CWE-359: Exposure of Private Personal Information to an Unauthorized Actor

There are many types of sensitive information that products must protect from attackers, including system data, communications, configuration, business secrets, intellectual property, and an individual's personal (private) information. Private personal information may include a password, phone number, geographic location, personal messages, credit card number, etc. Private information is important to consider whether the person is a user of the product, or part of a data set that is processed by the product. An exposure of private information does not necessarily prevent the product from working properly, and in fact the exposure might be intended by the developer, e.g. as part of data sharing with other organizations. However, the exposure of personal private information can still be undesirable or explicitly prohibited by law or regulation.

Some types of private information include:

• Government identifiers, such as Social Security Numbers
• Contact information, such as home addresses and telephone numbers
• Geographic location - where the user is (or was)
• Employment history
• Financial data - such as credit card numbers, salary, bank accounts, and debts
• Pictures, video, or audio
• Behavioral patterns - such as web surfing history, when certain activities are performed, etc.
• Relationships (and types of relationships) with others - family, friends, contacts, etc.
• Communications - e-mail addresses, private messages, text messages, chat logs, etc.
• Health - medical conditions, insurance status, prescription records
• Account passwords and other credentials

Some of this information may be characterized as PII (Personally Identifiable Information), Protected Health Information (PHI), etc. Categories of private information may overlap or vary based on the intended usage or the policies and practices of a particular industry.

Sometimes data that is not labeled as private can have a privacy implication in a different context. For example, student identification numbers are usually not considered private because there is no explicit and publicly-available mapping to an individual student's personal information. However, if a school generates identification numbers based on student social security numbers, then the identification numbers should be considered private.