PMASCE-Polymorphic and Metamorphic Shellcode Creation Engine

Abstract

Signature detection is ultimately going to be of no use in the future of AVs and IDS systems. The obfuscation of several parts of the exploit code is becoming so detailed that it could become almost impossible to uncover the various layers of obfuscation and reveal the actual malicious payload. In addition to obfuscation, there are sandbox evasion techniques being followed by attackers to hide from IDS if they try to study their behaviour in a simulated environment. Also, a worm may not attack in one go but in multiple stages, probably sending a small, innocent looking code first, which prepares the system for advance attacks. The worm may become polymorphic or metamorphic depending upon the attack complexity required. Polymorphic blending enables a worm to merge with normal traffic so well that anomaly-based IDS’ are unable to discern it from normal packets. To top it all, attackers are now able to create a M:N worm which means that a worm can have many signatures, many behaviours. This is done by changing the runtime behaviour of the shellcode. In this paper we propose an engine called PMASCE-Polymorphic and Metamorphic Shellcode Creation Engine. This engine enumerates all the steps which are required to be followed to create a strong polymorphic or metamorphic shellcode. This type of shellcode is created taking into account all the defence mechanisms carried out by the detection systems currently. Once all these steps are analysed, we aim to advance the research in IDS so that the existing IDS’ can be hardened to detect all malwarespolymorphic or metamorphic, employing all kinds of techniques of the present and the future.