CWE-464: Addition of Data Structure Sentinel

How it's found

Addition of Data Structure Sentinel is typically found by tracing untrusted input from where it enters the system to the point where it is used without the check or neutralization this weakness describes, combining manual code review with dynamic testing.

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.

Consequences

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

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.

Where this fits in a TurboPentest engagement

This weakness is not covered by the automated black-box pentest. IntegSec pentesters cover it in a manual engagement.

Frequently asked questions

Related CWEs

• Class weakness
  CWE-138: Improper Neutralization of Special Elements