Next Generation Of Exploit Kit Detection By Building Simulated Obfuscators ∗ Tongbo Luo Xing Jin Palo Alto Networks Inc Palo Alto Networks Inc 4401 Great America Pkwy 4401 Great America Pkwy Santa Clara, CA 95054 Santa Clara, CA 95054
[email protected] [email protected] ABSTRACT web attack. The earliest hack toolkit, named Mpack, was Recently, drive-by downloads attacks have almost reached available in the crimeware market in 2006. From then on, epidemic levels, and exploit-kit is the propulsion to signify exploit kits have become the most popular method for cyber- the process of malware delivery. One of the key techniques criminals to compromise hosts and to leverage those hosts used by exploit-kit to avoid firewall detection is obfuscat- for various methods of profit. Exploit kit can cost anywhere ing malicious JavaScript program. There exists an engine between free to thousands of dollars in underground market. in each exploit kit, aka obfuscator, which transforms the Typically, relatively unsophisticated kit may cost US$500 malicious code to obfuscated code. per month. Licenses for advanced kits have been reported In this paper, we tracked and collected over 20000 obfus- to cost as much as $10,000 per month. Currently, there are cated JavaScript samples of 5 exploit kit families from 2014 70 different exploit kits in the wild that take advantage of to 2016. This research is the first attempt to approach the more than a hundred vulnerabilities [1]. problem from a different angle: reverse engineering the ob- A key characteristic of an exploit kit is the heavily obfus- fuscator from obfuscated samples.