While many apps collect vast troves of user data, sometimes without explicit consent, experts say Chinese e-commerce giant Pinduoduo has taken violations of privacy and data security to the next level.

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.