CWE-570: Expression is Always False

CWE-570: Expression is Always False | RadicalNotion.AI

Code examples

Illustrative examples from MITRE showing how the weakness appears in code.

In the following Java example the updateUserAccountOrder() method used within an e-business product ordering/inventory application will validate the product number that was ordered and the user account number. If they are valid, the method will update the product inventory, the user account, and the user order appropriately.

In the following example, the hasReadWriteAccess method uses bit masks and bit operators to determine if a user has read and write privileges for a particular process. The variable mask is defined as a bit mask from the BIT_READ and BIT_WRITE constants that have been defined. The variable mask is used within the predicate of the hasReadWriteAccess method to determine if the userMask input parameter has the read and write bits set.

Vulnerable example

#define BIT_READ 0x0001 // 00000001

In the following example, the updateInventory method used within an e-business inventory application will update the inventory for a particular product. This method includes an if statement with an expression that will always evaluate to false. This is a common practice in C/C++ to introduce debugging statements quickly by simply changing the expression to evaluate to true and then removing those debugging statements by changing expression to evaluate to false. This is also a common practice for disabling features no longer needed.

Vulnerable example

int updateInventory(char* productNumber, int numberOfItems) {

Using this practice for introducing debugging statements or disabling features creates dead code that can cause problems during code maintenance and potentially introduce vulnerabilities. To avoid using expressions that evaluate to false for debugging purposes a logging API or debugging API should be used for the output of debugging messages.

CWE-570: Expression is Always False

Overview

Real-world CVEs

Common consequences

How it happens

When it is introduced

How to prevent it

How to detect it

Automated Static Analysis

Code examples

Terminology & mappings

Mapped taxonomies

Frequently asked questions

What is CWE-570?

What CVEs are caused by CWE-570?

How do you prevent CWE-570?

How is CWE-570 detected?

What are the consequences of CWE-570?

Is CWE-570 actively exploited?

References

Stay ahead of CWE-570

Overview

Real-world CVEs

Common consequences

How it happens

When it is introduced

How to prevent it

How to detect it

Automated Static Analysis

Code examples

Related weaknesses

Parent

Can precede

Terminology & mappings

Mapped taxonomies

Frequently asked questions

What is CWE-570?

What CVEs are caused by CWE-570?

How do you prevent CWE-570?

How is CWE-570 detected?

What are the consequences of CWE-570?

Is CWE-570 actively exploited?

References

Stay ahead of CWE-570