A new report on malicious advertising underscores the importance of using modern web browsers and making sure your operating system is up to date with the latest security updates to prevent being infected. Malvertisers pushing exploit kits will show ads to Internet Explorer users as they target the browser’s vulnerabilities and ads pushing the Mac Shlayer Trojan will only show the ads to Mac users. Confiant Security researcher Eliya Stein explains that the malvertisers are not specifically targeting these two government agencies, but rather the technology that they use.
Source: https://www.bleepingcomputer.com/news/security/malvertising-in-govt-enterprise-targets-old-software-macs/