Another Yahoo mail account pwned

This is getting ridiculous. I don’t monitor Yahoo or other freemail accounts in any way, but it’s seems like almost every week I come across one that’s been taken over by criminals.  I got another email this morning from the account of an old friend sent by Yahoo webmail. He’s a a BT Internet customer, and I’ve no doubt from some features on it that it was sent out by someone sitting at a web browser, logged in as him. It wasn’t him, unless he’s moved to Hyderabad and taken up a life of crime – unlikely, he’s a retired fire officer in the north of England, and it’s not his style.

Yahoo obviously provides BT’s email service, so their customers get a Yahoo webmail account, like it or not.

This happens to other freemail users too, but the number of Yahoo accounts being hit is getting disproportionately ridiculous. Yahoo would need more customers than everyone else put together if this was just a random effect.

So what is going on? My assumption in cases like this is usually that the compromised accounts have been as a result of key loggers at Internet cafes or public Wi-Fi systems. It makes sense, and fits the facts in cases I’ve investigated. But not this time…

Earlier this year there was a problem with Yahoo involving cross-site scripting that could affect insecure web browsers (that includes all of the commonly used web browsers).  A character called Shahin Ramezany uploaded a video to YouTube  showing how to do this. Yahoo very quickly came back with a fix. They said. This just the latest in a long time of embarrassing problems – in Summer last year someone broke in to their computers and pinched a lot of confidential files.

Researchers at Bitdefender have also worked out how do to this, and it’s unclear whether Yahoo really has fixed the problem. For technical details, see CVE-2012-3414. It works by cookie harvesting, taking advantage of the way cookies are shared between different levels of a domain path.

Either this remains very much a problem, six weeks after Yahoo claimed to have fixed it, or the criminals have a large backlog of compromised user accounts and they’re just working through them. Users of freemail beware – how well do you think, with the best will in the world, that their operators will be able to provide technical assistance to hundreds of millions of advertising-supported punters?

If you have a Yahoo or BT Internet account, my advice is to log in and change the password right now, if you want to keep it.

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