DDoS Botnet Now Can Detect Denial-Of-Service Defenses

Bad news for DDoS mitigation methods: A new version of an infamous distributed denial-of-service (DDoS) toolkit can check victims' networks for DDoS mitigation methods so it can circumvent those defenses.

DirtJumper Drive, a DIY kit that makes it easy for anyone to create their own botnet to DDoS a target, has been evolving over the past year. This summer, Arbor Networks' ASERT team discovered that the malware had begun to obfuscate its communique with bots. Now DirtJumper Drive is fighting back against DDoS mitigation services.

"We found one attack that was searching for DDoS mitigation techniques and trying to actively bypass those so it can get through to its target and get the target down," says Jason Jones, a security research analyst with ASERT. The attack appeared to be against a financial industry organization, he says.

"This time, they are definitely going after us and others in the DDoS mitigation space. I want to make sure we share enough information, samples, and future [ways] to identify it ... It's definitely a step up in the protection game for us," he says.

It also signals a turning point in DDoS attacks. "Historically, DDoS malware has not been as sophisticated as other malware and not as advanced," he says. "It will be harder to detect."

DirtJumper, which was created by a Russian-speaking malware writer allegedly known as "sokol," can cost as little as $150 in the underground, according to DDoS mitigation provider Prolexic.

The new version discovered by Arbor's ASERT team has three other attacks in addition to the so-called "-smart" attack that sniffs out and bypasses DDoS defenses. Among those features is an ICMP attack and an attack that extends the amount of time a connection is kept open. The "–smart" attack module detects and cheats anti-DDoS cookies, redirection methods, and metatags used for redirecting malicious IP traffic. Jones says Arbor is countering the new botnet feature with special rules for DirtJumper Drive that prevent it from getting past its mitigation services.

The attack basically looks for a "Set-Cookie" or a "Location" header and "will parse out either the Cookie value or new URL location use those values in the next packet it sends. It will also look for a meta equiv refreshtag, location= or document.location.href inside of the response from the server," Jones wrote in a blog post about the attacks that will post later tonight. "This is one of, if not the, first pieces of DDoS malware that ASERT has seen actively attempt to defeat known mitigation techniques."

And this won't likely be the last advanced version of the malware to emerge. The "rapid evolution and dissemination of different Dirt Jumper variants is the best proof of its wide acceptance as one of the main tools in today’s botnet-for-DDoS market," said Toronto-based researchers at York University in a academic paper (PDF) on the botnet published late last year.

DDoS attacks can be financially crippling. A 24-hour outage due to a DDoS can result in a loss of around $27 million, or $2.1 million for a four-hour website outage, according to Forrester Research. Financial services firms lost some $17 million per DDoS attack last year, Forrester estimates.

[Researchers demonstrate how ads invoking JavaScript on viewers' browsers en masse could create untraceable networks to wreak DDoS damage. See Creating Browser-Based Botnets Through Online Ad Networks .]

Dell SecureWorks, which announced today that it is seeing hacktivists employing other methods in addition to DDoS, recommends employing a bogus IP address block list at the network perimeter to keep DDoS IP traffic out. Separating critical services, such as HTTP, FTP, and DNS, and setting up a dedicated firewall for each and running load-balancers can help as well, the company says.

"Evaluate and implement dedicated DDoS mitigation technologies. Having dedicated hardware for mitigating DDoS and DoS-styled attacks can help keep strain off targeted systems and provide your DDoS response team with much needed time to find and eliminate the attack," according to a Dell SecureWorks advisory posted today.

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