Parameters of a programs runtime environment such as the machine architecture and operating system largely determine whether a vulnerability can be exploited. For example, the machine word size is an important factor in an integer overflow attack and likewise the memory layout of a process in a buffer or heap overflow attack. In this paper, we present an analysis of the effects of a runtime environment on a languages data types. Based on this analysis, we have developed Archerr, an automated one-pass source-to-source transformer that derives appropriate itecture dependent runtime safety or checks and inserts them in C source programs. Our approach achieves comprehensive vulnerability coverage against a wide array of program-level exploits including integer overflows/underflows. We demonstrate the efficacy of our technique on versions of C programs with known vulnerabilities such as Sendmail. We have benchmarked our technique and the results show that it is in general less expensive than other well-known runtime techniques, and at the same time requires no extensions to the C programming language. Additional benefits include the ability to gracefully handle arbitrary pointer usage, aliasing, and typecasting.
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