Four hackers have been charged with breaching the computer networks of major technology companies and the US Army, and stealing more than $100 million in intellectual property, the US Department of Justice revealed yesterday.

According to court records, from January 2011 to March 2014, the four men allegedly hacked into the computer networks of Microsoft, Epic Games, Valve Corporation, Zombie Studios, and the US Army, stealing unreleased software, software source code, trade secrets, copyrighted and pre-release works, and other confidential and proprietary information. 

The alleged cyber theft included software and data related to Microsoft's Xbox One gaming console and Xbox Live online gaming system, pre-release copies of popular video games such as Call of Duty: Modern Warfare 3 and Gears of War 3, as well as Apache helicopter training software. The DoJ claimed the technology was worth between $100 million and $200 million.

Part of the group called Xbox Underground, the four allegedly used SQL injection attacks and stolen usernames and passwords of company employees and their software development partners to break into the targeted companies' networks.

Nathan Leroux, 20, of Bowie, Maryland; Sanadodeh Nesheiwat, 28, of Washington, New Jersey; David Pokora, 22, of Mississauga, Ontario, Canada; and Austin Alcala, 18, of McCordsville, Indiana, were charged on 18 counts by a federal grand jury in the District of Delaware on April 23, 2014.

The charges include conspiracies to commit computer fraud, copyright infringement, wire fraud, mail fraud, identity theft, and theft of trade secrets, as well as individual counts of aggravated identity theft, unauthorized computer access, copyright infringement, and wire fraud.

Pokora and Nesheiwat have already pleaded guilty to conspiracy to commit computer fraud and copyright infringement, and are scheduled for sentencing in January. Both face up to five years in prison.

"These were extremely sophisticated hackers ... Don't be fooled by their ages", said assistant US attorney Ed McAndrew after a court hearing yesterday.