Hacktivist collective Anonymous has today claimed responsibility for cyber attacks on MI6 in the UK, and the CIA and Department of Justice in the US.
The group claimed the attack on the site of the UK spy agency MI6 today via its Twitter account @AnonCentral.
"Tango Down: http://www.mi6.gov.uk #Anonymous," stated the post.
At the time of writing the public-facing MI6 website was accessible, but MI6.gov.uk was not.
No reason was given for the attack and the group failed to respond when asked.
Earlier today the group also claimed that it was behind this morning's outages at the CIA's website, and that of the US Department of Justice. The message came from a different Twitter account, claiming to be based in Brazil.
These attacks were apparently perpetrated purely 'for the lulz [laughs]', as the Anonymous member later stated on the micro blogging site.
Being a loosely affiliated group where membership is seemingly unrestricted and unmoderated, the collective has struggled in the past to present a unified front, with internal disagreements over targets, motivations and ownership of attacks.
Earlier this month the group also attacked the Downing Street and Home Office websites. The group said the attacks were in protest against the government's "draconian" surveillance proposals, and also the UK's extradition treaty with the US.
Anonymous' preferred method of attack is Distributed Denial of Service (DDOS), where a number of computers fire a large volume of requests to a webserver over a short space of time. This uses all available bandwidth or processing power, meaning that legitimate requests to those sites are unable to be served.
The result is that the site appears offline.
Graham Cluley, senior technology consultant at security firm Sophos likens this attack to a flood of people attempting to use the same door.
"The Distributed Denial of Service (DDOS) attack isn't terribly sophisticated. It's like a whole bunch of fat guys trying to get through the same revolving doors. They bombard the website with requests until it can't cope and goes offline."
Anonymous makes a freeware tool available to its members to carry out these attacks, which it calls the Low Orbit Ion Cannon.