As part of Operation Payback, volunteers have stepping forward to help target anti-WikiLeaks organizations with distributed denial of service (DDoS) attacks run via botnet. One related toolkit has already been downloaded 50,000 times.

Typically, botnets employ surreptitiously compromised PCs to launch attacks aimed at stealing people's personal financial information. But in this case, botnets are being used to trigger the PCs of volunteers into flooding designated sites with packets, en masse. While Amazon.com has repulsed related DDoS attacks against it, the Web sites of MasterCard and the Swedish Prosecutor's Service have suffered outages.

The attack code, known as Low Orbit Ion Cannon, comes in three flavors: manual, server-controlled, and a JavaScript version -- known as JavaLoic -- that requires no download. According to Vanja Svajcer, principal virus researcher at SophosLabs, the application includes a "Hive Mind" feature that connects to an IRC channel for coordinating the attack. Interestingly, the application itself is open source, was written in C#, and is hosted on major open source code repositories, including Sourceforge.

"The main purpose of the tool, allegedly, is to conduct stress tests of the Web applications, so that the developers can see how a Web application behaves under a heavier load," said Svajcer. "Of course, a stress application, which could be classified as a legitimate tool, can also be used in a DDoS attack."

Numerous people have downloaded -- and are apparently using -- the software. By Thursday, "for the server-controlled version, there have been already 33,000 downloads at a rate of more than 1,000 downloads per hour," said Rob Rachwald, director of security strategy at Imperva. By Friday, the manual version of the malware had been downloaded 50,000 times.

Thinking of enlisting? "Stay well away," said Graham Cluley, senior technology consultant at Sophos. He said that laws in the United Kingdom punish such attacks with up to 10 years in prison, while Sweden and the United States have similar laws on the books.

To that list, add the Netherlands. On Thursday, Dutch police officers arrested a teenager in The Hague. They said he admitted to participating in pro-WikiLeaks attacks against the MasterCard and Visa Web sites.

As that suggests, attacks can be traced back. "Many people believe that privacy on the Internet can be somewhat protected, but beware, the source IP addresses of attackers, which will inevitably end up in the target's Web site log files, can easily be matched with user's accounts if ISPs decide to cooperate with the law enforcement agencies," said SophosLabs' Svajcer.