International Business Times: Yahoo has shut down a cyber hack attack that exploited the company’s ad network for a full week to deliver malware directly to the computers of users who visited the company’s websites, the cyber security firm that discovered the attack said. Yahoo did not reveal how many users were affected, but it could be substantial, given that Yahoo gets 6.9 billion visits a month. The so-called “malvertising” attack is believed to be one of the biggest in recent times due to the massive amount of traffic Yahoo generates.