CWE-464Addition of Data Structure Sentinel

Description

The accidental addition of a data-structure sentinel can cause serious programming logic problems.

Data-structure sentinels are often used to mark the structure of data. A common example of this is the null character at the end of strings or a special sentinel to mark the end of a linked list. It is dangerous to allow this type of control data to be easily accessible. Therefore, it is important to protect from the addition or modification of sentinels.

Common consequences

• Integrity→Modify Application Data
  Generally this error will cause the data structure to not work properly by truncating the data.

Potential mitigations

• Implementation,Architecture and Design
  Encapsulate the user from interacting with data sentinels. Validate user input to verify that sentinels are not present.
• Implementation
  Proper error checking can reduce the risk of inadvertently introducing sentinel values into data. For example, if a parsing function fails or encounters an error, it might return a value that is the same as the sentinel.
• Architecture and Design
  Use an abstraction library to abstract away risky APIs. This is not a complete solution.
• Operation
  Use OS-level preventative functionality. This is not a complete solution.

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