CWE-570 Base Brouillon

Expression is Always False

This vulnerability occurs when code contains a conditional expression that can never evaluate to true, causing a section of the program to be permanently unreachable.

Définition

What is CWE-570?

This vulnerability occurs when code contains a conditional expression that can never evaluate to true, causing a section of the program to be permanently unreachable.
An 'always false' expression is a type of dead code that often results from logical errors, incorrect assumptions about data, or leftover debugging checks. For example, comparing a variable against a fixed value it can never hold, or checking a condition after it has already been definitively ruled out earlier in the logic. This creates a maintenance hazard, as developers might waste time debugging non-functional code, and it can mask deeper logical flaws that affect the program's real behavior. While the unreachable code itself might not directly cause a crash, it indicates flawed reasoning that could lead to security issues elsewhere. It can prevent security-critical validation routines from executing, cause resource leaks if cleanup code is skipped, or create unexpected program flow that attackers could analyze to understand the codebase. Regular code reviews and static analysis tools are effective at catching these expressions before they reach production.
Impact réel

Real-world CVEs caused by CWE-570

Aucune référence CVE publique n'est liée à ce CWE dans le catalogue MITRE pour le moment.

Comment les attaquants l'exploitent

Parcours de l'attaquant étape par étape

  1. 1

    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.

  2. 2

    However, the method never sets the isValidAccount variable after initializing it to false so the isValidProduct is mistakenly used twice. The result is that the expression "isValidProduct && isValidAccount" will always evaluate to false, so the updateAccountOrder() method will never be invoked. This will create serious problems with the product ordering application since the user account and inventory databases will be updated but the order will not be updated.

  3. 3

    This can be easily corrected by updating the appropriate variable.

  4. 4

    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.

  5. 5

    However the bit operator used to initialize the mask variable is the AND operator rather than the intended OR operator (CWE-480), this resulted in the variable mask being set to 0. As a result, the if statement will always evaluate to false and never get executed.

Exemple de code vulnérable

Vulnerable Java

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.

Vulnérable Java 
public void updateUserAccountOrder(String productNumber, String accountNumber) {
  		boolean isValidProduct = false;
  		boolean isValidAccount = false;
  		if (validProductNumber(productNumber)) {
  			isValidProduct = true;
  			updateInventory(productNumber);
  		}
  		else {
  			return;
  		}
  		if (validAccountNumber(accountNumber)) {
  			isValidProduct = true;
  			updateAccount(accountNumber, productNumber);
  		}
  		if (isValidProduct && isValidAccount) {
  			updateAccountOrder(accountNumber, productNumber);
  		}
  }
Exemple de code sécurisé

Secure Java

This can be easily corrected by updating the appropriate variable.

Sécurisé Java 
...
  if (validAccountNumber(accountNumber)) {
  	isValidAccount = true;
  	updateAccount(accountNumber, productNumber);
  }
  ...
What changed: the unsafe sink is replaced (or the input is validated/escaped) so the same payload no longer triggers the weakness.
Liste de contrôle de prévention

How to prevent CWE-570

  • Testing Use Static Analysis tools to spot such conditions.
Signaux de détection

How to detect CWE-570

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.)

Correction automatique Plexicus

Plexicus détecte automatiquement CWE-570 et ouvre une PR de correction en moins de 60 secondes.

Codex Remedium analyse chaque commit, identifie cette faiblesse précise et livre une pull request prête à être relue avec le correctif. Pas de tickets. Pas de transferts.

Obtenir une démo Essayer Plexicus gratuitement
Questions fréquentes

Frequently asked questions

Qu'est-ce que CWE-570 ?

This vulnerability occurs when code contains a conditional expression that can never evaluate to true, causing a section of the program to be permanently unreachable.

Quelle est la gravité de CWE-570 ?

MITRE n'a pas publié de note de probabilité d'exploitation pour cette faiblesse. Traitez-la comme un impact moyen jusqu'à ce que votre modèle de menace prouve le contraire.

Quels langages ou plateformes sont affectés par CWE-570 ?

MITRE n'a pas spécifié les plateformes affectées pour ce CWE — il peut s'appliquer à la plupart des stacks applicatives.

Comment puis-je prévenir CWE-570 ?

Use Static Analysis tools to spot such conditions.

Comment Plexicus détecte et corrige CWE-570 ?

Le moteur SAST de Plexicus reconnaît la signature de flux de données de CWE-570 à chaque commit. Lorsqu'une correspondance est trouvée, notre agent Codex Remedium ouvre une PR de correction avec le code corrigé, les tests et un résumé d'une ligne pour le relecteur.

Où puis-je en savoir plus sur CWE-570 ?

MITRE publie la définition canonique à https://cwe.mitre.org/data/definitions/570.html. Vous pouvez également consulter la documentation OWASP et NIST pour des conseils adjacents.

Faiblesses associées

Weaknesses related to CWE-570

CWE-710 Parent

Improper Adherence to Coding Standards

This weakness occurs when developers don't consistently follow established coding standards and best practices, which can introduce…

CWE-1041 Frère

Use of Redundant Code

This weakness occurs when a codebase contains identical or nearly identical logic duplicated across multiple functions, methods, or…

CWE-1044 Frère

Architecture with Number of Horizontal Layers Outside of Expected Range

This occurs when a software system is built with either too many or too few distinct architectural layers, falling outside a recommended…

CWE-1048 Frère

Invokable Control Element with Large Number of Outward Calls

This weakness occurs when a single function, method, or callable code block makes an excessively high number of calls to other objects or…

CWE-1059 Frère

Insufficient Technical Documentation

This weakness occurs when a software or hardware product lacks comprehensive technical documentation. Missing or incomplete details about…

CWE-1061 Frère

Insufficient Encapsulation

This weakness occurs when a software component exposes too much of its internal workings, such as data structures or implementation logic.…

CWE-1065 Frère

Runtime Resource Management Control Element in a Component Built to Run on Application Servers

This weakness occurs when an application built to run on a managed application server bypasses the server's high-level APIs and instead…

CWE-1066 Frère

Missing Serialization Control Element

This weakness occurs when a class or data structure is marked as serializable but lacks the required control methods to properly handle…

CWE-1068 Frère

Inconsistency Between Implementation and Documented Design

This weakness occurs when the actual code implementation deviates from the intended design described in its official documentation,…

Ressources

Further reading

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