Distributed denial of service attacks, of the kind pro-Wikileaks hacktivists have been aiming at PayPal, Visa, and MasterCard, are not particularly complex to pull off.

You need a lot of individual computers sending server requests to the site in question, enough to overload the site. The hacktivists have been using Twitter to coordinate those attacks. And Twitter, it seems, may have been trying to shut them down.

According to tweets, accounts named @Anon_Operation and @AnonOperation went down yesterday. ("Anonymous" is the name of the underground organization leading the DDoS attacks.) They currently appear to be back up. Either way, new accounts have emerged to take their place, such as @Op_Payback and @AnonOpsNet.

The accounts are letting the thousands of hactivists around the world know which site is the target of choice at the moment. Since the server requests have to happen all at the same time, real-time communication is paramount. Yesterday's target was Visa. Midday Thursday, east coast time, the target of choice was PayPal. Both companies have cut Wikileaks off.

Twitter declined to comment, telling Fast Company via email: "We don't comment on actions we take against individual user accounts." But its Terms of Service say users have to abide by "local, state, national, and international laws, rules and regulations." Denial of service attacks violate those laws. Indeed, on Thursday, Dutch police arrested a 16-year-old boy for participating in the attacks.

Hacktivists don't seem to be as put out by Twitter potentially shutting down their accounts as they were earlier this week, back when they thought Twitter was censoring #Wikileaks and related hashtags from its Trending Topics lists. Twitter replied to those concerns with a post on its blog today, explaining that the lists are based on what's "emerging", not what's most popular at any given time.

Republished with permission from FastCompany.com. Authored by E.B. Boyd.