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
Anyone can purchase an exploit pack (EP) license or rent time on an existing EP server. The challenge for threat actors is to redirect unsuspecting web browsing victims by force to the exploit landing page with sustained frequency. Naturally, like most criminal services in the underground, the dark art of traffic generation is a niche specialty that must be purchased to ensure drive-by campaign success. For the past year we have been tracking a threat actor (group) that compromises legitimate websites and redirects victims to EP landing pages. Over the past three months we observed the same actor using malvertising -- leveraging content delivery networks (CDNs) to facilitate increased victim redirection -- as part of larger exploit pack campaigns. Read More »