From a Google search of NetSweeper filtering categories...
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1.2.4. Criminal Skills
Criminal Skills includes instructions or methods that promote, encourage, or provide the skills to do anything that is generally considered to be illegal, criminal, harmful to the general public, and/or that are forbidden by laws. This category does not necessarily reflect the laws of any particular region or country. This category includes sites that promote academic cheating or software hacking/key breaking. It typically excludes any site that deals with the prevention of criminal activity.
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I occasionally see posts here about cracking iPhone etc. So maybe that's where the categorization came from?
Cheers.