COMMON WEAKNESS ENUMERATIONDraft

CWE-484

Omitted Break Statement in Switch

The product omits a break statement within a switch or similar construct, causing code associated with multiple conditions to execute. This can cause problems when the programmer only intended to execute code associated with one condition.

Abstraction

Base

Structure

Simple

Likelihood of Exploit

Medium

Understand the problem

What is the problem?

The product omits a break statement within a switch or similar construct, causing code associated with multiple conditions to execute. This can cause problems when the programmer only intended to execute code associated with one condition.

Extended description

This can lead to critical code executing in situations where it should not.

Root cause

How and when does the problem arise?

Lifecycle phase

Implementation

Risk

What does successful exploitation lead to?

Alter Execution Logic

Affected security scopes: Other

This weakness can cause unintended logic to be executed and other unexpected application behavior.

Defence

How is it prevented and fixed?

Implementation

Implementation-phase defence

Detail
Omitting a break statement so that one may fall through is often indistinguishable from an error, and therefore should be avoided. If you need to use fall-through capabilities, make sure that you have clearly documented this within the switch statement, and ensure that you have examined all the logical possibilities.

Implementation

Implementation-phase defence

Detail
The functionality of omitting a break statement could be clarified with an if statement. This method is much safer.

Verification

How is it detected?

White Box

Omission of a break statement might be intentional, in order to support fallthrough. Automated detection methods might therefore be erroneous. Semantic understanding of expected product behavior is required to interpret whether the code is correct.

Black Box

Since this weakness is associated with a code construct, it would be indistinguishable from other errors that produce the same behavior.

Automated Static Analysis

High
Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)