AT&T-iPad breach could be serious after all

Information exposed could give hackers access to more sensitive data

The breach of AT&T’s Web site that exposed the e-mail addresses and SIM card numbers of about 114,000 iPad 3G users was widely seen as an embarrassment to AT&T but not a serious threat to the users, which included a number of people in the federal government.

However, a number of security experts are now saying that the breach, reported in early June, could be much more serious than first thought. Taking advantage of the information exposed wouldn’t be easy – and there have been no reports that anyone has done so – but it is possible, the experts say.

A flaw on AT&T’s Web site allowed a group of hackers to reveal the e-mail addresses and Integrated Circuit Card identification numbers of the users, which included high-profile people in politics, media and business, along with users in the Defense Department and several civilian agencies. The ICC ID is the 19- or 20-digit serial number on a device’s SIM card that identifies devices such as cell phones and iPads on a network.

Previous stories:

AT&T-iPad data leak: Hack or hype?

Military, other fed iPad users compromised in AT&T hack

ICC IDs are not secret – they’re printed on the SIM card and sometimes on the boxes that a mobile device comes in – so their exposure in the breach was not considered serious. But the numbers do relate to another number, the International Mobile Subscriber Identity number, or IMSI, which is more sensitive.

The Wall Street Journal reported that IMSI numbers, the 15-digit numbers stored within the SIM card, are analogous to a driver’s license and are used to bill the user. “They identify users' home networks and link to databases containing personal details, such as name, address and phone number, and a device's latest location on the network,” the Journal said.

Law enforcement agencies also can use IMSI numbers to identify the users of mobiles devices, track suspects and listen in on their calls, the Journal said.

Although iPad users wouldn’t be making calls with their devices, the exposure of their IMSI numbers could let them be tracked, although most likely only down to the level of what city they were in, and could, in theory, expose an unencrypted data transmitted to or from the device.

Business Week reported that in 2008, security researcher Lee Reiber of Forensics Inc. documented how to extract an IMSI number from an AT&T ICC ID number. And InfoWorld cited a recent demonstration at the Source Boston conference on how to use IMSI numbers to derive the billing address, phone number and geolocation of mobile devices.

Ars Technica also reported that it could allow attackers to create fake cell towers and listen in to a user's calls and text messages.

Of course, tracking or eavesdropping on a device using a IMSI would require access to the mobile network they use. Police can get that via court order, but the Journal reported that a variety of communications companies have access to networks used for routing calls.

The hacker group that exposed the information on AT&T’s site said it was merely trying to reveal a flaw and that it did nothing with the information it found. However, the FBI has launched an investigation into the incident, which exposed information belonging to some famous people, such as New York City Mayor Michael Bloomberg, Diane Sawyer of ABC News, film producer Harvey Weinstein and White House Chief of Staff Rahm Emanuel.

Users at the Army, the Defense Advanced Research Projects Agency, the Federal Aviation Administration, the Federal Communications Commission, the Justice Department and NASA also were on the list of exposed e-mail addresses. Even if the group that exposed the data truly is benign, other hackers with less noble motives could conceivably exploit the same vulnerability.

Although the incident has so far been of no real consequence, security experts are recommending that users get new SIM cards from AT&T, to be on the safe side. The company recently said it would give a new card to any user who asked.

And considering the proliferation of mobile devices, all of which display their ICC ID numbers in one way or another, the incident could service as a cautionary tale, perhaps raising the question of whether providers need new ways of deriving the more sensitive IMSI numbers.


About the Author

Kevin McCaney is a former editor of Defense Systems and GCN.


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