A “Please, Don’t Waste my Time” Approach and the Sourcefire/Snort Evasion

This is a guest post from Antonios Atlasis.

Yesterday we (Rafael Schaefer, Enno and me) had the pleasure to deliver together our talk at BlackHat Europe 2014 named Evasion of High-End IDPS Devices at the IPv6 Era (by the way, latest slides can be found here and the white paper here). In this talk we summarised all the IDPS evasion techniques that we have found so far. At previous blogposts I had the chance to describe how to evade Suricata and TippingPoint. In this post I am going to describe some other techniques that can be used to evade Snort, and its companion commercial version, Sourcefire. The tool used to evade these IDPS is –  what else – Chiron.

The versions that we used for our tests are the latest available ones at the time of this writing, that is:

  • Sourcefire, Model 3D7020 (63) Version (Build 48), VDB version 216.
  • Snort GRE (build 77), Registered User’s Release Rules.

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