The websites of the Information Commissioner's Office (ICO) and Home Secretary Theresa May have been taken down as part of a distributed-denial-of-service (DDoS) campaign.

According to Techweek Europe, the attacks were carried out by an Anonymous splinter group named‘ATeam' who were protesting against the proposed extradition of Gary McKinnon and Richard O'Dwyer to the US.

May's website went down from around 9pm on Sunday for around 13 hours; the website of the Supreme Court was also pushed offline, with the ICO site still down at the time of writing.

A spokesman for May told Techweek Europe that she "treats threats of disruption to her website very seriously".

The ICO has confirmed that it is looking into the matter with the provider of its web hosting. In a statement, it said: “Access to the ICO website has been disrupted over the past few days. We believe this is due to a distributed-denial-of-service attack.

“The website itself has not been damaged, but people have been unable to access it. We provide a public-facing website which contains no sensitive information.

“We regret this disruption to our service and we are working to try to bring the website back online as soon as possible.”

André Stewart, president international at Corero Network Security, said: “The takedown of the ICO website by an apparent DDoS attack is, once again, evidence that government organisations need to be better prepared for the growing threat from cyber crime carried out by politically or ideologically motivated hacktivists.

“Virtually every week we are seeing DDoS attacks being launched. Organisations of all types need to start planning accordingly in terms of putting the right technology and protocols in place to protect themselves and their constituents and customers against these forms of attack, before a more serious data breach occurs.”

A new botnet has been detected that steals passwords and login credentials, with more than 100 financial and banking domains targeted.

Named the ‘Jericho' botnet, it was detected by Palo Alto Networks, which claimed to have discovered 42 samples of it and said it is a variant of banking Trojans such as the stealthy Jorik.

Palo Alto said its WildFire detection network found the unique but related banking botnet samples. It also said that all infections were delivered from Israeli IP space, but the engineering of the file appears to be of Romanian origin; as the vast majority of the URLs used to deliver the malware ended in ierihon.com (Ierihon means “Jericho” in Romanian), it was named the Jericho botnet.

“But what's really interesting about Jericho is that like many other contemporary pieces of modern malware, Jericho demonstrates a number of behaviours that are designed for stealth, persistence and avoidance of traditional signature-based approaches to malware detection,” it said.

“The malware is able to inject itself into the Windows logon to maintain persistence on the infected host after a reboot. What was a bit more interesting was just how efficient the malware was at injecting itself into valid applications such as Firefox, Chrome, Java, Outlook and Skype, and then repurpose their capabilities. This not only enables the malware to hide within approved applications during run time, but it also means that standard methods for observing Windows API calls are subverted.”

It also claimed that of the 42 samples that were analysed, the top anti-virus solutions only achieved a 3.2 per cent detection rate on the day the sample was first detected. This slowly but steadily improved over time, with coverage improving to 39 per cent over seven days.