Thursday, April 10, 2014

Heartbleed Continued - OpenSSL Client Memory Exposed

The Heartbleed vulnerability is bad. Not only does it pose a risk to servers running the vulnerable version of OpenSSL (1.0.1 through 1.0.1f) with heartbeats enabled, it also poses a serious risk to clients running the vulnerable versions.

OpenSSL clients process heartbeats using the same vulnerable functions: tls1_process_heartbeat() and dtls1_process_heartbeat(). The same memcpy() overread detailed in our previous blog post allows malicious servers to read blocks of client memory. In internal testing we were able to extract memory from several client programs such as curl and wget, that link against the vulnerable OpenSSL versions.  It is important to note the versions of these programs does not necessarily matter, if they are linking against the vulnerable OpenSSL versions.

Research into other clients that link against the vulnerable versions of OpenSSL continues. Again, it is strongly recommended that you upgrade to OpenSSL version 1.0.1g or install a version of OpenSSL with heartbeats disabled.

We have released detection for the client side attack in SIDs 30520 through 30523, we have expanded detection port ranges to cover more vulnerable clients and servers, and last but not least, all Heartbleed rules have been added to the community ruleset - because we care.
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