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Privacy hole found in Verizon Wireless Web site

By Dan Verton
September 6, 2001 12:00 PM ET

Computerworld - Security experts discovered a flaw this week in the Web site operated by Verizon Wireless that potentially exposed the private customer information of those who used the Web site to view their personal cell phone bills.

Marc Slemko, a Seattle-based software developer, posted the warning Sept. 1 on the BugTraq security mailing list after notifying Verizon of the problem on Aug. 19 and receiving no response. Half a dozen other security experts later confirmed his findings.

The privacy hole affected users who logged on to the Verizon Wireless Web site and used the My Account feature to view or change their cell phone billing and account information. The Web site address for the feature assigns session identifications sequentially as each user logs in. The IDs are valid until the user logs out or the session times out. However, because it's the only session ID used, Slemko said it's easy to manually access the account of other users by guessing their session IDs. In addition, "automated tools [can] grab this information in bulk as users login over time," he wrote.

The vulnerability put at risk such information as names, addresses, records of calls placed and received, along with the phone number and approximate location of the user when the call was made, according to Slemko and others.

Brian Wood, a spokesman for Bedminster, N.J.-based Verizon Wireless, said IT workers at the company fixed the hole as of 5 a.m. EDT yesterday. When asked why it took Verizon so long to act on Slemko's Aug. 19 alert, Wood said Slemko didn't properly "escalate" his query.

"You have five different options to contact us on the Web site. His e-mail apparently went into the normal e-mail box and was handled by a front-line customer service representative," said Wood. "It kind of got bogged down in the system." However, Wood also said previous security tests run by Verizon on the site hadn't uncovered the flaw.

Wood said the flaw affected only a portion of the users who signed up for online billing. The hole was never an issue for former customers of Bell Atlantic Mobile, GTE Wireless, AirTouch Cellular or PrimeCo Personal Communications -- the companies that now make up Verizon Wireless.

"We've not seen any evidence that someone might have taken advantage of this hole," he said.

However, Verizon, which serves more than 28 million wireless customers, isn't alone in suffering from predictable online session IDs, according to a study presented at last month's 10th annual Usenix security conference by Kevin Fu and two other researchers at the MIT Laboratory for



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