The 14-year-old pleaded guilty in October to attacks that occurred in 2012 at the height of Quebec's student protests.
The group for which he acted, Anonymous, was particularly vocal against the then-Liberal government, particularly a law limiting the right to protest.
A series of attacks targeting government-related websites ensued under a campaign dubbed "Operation Quebec" in response to the law, which has since been repealed.
Other people were charged in addition to the young man, whose identity is protected under youth laws.
On Wednesday, the Crown and defence recommended the probation sentence.
The Crown also said $265,904.09 was incurred in financial losses by three parties: the Montreal police, its employee credit union and the Quebec Institute of Public Health.
In some cases, there were denial-of-service attacks, rendering web pages unavailable. In other cases, home pages were altered and data seized and traded.
The boy's lawyer said the attacks weren't politically motivated and that his client wasn't old enough to grasp just how much damage his actions could cause. The accused had earlier told the court his main motivation for trading data was to obtain video games.
Youth court Judge Michele Lefebvre agreed, saying the actions were not of a criminal but of a young man who couldn't have known the extent of the consequences.
Lefebvre told the accused she thought the sentence was reasonable and is the best way of assuring he does not reoffend.
The teenager, who has no prior record, has been subject to strict rules over the past 18 months as his case wound its way through the court.
"I wish you good luck and hope not to see you here again," Lefebvre told the accused.
The sentence of 18 months includes limited access to Internet devices and 30 hours of community service, while he will be under supervision in the first six months. The boy must also enrol in a structured activity of his choosing.
He's not the first teen hacker of note from Montreal. In 2000, a teenager in western Montreal going by the alias MafiaBoy launched a series of denial-of-service attacks that crippled the websites of Yahoo Inc., EBay, CNN, Dell and Amazon.com.
That caused millions of dollars in losses and kicked off an international manhunt featuring the RCMP and the FBI.
The young man, Michael Calce, preached for Internet safety in a book he went on to co-author.
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