Binary rewriting techniques have been developed to allow users to enforce security policies directly on mobile code. However, the performance overheads incurred for improved security, particularly in large organizations with many end-hosts, accentuate the inherent challenges of code rewriting and limit the rate of improvement in these systems.

We integrate a binary code rewriter with a web caching proxy and build the security system called PBJARS, a Proxy-based JAva Rewriting System. PBJARS compliments existing JVM security mechanisms by placing another line of security defense in the code path code associated with code downloads. It gives system administrators centralized security control at the level of administrative domains at proxy servers. We evaluated PB-JARS using real Java binary traffic models derived from analyzing real web trace records. Our experimental results show that the overhead added by binary rewriting can be significantly amortized by web caching and PB-JARS adds negligible performance impact on proxy servers.