Preventing format-string attacks via automatic and efficient dynamic checking

ABSTRACT

We propose preventing format-string attacks with a combination of static dataflow analysis and dynamic white-lists of safe address ranges. The dynamic nature of our white-lists provides the flexibility necessary to encode a very precise security policy---namely, that %n -specifiers in printf-style functions should modify a memory location x only if the programmer explicitly passes a pointer to x. Our static dataflow analysis and source transformations let us automatically maintain and check the white-list without any programmer effort---they merely need to change the Makefile. Our analysis also detects pointers passed to vprintf-style functions through (possibly multiple layers of) wrapper functions. Our results establish that our approach provides better protection than previous work and incurs little performance overhead.

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INDEX TERMS

Primary Classification:
  D. Software
  D.4 OPERATING SYSTEMS
      D.4.6 Security and Protection
          Subjects: Invasive software (e.g., viruses, worms, Trojan horses)

Additional Classification:
  D. Software
  D.2 SOFTWARE ENGINEERING
      D.2.0 General
          Subjects: Protection mechanisms
      D.2.4 Software/Program Verification
          Subjects: Reliability

General Terms:
Security

Keywords:
dynamic checking, format-string attacks, static analysis, white-lists