Federal investigators have seized servers allegedly abused to launch a denial of service attack against PayPal earlier this month.

An affidavit obtained by the Smoking Gun contains testimony by federal agents convinced that systems at Texan hosting firm Tailor Made Services are likely to contain clues in the hunt for hacktivists who launched an attack against PayPal in response to its decision to freeze an account used by WikiLeaks. The suspension of the account followed the release of US diplomatic cables by the whistle blowing site.

Volunteers were encouraged by members of the loosely bound Anonymous collective to download a tool to pepper the websites of financial firms who had turned their back on WikiLeaks - including MasterCard, Visa and Swiss bank PostFinance as well as PayPal - with junk traffic.

FBI investigators are proceeding on the assumption that some used botnets of compromised machines in order to launch a more potent distributed denial of service attack against PayPal, knocking its corporate blog offline for at least several hours.

PayPal supplied FBI agents with eight IP addresses of systems used to run IRC chat servers associated with planning the so-called Operation Avenge Assange attacks. Investigators reckon the same systems were also used as command and control hubs for botnets used the DDoS assault against PayPal et al.

The Texan systems were traced back via a compromised machine at Host Europe, Germany. Investors alleged that the command to launch an attack against PayApl was made via systems hosted by Tailor Made Services in Texas and relayed via the servers at Host Europe in a bid to disguise its origin. A pair of log entries on the compromised Host Europe machine contained the same message: "Good_night,_paypal_Sweet_dreams_from_AnonOPs." according to a sworn statement from FBI agent Allyn Lynd.

The affidavit was used to obtained a search warrant used on a raid on Tailor Made Services on 16 December. Agents copied two hard drives from the targeted server during this raid. A second IP address associated with the pro-WikiLeaks attacks was traced to a virtual server physically hosted by Hurricane Electric in California.

It's unclear whether or not a suspect has been identified through the FBI's investigation thus far. ®