DDOS Botnets Thriving, Threatening

U.S. researchers are closely tracking several Russian botnets that have hammered Eastern European e-commerce and government-related Websites with distributed denial-of-service (DDOS) attacks over the past year -- and they worry that larger, politically inspired DDOS attacks may be on the horizon.

The botnets use inconspicuous HTML Web-based communications to issue their bot commands to the infected clients they use for their attacks. They deploy the so-called Machbot, Barracuda, and BlackEnergy bot code packages, according to the researchers.

"We've been getting our hands around the IRC [Internet Relay Chat] botnets, but the landscape is changing" with Web-based and peer-to-peer botnets, says Jose Nazario, senior security engineer for Arbor Networks. "And it appears political DDOS attacks are here to stay."

Nazario says when Estonia suffered its DDOS attacks last year, he initially wasn't as alarmed as some experts were at the prospect of such a political attack catching on internationally. "I was more cautious and wasn't sure. But [this form of attack] appears to be continuing and could be sneaking up on the world," he says.

Such botnets could be used to wage large-scale DDOS attacks, and would be tough to investigate because they crisscross international borders, Nazario notes.

Danny McPherson, Nazario's colleague and chief research officer at Arbor Networks, next week will brief officials from the U.S. Department of Defense, defense contractors, law enforcement, and other attendees at The Department of Defense Cybercrime Conference on Arbor's research on the potential threats posed by these DDOS botnets.

"The key is their maturation and the new ground they are exploring," Nazario says. "I don't want to say the sky is falling and we're doomed. But it's hard to tell where political DDOS[ing] is going to go."

Arbor so far hasn't seen any U.S. government agencies targeted by a DDOS attack or a related botnet infection. But unless an agency deploys strict URL sensoring, Nazario says, a client machine inside a government office could potentially be at risk of infection from one of these flavors of DDOS bots. "The issue becomes how do you detect this… This is a slightly stealthier bot. You would have to know what URLs to block."

These bots are tougher to detect because they communicate in HTML, which doesn't draw the red flags IRC communications do. The infected client machines check in with their command-and-control Websites, where they are either updated with new software or ordered to DDOS a site, Nazario says. The good news is that their commands are encoded, but not encrypted, so their messages can be easily decoded by researchers, he says.

Clients get infected either via infected legitimate or malicious Websites with "drive-by" Trojans. "For the most part, they are pure DDOS tools, with no exploits built in, and they aren't scanning the network" or anything like that, Nazario says. Their architecture is aimed at evading antivirus and IDS/IPS scans, he says.

There are around 12 Machbot-based DDOS botnets -- it's used less frequently than others but packs a more powerful punch, according to Arbor. The company is also watching Barracuda bot code on about six botnets, and the more prolific BlackEnergy, a commonly used DDOS kit that's being used by several DDOS botnets. BlackEnergy costs only about $40 for the binary code, and it includes a rootkit that hides the bot code, as well as tools to control the botnet Website.

So far, the botnets have launched DDOS attacks against a variety of targets, including small ecommerce sites, rival botnets, investigators on their trail, and of course, political Websites.

Usually, though, these botnets have targeted ecommerce sites in Eastern Europe, Nazario says, noting that it's unclear whether these botnets are controlled by small groups in Russia or even by a political party. The DDOS botnets aren't necessarily the largest botnets, either: They range in size from dozens of machines to several thousand, according to Nazario.

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