The main Web site of MasterCard was knocked offline today in a large distributed denial of service (DDoS) attack apparently launched in retaliation for the credit card company's decision this week to cut off services to WikiLeaks.
Similar, much smaller attacks have also been detected against numerous other sites, including those belonging to U.S. Sen. Joseph Lieberman (I-Conn.) and former Alaska Gov. Sarah Palin, according to security researcher Sean-Paul Correll of PandaLabs. Correll has been maintaining a frequently updated blog on the unfolding attacks.
Also targeted have been the Web sites of Swiss payment transaction firm PostFinance, as well as PayPal and EveryDNS , all three of whom terminated services to WikiLeaks after the site began publishing thousands of leaked U.S. State Department cables last week.
In addition, DDoS attacks have been launched against the Swedish prosecutors who are pursuing rape charges against WikiLeaks founder Julian Assange. The site of the lawyer representing the two women who were allegedly assaulted by Assange was also hit, Correll said today.
The attacks have resulted in varying degrees of downtime for the targeted Web sites. MasterCard's site, for instance, has been largely unavailable since the DDoS attacks against it began shortly after 4 a.m. ET, Correll said. And the attacks against PostFinance have so far resulted in more than 33 hours of downtime for the firm.
In a brief statement, MasterCard this afternoon said it has made "significant progress" in restoring full service to its corporate site. Despite "limited interruptions," cardholders can continue to use their Mastercards securely, the company said. "Our core processing capabilites have not been compromised and cardholder account data has not been placed at risk."
Another site that was hit was Visa, which appears to have suffered an attack around 4 p.m. ET. It was not clear whether Anonymous is behind that attack, Correll said.
However, the attacks against Lieberman's Senate site and Palin's sarahpac.com appear to have caused much less disruption. According to statistics on Correll's PandaLabs blog, Lieberman's site was down for barely 12 minutes, while Palin's was knocked offline for about 25 minutes.
An anonymous, loosely affiliated group of hackers and activists, calling themselves Anonymous, claimed responsibility for the attacks against MasterCard and the others. The organizers of the group have an ongoing campaign called Operation:Payback that is focused on attacking entertainment industry Web sites over copyright enforcement issues.
Earlier this week, the group announced its support for WikiLeaks and announced Operation:Avenge Assange, which is targeted at "entities involved in censoring [WikiLeaks'] information."
The group has made available a DDoS tool called the Low Orbit Ion Canon that just about anyone can use to participate in a DDoS attack. According to Correll, the tool gives users an easy way to hook their computers into a voluntary botnet of systems participating in a DDoS attack against specific targets at any given time.
Earlier this morning, a "voluntary botnet" of about 1,700 computers involved in the attack against MasterCard, Correll said. The group's member base appears to be growing, with about 2,200 participants present in an Anonymous chat room earlier today, more than double the 1,000 or so involved yesterday, Correll said. In some cases, in addition to the DDoS attacks, the group has resorted to Black Fax-ing, a practice in which a black sheet of paper is repeatedly sent to a fax recipient in order to deplete the machine's toner cartridge.
Meanwhile, Anonymous' own Web site, anonops.net , has been hit with massive counter-DDOS attacks and has been down intermittently the past few days, he added. Anonops.net is hosted by a Russian ISP.
Chet Wisniewski, a security researcher with Sophos Labs today said DDoS attacks continue to be the weapon of choice because they are relatively easy to pull off but hard to defend against.
DDoS attacks work by overwhelming targeted Web sites with useless traffic, rendering them inaccessible to others. One of the most effective ways of countering such attacks is by filtering out the useless traffic before it reaches the target, Wisniewski. Attack traffic such as that generated by Anonymous' relatively unsophisticated Low Orbit Ion Canon can be relatively easy to spot and block, he said.
Often, the impact of such attacks is less dramatic than it might appear. For instance, while MasterCard's main site may have been taken down today, none of the company's core business transactions have been touched, Wisniewski said.
For the attackers, "this is another form of political protest, even though it is criminal and something uncalled for," he said.