Yahoo has suffered from a malware attack causing malicious advertisements showing on the screens of 27,000 users per hour.
Fox-IT, an Internet security firm, exposed that Yahoo has been under a malware attack in the past few days and it is affecting users in different countries.
According to the firm's blog post, those who are visiting the site have received advertisements provided by ads.yahoo.com. However, some of those ads are malicious and can install a host of a variety of malwares and can exploit vulnerabilities in Java.
The firm estimates that thousands of Yahoo users were affected per hour.
"Given a typical infection rate of 9 percent this would result in around 27,000 infections every hour. 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," said in the blog post.
The company advised Yahoo users to block the IP-addresses of the exploit kits -- 192.133.137/24 and 193.169.245/24 - and "closely inspect network traffic for signs of successful exploits for any of the dropped malware."
However, the security firm isn't sure who or what group performs the attack but is quite sure that the attackers are "financially motivated."
Yahoo is aware of the adverse events and is keeping an eye on and blocking malicious advertisements.
"At Yahoo, we take the safety and privacy of our users seriously," the company said in a press release on late Sunday. "On Friday ... on our European sites, we served some advertisements that did not meet our editorial guidelines, specifically they spread malware. We promptly removed these advertisements."
"Additionally, users using Macs and mobile devices were not affected," it added.
