Revisiting the myth of Cisco IOS diversity: recent advances in reliable shellcode design

IOS firmware diversity, the unintended consequence of a complex firmware compilation process, has historically made reliable exploitation of Cisco routers difficult. With approximately 300,000 unique IOS images in existence, a new class of version‐agnostic shellcode is needed in order to make the large‐scale exploitation of Cisco IOS possible. The purpose of this paper is to show that such attacks are now feasible by demonstrating two different reliable shellcodes that will operate correctly over many Cisco hardware platforms and all known IOS versions.

The paper examines prior work in the area of Cisco IOS rootkits and constructs a novel IOS version‐agnostic rootkit called the interrupt‐hijack rootkit.

As the experimental results show, the techniques proposed in this paper can reliably inject command and control capabilities into arbitrary IOS images in a version‐agnostic manner.

The authors believe that the technique presented in this paper overcomes an important hurdle in the large‐scale, reliable rootkit execution within Cisco IOS. Thus, effective host‐based defence for such routers is imperative for maintaining the integrity of our global communication infrastructures.