John Brennan
Pictured: Former CIA director John BrennanReuters

A British teenager has admitted conducting cyberattacks against the computers of high-level US government targets, including officials from the CIA and FBI.

Kane Gamble, 18, of Linford Crescent in Coalville, appeared in Leicester Crown Court on Friday (6 October) and pleaded guilty to eight charges of "performing a function with intent to secure unauthorised access" and two of "unauthorised modification of computer material."

Targets included former Central Intelligence Agency director John Brennan and former deputy director of the Federal Bureau of Investigation Mark Giuliano.

According to the Leicester Mercury, other hacking victims included Homeland Security chief Jeh Johnson, ex-National Geospatial Intelligence Agency executive Vonna Heaton and Barack Obama's former science and technology adviser John Holdren.

Reports indicate that Gamble committed his hacks between June 2015 and February 2016.

He allegedly set his sights on an FBI portal in November 2015 and three months later moved on to accounts of the former US intelligence director James Clapper.

He also attacked the networks of the US Department of Justice (DoJ). Gamble was released on conditional bail and is set for sentencing on 15 December.

Local media reported that Gamble's barrister said his client was "on the autistic spectrum" and launched the hacks when he was as young as 15-years-old.

A hacking group known as "Crackas with Attitude" previously told technology website Motherboard that it was responsible for hacking both Clapper and Brennan.

In January 2016, matching up with the timescale of the dates released by the court, one of the alleged culprits claimed to have changed the setting on Clapper's phone line so that incoming calls to his home number would instead be forwarded to the Free Palestine Movement.

Motherboard reported at the time one of the stolen phone numbers seemingly belonged to Vonna Heaton. When called, Heaton declined to answer the journalist's questions.

The "Crackas with Attitude" group, known to be of teenage age, reportedly consisted of six members. It remains unclear if Gamble was affiliated with the cyber gang.

The defendant was arrested in February 2016 but was not publicly named until now due to his age. The judge in the case said that "all sentencing options remain open," the Mercury reported.

On 8 September last year, the DoJ announced that two US men - Andrew Otto Boggs and Justin Gray Liverman - had been arrested for allegedly playing a role in the hacks on government officials.

"At least three other members of the conspiracy are located in the United Kingdom and are being investigated by the Crown Prosecution Service," it said in a release at the time.