Check out the new USENIX Web site.
USENIX, The Advanced Computing Systems Association

15th USENIX Security Symposium Abstract

Pp. 225–240 of the Proceedings

SigFree: A Signature-free Buffer Overflow Attack Blocker

Xinran Wang, Chi-Chun Pan, Peng Liu, and Sencun Zhu, The Pennsylvania State University


We propose SigFree, a realtime, signature-free, out-of-the-box, application layer blocker for preventing buffer overflow attacks, one of the most serious cyber security threats. SigFree can filter out code-injection buffer overflow attack messages targeting at various Internet services such as web service. Motivated by the observation that buffer overflow attacks typically contain executables whereas legitimate client requests never contain executables in most Internet services, SigFree blocks attacks by detecting the presence of code. SigFree first blindly dissembles and extracts instruction sequences from a request. It then applies a novel technique called code abstraction, which uses data flow anomaly to prune useless instructions in an instruction sequence. Finally it compares the number of useful instructions to a threshold to determine if this instruction sequence contains code. SigFree is signature free, thus it can block new and unknown buffer overflow attacks; SigFree is also immunized from most attack-side code obfuscation methods. Since SigFree is transparent to the servers being protected, it is good for economical Internet wide deployment with very low deployment and maintenance cost. We implemented and tested SigFree; our experimental study showed that SigFree could block all types of codeinjection attack packets (above 250) tested in our experiments. Moreover, SigFree causes negligible throughput degradation to normal client requests.
  • View the full text of this paper in HTML and PDF. Listen to the presentation and Q & A in MP3 format.
    Click here if you have forgotten your password Until August 2007, you will need your USENIX membership identification in order to access the full papers. The Proceedings are published as a collective work, © 2006 by the USENIX Association. All Rights Reserved. Rights to individual papers remain with the author or the author's employer. Permission is granted for the noncommercial reproduction of the complete work for educational or research purposes. USENIX acknowledges all trademarks within this paper.
To become a USENIX member, please see our Membership Information.

Last changed: 20 Sept. 2006 ch