Table 2.

Privacy threats and countermeasures.

Privacy principles	Privacy threats	Countermeasures
Safe, flexible, and user-friendly privacy settings	Excessive revelation of personal health information; improper access and misuse by other users and visitors; secondary uses and disclosures of personal information; user profiling across multiple SNS.	Banning personally identifiable information; flexible and user-friendly way of setting privacy preferences; individual choice and consent; visualization of connection network; integration of privacy and security settings across multiple SNS.
Privacy by design	Secondary uses and disclosures by the SNS provider and its affiliates; secondary uses and disclosures by third parties; user profiling across multiple SNS.	Sharing de-identified data inside or outside an SNS; limiting use, disclosure, and retention; deleting user accounts upon request; a global privacy preservation model for data sharing and integration across multiple SNS.
Privacy audits	Inability to detect sources of privacy violations; user profiling across multiple SNS.	Audit trails; auditing and monitoring; transparency of data-handling practices; options for users to report privacy invasions; auditing usage and data sharing across multiple SNS.
Security for privacy	Outsider and insider attacks.	Technical barriers such as multifactor authentication, encryption, continuous monitoring, and security analytics; organizational measures such as user education and awareness, options for users to report a security incident, and breach notification and enforcement.