The schoolboy, from Montreal, Canada, managed to hack his way into dozens of sites including that of the Chilean government.
A court heard that he then 'bombarded them with requests to consume so much of its resources that they become unusable'.
The lad was 'working' for the hacking group Anonymous during the Quebec student uprising of 2012, where student protests about proposed tuition hikes turned into a riot.
The Mail reports that the boy's lawyers said the youngster was not 'politically motivated' but simply saw it 'as a challenge'.
The geeky tween also taught others how to penetrate high security sites.
The boy pleaded guilty to three charges of hacking government websites under the affiliation of 'hacktavist' initiative Anonymous, including accessing the Montreal police, the Quebec Institute of Public Health, the Chilean government and some non-public sites.
His attacks led to some sites being offline for up to two days, at an estimated cost of $60,000.
The boy will be sentenced next month.