U.S. government agencies and private companies rushed to secure their computer networks following the disclosure of a sophisticated and long-running cyber-espionage intrusion suspected of being carried out by Russian hackers.
The full extent of the damage is not yet clear. But the potential threat was significant enough that the Department of Homeland Security's cybersecurity unit on Monday directed all federal agencies to remove compromised network management software and thousands of companies were expected to do the same.
What was striking about the operation was its potential scope as well as the manner in which the perpetrators managed to pierce cyber defenses and gain access to email and internal files at the Treasury and Commerce departments and potentially elsewhere.