This post is co-authored by Andrew Tsonchev, Jaeson Schultz, Alex Chiu, Seth Hanford, Craig Williams, Steven Poulson, and Joel Esler. Special thanks to co-author Brandon Stultz for the exploit reverse engineering.
Silverlight exploits are the drive-by flavor of the month. Exploit Kit (EK) owners are adding Silverlight to their update releases, and since April 23rd we have observed substantial traffic (often from Malvertising) being driven to Angler instances partially using Silverlight exploits. In fact in this particular Angler campaign, the attack is more specifically targeted at Flash and Silverlight vulnerabilities and though Java is available and an included reference in the original attack landing pages, it’s never triggered.
HTTP requests for a specific Angler Exploit Kit campaign
Angler exploit content types delivered to victims, application/x-gzip (Java) is notably absent
This post was also authored by Andrew Tsonchev and Steven Poulson.
Update 2014-05-26: Thank you to Fox-IT for providing the Fiesta logo image. We updated the caption to accurately reflect image attribution.
Cisco’s Cloud Web Security (CWS) service provides TRAC researchers with a constant fire hose of malicious insight and now that we are collaborating with Sourcefire’s Vulnerability Research Team (VRT) we have additional capabilities to quickly isolate and prioritize specific web exploit activity for further analysis. Thus when we were recently alerted to an aggressive Fiesta exploit pack (EP) campaign targeting our customers, we quickly compared notes and found that in addition to the typical Java exploits, this EP was also using a Microsoft Silverlight exploit. In the Cisco 2014 Annual Security Report (ASR) we discuss how 2013 was a banner year for Java exploits, and while updating Java should remain a top priority, Silverlight is certainly worth patching as threat actors continue to search for new application exploits to leverage in drive-by attacks.
Image provided courtesy of Fox-IT
Over the past 30 days this specific Fiesta campaign was blocked across more than 300 different companies. The attacker(s) used numerous dynamic DNS (DDNS) domains -- that resolved to six different IP addresses -- as exploit landing pages. The chart below depicts the distribution of hosts used in this attack across the most blocked DDNS base domains.