A faction of the rogue Anonymous movement temporarily disrupted the online presence of several major banks with an onslaught of distributed denial of service (DDoS) attacks.
Among the targets of the group identifying itself as Anonymous Brasil were Citibank and HSBC, as well as multiple South American financial institutions including Banco BMG, Banco Bradesco, Banco Panamericano, Itau Unibanco Banco Multiplo and Febraban.
In denial of service attacks, generally a large amount of information is sent to a web server at such high frequency that it overwhelms the processing capacity or causes the system to shut down and reset altogether.
The net effect is that the server can not longer operate correctly and the targeted website is rendered unusable for its primary purposes, such as for customer interface or sales.
Denial of service attacks attacks are low-tech, and the majority of internet servers are vulnerable to the attack method, which makes the tactic increasingly popular.
The latest attacks come just a few weeks after after multiple DDoS attacks were launched against entertainment industry and US government websites by Anonymous supporters in an operation dubbed "OpMegaupload".
The attacks caused disruptions for several websites, including those operated by the Justice Department, the FBI, the US Copyright Office, Universal Music, BMI, and the RIAA.
OpMegaupload was a response to Justice Department indictments issued against executives at the file sharing website Megaupload.com for copyright infringement and piracy, as well as in general opposition to the Stop Online Piracy Act (SOPA) and the Protect Intellectual Property Act (PIPA) legislative bills currently being considered by Congress.
The crowd-sourced DDoS attacks quickly diminished, but US-CERT subsequently received reports of attacks using emails designed to infect systems by way of malware-laden attachments, and advised government agencies and the private sector to be vigilant against the continued threat of denial of service attacks.