Summary

A lot of complexity is introduced when a program can share resources among concurrent threads or processes. Serious issues can occur when an application fails to handle concurrent access to shared resources. This failure can result in execution entities interfering with each other and ultimately corrupting the program to the point of a successful compromiseeither by exploitation for elevated privileges or bringing the program to a grinding halt.

You've examined problems in dealing with multiple execution instances simultaneously operating on shared resources, including issues with process and thread synchronization, and signal handling in UNIX environments. Identifying these issues can be extremely difficult and requires detailed analysis of the application's concurrent programming elements. However, you should now be familiar with the techniques necessary to perform a thorough and effective assessment of vulnerabilities that occur due to synchronization issues.