Kirill Shipulin is a security engineer at Positive Technologies, a company where he studies malware, network attacks and exploitation techniques to build a strong intrusion detection system and keep it up to modern threats. During his time at Positive Technologies he analysed hundreds of found security vulnerabilities and malware attacks producing IDS detection rules for the majority of famous open source and proprietary products.

Turning IDS signatures against an IDS itself: a new evasion technique

When we speak about an IDS, we can hardly imagine that its heart, network signatures, may be dangerous. An arms race between attackers and IDS carries on. In the past, detection bypass was possible due to inspection bugs in transport layer protocols. Now almost all popular methods of bypassing IDS rely on defects and errors of higher-level network layer protocol parsers, as well as their lack of universality. A bug in the Suricata operation logic and the scale of its possible consequences give us another insight into bypass of IDS, and allow attackers use inspection signatures in their own interests. From now on, IDS signatures not only belong to defense systems, but also serve as attackers’ tools. In my report I’ll tell you how to turn available signatures against the system to paralyze its operation, as well as deliberate on how compromises between performance and security, speed and quality can produce other breaches for bypass.