The FIFA World Cup 2014 begings June 12 and enthusiasm about the event has shown itself in increased traffic to different sport websites around the world. With more people visiting certain websites, you can bet that malicious individuals will look to take advantage. Traffic can easily translate to money, and we've discovered a malicious advertising banner hoping to cash-in on increased traffic to a sports website that's popular in Brazil.
Just about a month ago Kaspersky reported an exploit that was abusing a zero-day in Adobe Flash Player (CVE-2014-0515). We recently observed the use of this zero-day in attempts to deliver malware to our customers. After some further analysis, we came across the malicious advertisement (malvertising) on the website.
This site's ad provider is redirecting users to "ib.adnxs.com" a domain associated with previous malvertising campaigns. The site owners were notified and are taking measures to resolve the issue.
The samples we observed were placed on a public service for SWF hosting (www.swfcabin.com). The campaign is obviously a work in progress because we see newer samples protecting against decompilation of the ActionScript code by "SWF Defender" (a commercial obfuscator for SWF files). The earliest sample we observed was uploaded on May 14 and the latest on May 22.
We also noted that the attackers didn't just copy-paste the original code. Attackers behind this campaign employ the already known and widely used technique of corrupting AS vector size value in order to read the full address space. Unlike the original sample of CVE-2014-0515 where the attackers corrupt a Sound object vftable, however, they choose the FileReference object in this case.
Discussed malicious URLs can be found here: http://pastebin.com/TfgnyE0K
All customers of Trustwave SWG are protected against this threat without any additional updates.
Special thanks to my colleague Ben Hayak for helping with this blog.