Is your smartphone telling every website you visit your telephone number?

Graham Cluley
@gcluley

O2 mobile users in the UK are venting on Twitter today, fuming at their discovery that their phone number is being shared with every website that they visit over the network.

I found a colleague who owns an iPhone on the O2 network, and we tried it out for ourselves. Making sure we turned off his WiFi connection, we used the O2 mobile network to access the web.

Sure enough, his mobile number was being secretly communicated to websites he visited, embedded inside an http header called HTTP_X_UP_CALLING_LINE_ID.

O2’s response so far is to tell concerned Twitter users that it is investigating the issue.

Well, maybe I can be of some assistance. Because, although the problem is getting a lot of people’s attention today, it’s actually been known about for almost two years at least.

Back in March 2010, Berlin student Collin Mulliner revealed his discovery at the CanSecWest conference in Vancouver and…

Read more in my article on the Naked Security website.

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Graham Cluley is a veteran of the anti-virus industry having worked for a number of security companies since the early 1990s when he wrote the first ever version of Dr Solomon's Anti-Virus Toolkit for Windows. Now an independent security analyst, he regularly makes media appearances and is an international public speaker on the topic of computer security, hackers, and online privacy. Follow him on Twitter at @gcluley, or drop him an email.

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