For the aspiring attacker or pen tester, there is no shortage of attack tools, scripts, crimeware kits and exploits available online. But, the Internet being what it is, there’s always room for one more. Enter HULK, a new DDoS tool that arrives just in time to coincide with the release of some movie involving the actual Hulk and other CGI-ified mediocre-heroes.
The HULK (HTTP Unbearable Load King) DDoS tool is somewhat different from others of its ilk in that it doesn’t simply hammer a server with a massive load of TCP SYN requests or other predictable packets. Instead, HULK generates numerous unique requests designed to prevent server defenses from recognizing a pattern and filtering the attack traffic. The HULK DDoS tool is the work of Barry Shteiman, a security pro who developed it out of frustration with the obvious patterns produced by other such tools.
“For a while now, I have been playing with some of the more exotic tools, finding that their main problem is always the same… they create repeatable patterns. too easy to predict the next request that is coming, and therefor mitigate. Some, although elegant, lack the horsepower to really put a system on its knees,” he wrote in his notes on HULK.
“Enforcing Python’s engines, I wrote a script that generates some nicely crafted unique Http requests, one after the other, generating a fair load on a webserver, eventually exhausting it of resources. this can be optimized much much further, but as a proof of concept and generic guidance it does its job. As a guideline, the main concept of HULK, is to generate Unique requests for each and every request generated, thus avoiding/bypassing caching engines and effecting directly on the server’s load itself.”
In order to confuse the target Web server as thoroughly as possible, Shteiman has included a number of different features in HULK, including the ability to hide the actual user agent and obfuscate the referrer for each request. In his own tests, Shteiman said that the attack tool had no trouble taking down a target server within a minute or so.
“Basically my test web server with 4gb of Ram running Microsoft IIS7 was brought to its knees under less than a minute, running all requests from a single host,” he said.