Failure to account for default case in switch
From OWASP
This is a Vulnerability. To view all vulnerabilities, please see the Vulnerability Category page.
Last revision (mm/dd/yy): 2/21/2009
Vulnerabilities Table of Contents
Description
The failure to account for the default case in switch statements may lead to complex logical errors and may aid in other, unexpected security-related conditions.
Consequences
Undefined: Depending on the logical circumstances involved, any consequences may result: e.g., issues of confidentiality, authentication, authorization, availability, integrity, accountability, or non-repudiation.
Exposure period
Implementation: This flaw is a simple logic issue, introduced entirely at implementation time.
Platform
- Language: Any
- Platform: Any
Required resources
Any
Severity
Undefined.
Likelihood of exploit
Undefined.
This flaw represents a common problem in software development, in which not all possible values for a variable are considered or handled by a given process. Because of this, further decisions are made based on poor information, and cascading failure results.
This cascading failure may result in any number of security issues, and constitutes a significant failure in the system. In the case of switch style statements, the very simple act of creating a default case can mitigate this situation, if done correctly.
Often however, the default cause is used simply to represent an assumed option, as opposed to working as a sanity check. This is poor practice and in some cases is as bad as omitting a default case entirely.
Risk Factors
TBD
Examples
In general, a safe switch statement has this form:
switch (value) {
case 'A':
printf("A!\n");
break;
case 'B':
printf("B!\n");
break;
default:
printf("Neither A nor B\n");
}
This is because the assumption cannot be made that all possible cases are accounted for. A good practice is to reserve the default case for error handling.
Related Attacks
Related Vulnerabilities
- Undefined: A logical flaw of this kind might lead to any number of other flaws.
Related Controls
- Implementation: Ensure that there are no unaccounted for cases, when adjusting flow or values based on the value of a given variable. In switch statements, this can be accomplished through the use of the default label.
Related Technical Impacts
References
TBD
