Yahoo Infects Thousands of Users After Massive Malware Attack

YahooA malware attack hit Yahoo’s advertising server over the last few days, affecting thousands of users in various countries, an Internet security firm said. In a blog post, Fox-IT said Yahoo’s servers were releasing an “exploit kit” that exploited vulnerabilities in Java and installed malware. “Clients visiting received advertisements served by,” the internet security firm said. “Some of the advertisements are malicious.” Fox-IT, which is based in the Netherlands, focuses on cyber defense. It estimates tens of thousands of users were affected per hour. “Given a typical infection rate of 9%, this would result in around 27,000 infections every hour,” the company said. “Based on the same sample, the countries most affected by the exploit kit are Romania, Great Britain and France. At this time it’s unclear why those countries are most affected, it is likely due to the configuration of the malicious advertisements on Yahoo.” If a computer infected with malware is connected to a network, attackers can often access other connected systems and servers.

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  1. deancollins says:

    hmmm not enough info to confirm but I suspect the servers haven’t been “hacked” but just that the ad banners are serving up malicious banners.

    its a common issue with ad-networks where they allow someone to bid on banner space….but then don’t pre-test it before serving the banner to visitors.

    We had this issue at a while back when we used OpenX as our ad server, this along with other vulnerabilities is one of the reasons we swapped out our ad server.

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