Packed, Printable, and Polymorphic Return-Oriented Programming

Return-oriented programming (ROP) is an attack that has been shown to be able to circumvent W ⊕X protection. However, it was not clear if ROP can be made as powerful as non-ROP malicious code in other aspects, e.g., be packed to make static analysis difficult, be printable to evade non-ASCII filtering, be polymorphic to evade signaturebased detection, etc. Research in these potential advances in ROP is important in designing counter-measures. In this paper, we show that ROP code could be packed, printable, and polymorphic. We demonstrate this by proposing a packer that produces printable and polymorphic ROP code. It works on virtually any unpacked ROP code and produces packed code that is self-contained. We implement our packer and demonstrate that it works on both Windows XP and Windows 7 platforms. keywords: Return-oriented programming, packer, printable shellcode, polymorphic malware