heartbleed.com

Why is it such a big deal?

One, because it has apparently been in existence since at least 2012. Two, because SSL encryption is widespread across the Internet. And three, because there’s no way to know if your keys have been compromised. The best detection that currently exists for this are some Snort rules, but if you’re not using Snort or some other IDS, then you’re basically in the dark.

What kinds of services are impacted?

Any software that uses the SSL/TLS features of a vulnerable version of OpenSSL. This means Apache, NGINX, Percona Server, MariaDB, the commercial version of MySQL 5.6.6+, Dovecot, Postfix, SSL/TLS VPN software (OpenVPN, for example), instant-messaging clients, and many more. Also, software packages that bundle their own vulnerable version of SSL rather than relying on the system’s version, which might be patched. In other words, it’s probably easier to explain what isn’t affected.

What’s NOT impacted?

SSH does not use SSL/TLS, so you’re OK there. If you downloaded a binary installation of MySQL community from Oracle, you’re also OK, because the community builds use yaSSL, which is not known to be vulnerable to this bug. Obviously, any service which doesn’t use SSL/TLS is not going to be vulnerable, either, since the salient code paths aren’t going to be executed. So, for example, if you don’t use SSL for your MySQL connections, then this bug isn’t going to affect your database server, although it probably still impacts you in other ways (e.g., your web servers).

What about Amazon cloud services?

According to Amazon’s security bulletin on the issue, all vulnerable services have been patched, but they still recommend that you rotate your SSL certificates.

Do I need to upgrade Percona Server, MySQL, NGINX, Apache, or other server software?

No, not unless you built any of these and statically-linked them with a vulnerable version of OpenSSL. This is not common. 99% of affected users can fix this issue by upgrading their OpenSSL libraries and cycling their keys/certificates.

What about client-level tools, like Percona Toolkit or XtraBackup?

Again, no. The client sides of Percona Toolkit, Percona XtraBackup, and Percona Cloud Tools (PCT) are not impacted. Moreover, the PCT website has already been patched. Encrypted backups are still secure.

There are some conflicting reports out there about exactly how much information leakage this bug allows. What’s the deal?

Some of the news articles and blogs claim that with this bug, any piece of the server’s memory can be accessed. Others have stated that the disclosure is limited to memory space owned by processes using a vulnerable version of OpenSSL. As far as we are aware, and as reported in CERT’s Vulnerability Notes Database, the impact of the bug is the latter; i.e., it is NOT possible for an attacker to use this exploit to retrieve arbitrary bits of your server’s memory, only bits of memory from your vulnerable services. That said, your vulnerable services could still leak information that attackers could exploit in other ways.

How do I know if I’m affected?

You can test your web server at http://filippo.io/Heartbleed/ – enter your site’s URL and see what it says. If you have Go installed, you can also get a command-line tool from Github and test from the privacy of your own workstation. There’s also a Python implementation. You can also check the version of OpenSSL that’s installed on your servers. If you’re running OpenSSL 1.0.1 through 1.0.1f or 1.0.2-beta, you’re vulnerable. (Side note here: some distributions, such as RHEL/CentOS, have patched the issue without actually updating the OpenSSL version number; on RPM-based systems you can view the changelog to see if it’s been fixed, for example:

rpm -q --changelog openssl | head -2
* Mon Apr 07 2014 Tomáš Mráz <tmraz@redhat.com> 1.0.1e-16.7
- fix CVE-2014-0160 - information disclosure in TLS heartbeat extension

Also, note that versions of OpenSSL prior to 1.0.1 are not known to be vulnerable. If you’re still unsure, we would be happy to assist you in determining the extent of the issue in your environment and taking any required corrective action. Just give us a call.

How can I know if I’ve been compromised?

If you’ve already been compromised, you won’t. However, if you use Snort as an IDS, you can use some rules developed by Fox-IT to detect and defer new attacks; other IDS/IPS vendors may have similar rule updates available. Without some sort of IDS in place, however, attacks can and will go unnoticed.

Are there any exploits for this currently out there?

Currently, yes, there are some proofs-of-concept floating around out there, although before this week, that was uncertain. But given that this is likely a 2-year-old bug, I would be quite surprised if someone, somewhere (you came to my talk at Percona Live last week, didn’t you? Remember what I said about assuming that you’re already owned?) didn’t have a solid, viable exploit.

So, then, what should I do?

Ubuntu, RedHat/CentOS, Amazon, and Fedora have already released patched versions of the OpenSSL library. Upgrade now. Do it now, as in right now. If you’ve compiled your own version of OpenSSL from source, upgrade to 1.0.1g or rebuild your existing source with the -DOPENSSL_NO_HEARTBEATS flag.

Once that’s been done, stop any certificate-using services, regenerate the private keys for any services that use SSL (Apache, MySQL, whatever), and then obtain a new SSL certificate from whatever certificate authority you’re using. Once the new certificates are installed, restart your services. You can also, of course, do the private key regeneration and certificate cycling on a separate machine, and only bring the service down long enough to install the new keys and certificates. Yes, you will need to restart MySQL. Or Apache. Or whatever. Full stop, full start, no SIGHUP (or equivalent).

Unfortunately, that’s still not all. Keeping in mind the nature of this bug, you should also change / reset any user passwords and/or user sessions that were in effect prior to patching your system and recycling your keys. See, for example, the session hijacking exploit referenced above. Also note that Google services were, prior to their patching of the bug, vulnerable to this issue, which means that it’s entirely possible that your Gmail login (or any other Google-related login) could have been compromised.

Can I get away with just upgrading OpenSSL?

NO. At a bare minimum, you will need to restart your services, but in order to really be sure you’ve fixed the problem, you also need to cycle your keys and certificates (and revoke your old ones, if possible). This is the time-consuming part, but since you have no way of knowing whether or not someone has previously compromised your private keys (and you can bet that now that the bug is public, there will be a lot of would-be miscreants out there looking for servers to abuse), the only safe thing to do is cycle them. You wouldn’t leave your locks unchanged after being burgled, would you?

Also note that once you do upgrade OpenSSL, you can get a quick list of the services that need to be restarted by running the following:

sudo lsof | grep ssl | grep DEL

Where can I get help and/or more information?

In addition to the assorted links already mentioned, you can read up on the nuts and bolts of this bug, or various news articles such as this or this. There are a lot of articles out there right now, most of which are characterizing this as a major issue. It is. Test your vulnerability, upgrade your OpenSSL and rotate your private keys and certificates, and then change your passwords.

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