Russian hackers hijacked American identities and U.S. software tools and used them in an attack on Georgian government Web sites during the war between Russia and Georgia last year, according to new research to be released Monday by a nonprofit U.S. group.

In addition to refashioning common Microsoft Corp. software into a cyber-weapon, hackers collaborated on popular U.S.-based social-networking sites, including Twitter and Facebook Inc., to coordinate attacks on Georgian sites, the U.S. Cyber Consequences Unit found. While the cyberattacks on Georgia were examined shortly after the events last year, these U.S. connections weren't previously known.

The research shows how cyber-warfare has outpaced military and international agreements, which don't take into account the possibility of American resources and civilian technology being turned into weapons...