Despite the incarceration of founder Julian Assange, WikiLeaks is not going away quietly. In fact, Web-savvy supporters of the online whistle-blowing operation have gone on the offensive, launching cyber attacks against Web sites of some of the organizations and people perceived to have wronged Assange and his operation.

Mastercard, which earlier this week announced it would not enable payments to WikiLeaks via its credit-card processing systems, has had its Web site rendered inaccessible several times in the past day. Visa made a similar announcement, and its Web site was likewise down Wednesday afternoon. PayPal, which ended its affiliation with WikiLeaks, was up and running as of post time, but cyber security firm PandaLabs reports that has experienced 77 interruptions equaling a total downtime of more than eight hours in the past 24 hours.

Attacks on sites connected to WikiLeaks opponents or critics (not counting MasterCard or Visa) have created 256 interruptions of service and a total of 94 hours of downtime in the past day, according to PandaLabs. Other sites recently downed by cyber attacks, according to PandaLabs, include those run by Sen. Joseph Lieberman (outspoken in condemning WikiLeaks's "cablegate" campaign), Sarah Palin (who likened Assange to a terrorist) and Claes Borgstrom (the lawyer representing the two girls who claim Assange sexually assaulted them this the summer). Assange is currently jailed in England and has been denied bail.

A movement calling itself Operation: Payback, a campaign headed by an anonymous group "against major anti-piracy and anti-freedom entities," is taking credit for much of the digital mayhem. Ironically, the Web site, which is linked to Operation: Payback's Twitter page, was likewise inaccessible Wednesday afternoon. Operation: Payback has made a name for itself in recent months by launching cyber attacks against organizations opposed to intellectual property piracy, including the Motion Picture Association of America (MPAA) and the Recording Industry Association of America (RIAA). They now obviously have a new cause.

The most recent attacks against organizations opposed to or distancing themselves from WikiLeaks follow last week's attacks against WikiLeaks's own Web site. One attacker took down the site for a 28-hour period on November 30 and December 1, according to PandaLabs security analyst Sean-Paul Correll.

The weapon of choice in these cyber salvos is the distributed denial-of-service attack (DDOS), in which computers are programmed to flood Internet servers for sites with requests for data to the extent that those servers cannot function. These computers are often enlisted by malicious hackers without the knowledge of the computers' owners.

Operation: Payback logo courtesy of