COMMON WEAKNESS ENUMERATIONIncomplete

CWE-464

Addition of Data Structure Sentinel

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

Abstraction

Base

Structure

Simple

Likelihood of Exploit

High

Understand the problem

What is the problem?

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

Extended description

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.

Root cause

How and when does the problem arise?

Lifecycle phase

Implementation

Risk

What does successful exploitation lead to?

Modify Application Data

Affected security scopes: Integrity

Generally this error will cause the data structure to not work properly by truncating the data.

Defence

How is it prevented and fixed?

Implementation · Architecture and Design

Defence to apply across several lifecycle phases

Detail
Encapsulate the user from interacting with data sentinels. Validate user input to verify that sentinels are not present.

Implementation

Implementation-phase defence

Detail
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

Architecture and design approach

Detail
Use an abstraction library to abstract away risky APIs. This is not a complete solution.

Operation

Operational defence

Detail
Use OS-level preventative functionality. This is not a complete solution.