Note: this page is now rather old, but I'll leave it up for historical purposes. It was originally written in March 2000.
Given that Mattel now own the rights to Eddy Jansson and Matthew Skala's `The Breaking of CyberPatrol® 4' document, I've now taken it down. Sorry, but it now seems like the right thing to do.
Alternatively, if you don't know what this is all about, I suggest you read on: CyberPatrol® is a product produced by Microsystems Software, a subsidiary of Mattel, which claims to block access `inappropriate' Web sites.
This, if well implemented, is (probably) a good thing: personally, I can't see a problem with parents having the means to stop their children seeing pornography and the like.
The objection to CyberPatrol® basically stems from the fact that it is not done well: it blocks sites only via URL or IP address, which is never going to be good enough to catch a lot of sites. Secondly, they don't let you see the list of sites they're blocking. Thirdly, and probably most importantly, they lie about what they block sites on: for example, Peacefire, an anti-censorship organisation, is blocked by CyberPatrol®. CyberPatrol® apparently provides various categories, for example `Partial Nudity' or `Illegal Gambling', which an administrator can choose to block access to. However, Peacefire is blocked under all of CyberPatrol®'s categories, despite having nothing to do with them. All it did was to say that CyberPatrol® wasn't actually as good as it was claiming to be.
This kind of information was revealed when the above mentioned Eddy Jansson and Matthew Skala reversed engineered the (very trivially) encrypted list of blocked sites used by CyberPatrol®, and placed this information on their Web sites. Mattel then sued them, claiming all sorts of copyright infringements and the like. This was eventually settled out of court, with Mattel acquiring the rights to both the essay and the programs.