Cyber criminals are launching malvertising attacks on major legitimate ad networks like ad.yahoo.com in an attempt to spread malware to unsuspecting users, according to security and networking solution provider Blue Coat Systems.
Malvertising is the use of online advertising to spread malware – in this case, criminals are infecting computers with CryptoWall, a ransomware that encrypts a user's documents and demands financial payment for unlocking and return.
Over several weeks Blue Coat security researchers tracked malicious traffic involved in a CryptoWall ransomsware campaign.
According to Chris Larsen, architect of Blue Coat's threat research team, what looked like "minor" malvertising attacks took a sinister turn as cyber criminals gained the trust of major ad networks like ads.yahoo.com.
"The interconnected nature of ad servers and the ease with which would-be-attackers can build trust to deliver malicious ads points to a broken security model that leaves users exposed to the types of ransomware and other malware that can steal personal, financial and credential information," he said.
Earlier this year CRN reported on a malvertising campaign that targeted a popular Brazilian sports new site in an attempt to profit on the FIFA World Cup tournament, as discovered by Trustware's research team SpiderLabs.
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