The address book in question was stored on Hilton's Side Kick II smart phone, and backed up on a T-Mobile server.
Kevin Kissell, an architect at MIPS Technologies Inc., said he wondered "whether the hackers accessed numbers stored in the phone a default for most mobiles or on the SIM card." He also wondered "whether the outcome might have been different if Ms. Hilton had stored her numbers on the SIM."
T-Mobile wouldn't discuss its investigation. A company spokesman, however, suggested that "someone had access to one of Ms. Hilton's devices and/or knew her account password."
Most reports postulated an attack on T-Mobile's server rather than the client. Speculation was based on the fact that T-Mobile's database was hacked last year by 22-year-old Nicols Jacobsen, who pleaded guilty earlier this month.
Nonetheless, speculation was rampant regarding how hackers might have snagged her account password.
Possible scenarios ranged from correctly guessing the name Hilton's dog to the theft of records and passwords stored in her SideKick II. The phone's Bluetooth interface was also cited.
Hackers could have accessed T-Mobile's database using SQL (structured query language) injections, said David Naccache, vice president, research and innovation at Gemplus, based here. By adding SQL to a query, Naccache said it's possible to manipulate a database in ways not anticipated by administrators.
Or, Hilton could have handed her phone to an acquaintance who extracted the information, said Naccache. "You need a key to the door in order to get into a house," he said. "But you can also get into the house through a window." Naccache, a forensic expert, said a hack was possible anywhere between the handset and the network.
Even if the server was hacked rather than the client, Kissell's questions remain valid for chip vendors, SIM card manufacturers and mobile handset companies. All are racing to add security features to next-generation phone and network designs.
Added Mike Yonker, director of Technology Strategy at Texas Instruments Inc., "This incident really stresses the need for stronger security. Consumers have reason to question even the security of the servers where their data is stored at the mobile operator."