DALLAS, Oct. 14 (UPI) -- A Russian group of hackers exploited a flaw in a computer operating system to spy on NATO and other security targets, a report says.

The Dallas based cybersecurity firm that uncovered the plot, iSight Partners, said a previously undiscovered flaw in Microsoft's Windows system allowed sensitive documents pertaining to the NATO summit held in Wales in September to be targeted.

ISight dubbed the hacking group the Sandworm Team, the Washington Post reported. It was presumably working for the Russian government and has been active since at least 2009, the report said, adding that a Polish energy firm, the Ukrainian government's computers and at least one nation in Western Europe were also targeted.

The flaw, known as zero-day for the amount of time programmers are aware of it, likely allowed hackers to find e-mails, Power Point presentations and encryption keys in computers considered secure.

Although policy statements were released after the NATO summit, much of the planning occurred in secret. The agenda included preparing a unified response to Russia's influence in Crimea and Ukraine, and plans for confronting the Islamic State in Syria and Iraq.

U.S. President Barack Obama attended the meeting, as did Ukrainian President Petro Poroshenko and high-level military and civilian leaders from each NATO country.

2014 United Press International, Inc. All Rights Reserved. Any reproduction, republication, redistribution and/or modification of any UPI content is expressly prohibited without UPI's prior written consent.

See more here:

Report: Russian hackers spied on NATO