The FBI has been investigating and working to contain a malicious cyber incident on part of its computer network in recent days, according to people briefed on the matter. FBI officials believe the incident involved an FBI computer system used in investigations of images of child sexual exploitation, two sources briefed on the matter told CNN.

As Russian artillery began raining down on his homeland last month, one Ukrainian computer researcher decided to fight back the best way he knew how -- by sabotaging one of the most formidable ransomware gangs in Russia.

As Russian artillery began raining down on his homeland last month, one Ukrainian computer researcher decided to fight back the best way he knew how -- by sabotaging one of the most formidable ransomware gangs in Russia.