The use of social networking sites introduces the risk of:

Social networking platforms make it easy for users to post details about their work, projects, clients, or internal processes, which can expose trade secrets or sensitive business information to competitors and attackers. This disclosure risk is one of the primary security concerns organizations face when employees use social media, and it can violate confidentiality policies or regulatory requirements.

Data classification is an internal administrative process and is not directly threatened by employees simply using social networking sites.

Data availability issues relate to systems being accessible or not, which is not a primary risk introduced by social media use.

Chain of custody is a forensic and legal concept related to evidence handling, not a risk introduced by social networking.