updated 06:20 pm EDT, Sun March 25, 2012
T-Mobile USA Web Guard seen overreaching
An optional web censoring filter used by T-Mobile's US division, Web Guard has been found stretching too far in a new study by the Open Observatory of Network Interference. As implemented so far, it not only blocks the intended 'adult' sites but a number of clean sites, such as Cosmopolitan magazine, the Internet Archive, French TV guide Programme, and many others that have no reason to be blocked. In a degree of irony, it blocks the page for the censorship circumvention of the Tor Project, religious site Kath, and a redirect page that results from Italy's own national filter.
Web Guard is also ineffective against secure data, OONI founds. As it's using a proxy to inspect web (HTTP) packets against a blacklist of sites, it falls apart when someone uses HTTPS or another form of encrypted traffic. The error page when a user runs into the block also isn't clear as to how to turn the filter off, although this might be intentional to prevent teens and children from easily defeating the censor.
As an optional program, only some users will ever encounter the accidental censorship. The real-world problems still underscore the dangers of mandating censorship, particularly on mobile sites. Similar blocks have been proposed by media studios to guard piracy, but have been denied in the EU over both a right to exchange data and the risks of false positives. [via Boing Boing]