Spam campaigns based on the Blackhole Exploit Kit send messages that contain links to compromised legitimate websites, which serve hidden iframes and redirections that exploit vulnerabilities across operating systems–from Android to Windows. Spam themes we have seen vary rapidly and are disguised to appear as legitimate messages from familiar services. Campaigns spoofing Facebook, LinkedIn, American Airlines, and various banking services carry embedded links to malware. Spammers abuse email templates from familiar service providers by capturing automated emails, replacing links in the template with links to malware, and rebroadcasting those messages to harvested or predicted recipients.
This tactic has proven effective for spammers. Recipients are likely to click links in familiar-looking emails and often create custom whitelist entries for common sending domains without enforcing Sender Policy Framework or DomainKeys Identified Mail validation.
The Messaging Security Team at McAfee Labs has closely monitored this trend and would like to share a few common traits from recent campaigns to aid in identification
read more.........http://blogs.mcafee.com/mcafee-labs/blackhole-exploit-kit-spam-campaigns-disguised-as-top-service-brands