via Dan Goodin, Ars Technica
In the HBO hit series The Wire, disposable cell phones were the bane of detectives' lives. Drug dealers obtained these prepaid "burners" in mass quantities with cash at multiple stores hundreds of miles away from where they were used.
After a week or two of use, a crook would destroy one cheap handset and fetch a new one. The Baltimore Police detectives' inability to tap the phones stymied their investigation into one of the city's most ruthless crime families — until they found a way to track the devices.
The National Security Agency may have made a similar breakthrough. Cato Institute researcher Julian Sanchez recently pulled a few sentences from a 2009 declaration by NSA Director Keith Alexander. They describe an unnamed tool that routinely accessed the vast database of call records assembled by the NSA. Sanchez argues that the purpose may be to identify burner phones used by NSA targets. (more) (via Schneier)