By Brian Krebs
washingtonpost.com Staff Writer
Thursday, August 11, 2005 6:38 PM
Verizon Wireless said today that computer programming flaws in its online billing system could have allowed customers to view account information belonging to other customers, possibly exposing limited personal information about millions of people.
A spokesman for the Bedminster, N.J., company, a joint venture between Verizon Communications Corp. and Vodafone Group PLC, declined to say how many of the company's 45 million subscriber accounts were at risk. Verizon Wireless said the problem appeared to be limited to accounts for customers in the eastern United States who had signed up for its "My Account" feature.
The phone giant said it had corrected the glitch as of 2 a.m. Eastern Time today. The "My Account" feature has been available on the Verizon Wireless Web site for the past five years, though spokesman Tom Pica said the company does not yet know how long the faulty code was in place on the service.
Pica confirmed the Web site flaw allowed a user to view another subscriber's balance of remaining airtime minutes and the number of minutes that customer had used in the current billing cycle. Two other flaws could have exposed data about a customer's general location -- i.e., city and state -- and the make and model of phone the customer uses, Pica said.
There is no indication that anyone took advantage of the flaws or that any customer financial information such as Social Security or credit card account numbers was disclosed, Pica said. The flaws also did not allow access to phone numbers associated with customers' incoming and outgoing calls, and "no customer data could be manipulated and changed in any way," he said.
Pica said the company was still assessing whether it would notify customers about the situation, but he said that based on the information gathered so far Verizon Wireless does not believe any sensitive personal information was revealed.
The flaw that exposed account information was reported to Verizon Wireless by Jonathan Zdziarski, a software developer from Milledgeville, Ga., who said he discovered it while writing a computer program that would automatically query his account online and report the number of minutes he had used from his wireless plan.
Zdziarski found that by simply entering another subscriber's wireless phone number on a particular portion of the site, he could pull up some information about that person's account.
Pica said the flaws did not expose customer account balances or latest payment information. But Zdziarski provided washingtonpost.com with a screenshot showing that the vulnerabilities exposed account balances and the date of the most recent payment, a claim that Pica said the company could not confirm.
After Zdziarski's alert, Verizon Wireless technicians reviewed other portions of the company's billing system and fixed one, but the technicians disabled the feature that allowed viewing of customer location until technicians could figure out a way to secure it, according to Pica.
Zdziarski said he later conducted other tests and found that the glitch he discovered could also be exploited to transfer one customer's account to another handset, a technique known as "cloning."
The user of a cloned phone can intercept all of the victim's incoming wireless calls, and also make calls that later would be billed to the victim's account. Zdziarski said he was prevented from fully testing whether the flaw could be used to clone Verizon Wireless phones because the service that allows customers to map existing phone numbers to new handsets appeared to be offline at the time he reported the flaw.
"This was a very easy hack to do," Zdziarski said. "I'm sure if I've discovered it, then certainly your typical 'script kiddie' could figure it out."
Pica said company technicians were still trying to verify Zdziarski's phone-cloning claims.
The incident is just the latest in a string of disclosures from companies that failed to adequately secure access to their customers' personal information. One of Verizon Wireless's biggest competitors, Bellevue, Wash.-based T-Mobile International, disclosed last year that a security hole in its Web site exposed data on at least 400 customers, including a then-active Secret Service agent. Earlier this year, a group of hackers used other flaws in T-Mobile's site to break into the phones of dozens of celebrities, in an incident that exposed racy photographs and personal notes and contacts for hotel heiress and socialite Paris Hilton.
Bruce Schneier, founder of Counterpane Internet Security in Mountain View, Calif., said the type of security vulnerability that affected the Verizon Wireless site is exceedingly common and will remain so as long as companies face no legal liability when they fail to secure customer data.
"There are probably tons of other big companies who have the same problems, because this is a really common mistake," Schneier said. "But if 15 million people can sue Verizon when they make a sloppy mistake like this, then it becomes an expensive mistake. Right now the only thing that happens to Verizon is they have a somewhat bad public-relations day."