1 / 8

Example of Anomaly Detection

Example of Anomaly Detection. Sequence of system calls (Forrest 1996) Training Training data: open read write open mmap write fchmod close Sliding window of size 1+3 (1 followed by 3) open read write open open mmap write fchmod read write open mmap write open mmap write

watsonhelen
Download Presentation

Example of Anomaly Detection

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Example of Anomaly Detection • Sequence of system calls (Forrest 1996) • Training • Training data: open read write open mmap write fchmod close • Sliding window of size 1+3 (1 followed by 3) open read write open open mmap write fchmod read write open mmap write open mmap write write fchmod close mmap write fchmod close fchmod close close • This is the normal behavior

  2. Example of Anomaly Detection • Detection open read write open open mmap write fchmod read write open mmap write open mmap write write fchmod close mmap write fchmod close fchmod close close • open read readopen mmap write fchmod close • Differs in 5 places: • Second read should be write (1st line) • Second read should be write (3rd line) • Second open should be write (3rd line) • mmap should be open (3rd line) • write should be mmap (3rd line) • 18 possible places of difference • 18=5*3+2+1 • Mismatch rate 5/18  28% ? A pre-defined threshold

  3. Stack Frame c o d e r e t a d d r r e t a d d r 3 GB w/o Randomization b u f Exploit!

  4. Stack Frame c o d e r e t a d d r r e t a d d r 3 GB w/ Randomization b u f b u f crash

  5. Stack Frame c o d e r e t a d d r r e t a d d r De-Randomization 1 Pad b u f crash Step 1

  6. Stack Frame c o d e r e t a d d r r e t a d d r De-Randomization 2 Pad b u f crash Step 2

  7. Stack Frame c o d e r e t a d d r r e t a d d r De-Randomization 3 Pad b u f Exploit! 216 seconds (avg.) to de-randomize! Step 3 http://www.stanford.edu/~blp/papers/asrandom.pdf

  8. c o d e Spraying Attacks • Exploit a buggy application and “spray” attack code in write-able user-level memory areas b u f Exploit!

More Related