The findings were first reported by ABC News.
Overall, 15 percent of the world's Internet traffic was "hijacked" by Chinese telecom companies, according to the report. The cyber attack was previously reported on, but the commission details the extent to which U.S. government and military sites were affected.
"This incident affected traffic to and from U.S. government (''.gov'') and military (''.mil'') sites, including those for the Senate, the army, the navy, the marine corps, the air force, the office of secretary of Defense, the National Aeronautics and Space Administration, the Department of Commerce, the National Oceanic and Atmospheric Administration, and many others. Certain commercial websites were also affected, such as those for Dell, Yahoo!, Microsoft, and IBM," the report states.
No motive for the alleged attack was given, but the report highlighted "a number of serious implications" for cyber security.
"This level of access could enable surveillance of specific users or sites. It could disrupt a data transaction and prevent a user from establishing a connection with a site. It could even allow a diversion of data to somewhere that the user did not intend."
Back in April, CBS News correspondent Terry McCarthy reported on the, with government and private networks under near constant threat, particularly from China and Russia.
The Pentagon alone gets 360 million unauthorized probes a day and corporate America is losing critical data to overseas competitors, robbing the U.S. economy of up to $20 billion a year.
"It's so widespread now that we face the prospect of entire industries being stolen," said Scott Borg of the U.S. Cyber Consequences Unit told CBS News back in April.
In one example, McCarthy reported that there are factories in China and Southeast Asia that are exact replicas of plants in the United States - built with everything from hacked blueprints and supplier lists down to the settings used to regulate valve pressure for individual machines.