Snort Signature for Heartbleed Low FOX IT http://blog.fox-it.com/2014/04/08/openssl-heartbleed-bug-live-blog/ any any (msg:"FOX-SRT - Flowbit - TLS-SSL Client Hello"; flow:established; dsize:< 500; content:"|16 03|"; depth:2; byte_test:1, <=, 2, 3; byte_test:1, !=, 2, 1; content:"|01|"; offset:5; depth:1; content:"|03|"; offset:9; byte_test:1, <=, 3, 10; byte_test:1, !=, 2, 9; content:"|00 0f 00|"; flowbits:set,foxsslsession; flowbits:noalert; threshold:type limit, track by_src, count 1, seconds 60; reference:cve,2014-0160; classtype:bad-unknown; sid: 21001130; rev:9;)]]> any any (msg:"FOX-SRT - Suspicious - TLS-SSL Large Heartbeat Response"; flow:established; flowbits:isset,foxsslsession; content:"|18 03|"; depth: 2; byte_test:1, <=, 3, 2; byte_test:1, !=, 2, 1; byte_test:2, >, 200, 3; threshold:type limit, track by_src, count 1, seconds 600; reference:cve,2014-0160; classtype:bad-unknown; sid: 21001131; rev:5;)]]> High Generic Heartbleed Exploits Heartbleed CVE-2013-3893