Public facing tax and benefits sites have been identified as possible targets for pro-Wikileaks reprisal attacks, the prime minister's office said on Monday.
Number 10 security adviser Sir Peter Ricketts wrote to government departments requesting a review of security procedures in the light of denial-of-service reprisal attacks by the Anonymous group, it emerged last week.
On Monday, the prime minister's office said that Ricketts had placed particular emphasis on the threat of distributed denial of service (Ddos) attacks on Her Majesty's Revenue and Customs (HMRC) and Department of Work and Pensions (DWP) websites.
"Asked if there were any plans to protect government websites, the [prime minister's spokesman] said that the national security advisor [Ricketts] had spoken to permanent secretaries about the security of government websites," said Monday's press briefing notes. "The priority would be websites that dealt with information that belonged to members of the public, such as the DWP and HMRC websites."
The spokesman declined to comment on the scale of the threat.
The Anonymous group has been carrying out a series of Ddos attacks against organisations that have frozen Wikileaks' funds, or pulled out of payments processing for Wikileaks donations. PayPal, MasterCard, and Visa have all declined to continue processing payments for Wikileaks, and have been the subject of Ddos attacks. Wikileaks is in the process of publishing hundreds of thousands of classified US government documents.
Anonymous launched a second Ddos attack against MasterCard on Sunday, which brought mastercard.com down, according to security company Netcraft.
The Anonymous group on Monday opened a second line of attack against organisations including MasterCard, Visa, and PayPal. The group began sending a large number of faxes to the organisations, in an attempt to deny fax services. Anonymous also fax-attacked Amazon and Tableau Software, which have withdrawn Wikileaks hosting services.