Level 61
Researchers Jeffrey Walton of Software Integrity and Brooke Stephens of University of Maryland, Baltimore County, have demonstrated how unprivileged user mode code can usually block the proper function of Windows security suites by interfering with their use of Windows synchronization objects.

Multitasking operating systems contain mechanisms for programs to communicate with each other in order to exchange data or control access to resources, such as a port or file or even a process. In UNIX this is accomplished through signals; in Windows there are a series of synchronization facilities for a variety of circumstances.
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