CWE-561 Base Brouillon

Dead Code

Dead code refers to sections of a program that can never run during normal execution, effectively making them inactive and unreachable.

Définition

What is CWE-561?

Dead code refers to sections of a program that can never run during normal execution, effectively making them inactive and unreachable.
Dead code occurs when logic within the program, such as conditional statements or function calls, permanently prevents its execution. This often results from overly restrictive conditions, code that's been commented out but left in place, or legacy functions that are no longer invoked after software updates. While not directly exploitable like a vulnerability, it bloats the codebase, obscures real issues during security reviews, and can mislead developers about the program's actual behavior. From a security and maintenance perspective, dead code creates unnecessary noise during static analysis and manual audits, potentially causing real vulnerabilities to be overlooked. It also increases the attack surface by adding complexity without providing value. Regularly removing dead code through refactoring and using code coverage tools helps keep the application lean, understandable, and easier to secure.
Impact réel

Real-world CVEs caused by CWE-561

  • CVE-2014-1266

    chain: incorrect "goto" in Apple SSL product bypasses certificate validation, allowing Adversary-in-the-Middle (AITM) attack (Apple "goto fail" bug). CWE-705 (Incorrect Control Flow Scoping) -> CWE-561 (Dead Code) -> CWE-295 (Improper Certificate Validation) -> CWE-393 (Return of Wrong Status Code) -> CWE-300 (Channel Accessible by Non-Endpoint).

Comment les attaquants l'exploitent

Parcours de l'attaquant étape par étape

  1. 1

    The condition for the second if statement is impossible to satisfy. It requires that the variables be non-null. However, on the only path where s can be assigned a non-null value, there is a return statement.

  2. 2

    In the following class, two private methods call each other, but since neither one is ever invoked from anywhere else, they are both dead code.

  3. 3

    (In this case it is a good thing that the methods are dead: invoking either one would cause an infinite loop.)

  4. 4

    The field named glue is not used in the following class. The author of the class has accidentally put quotes around the field name, transforming it into a string constant.

Exemple de code vulnérable

Vulnerable C++

The condition for the second if statement is impossible to satisfy. It requires that the variables be non-null. However, on the only path where s can be assigned a non-null value, there is a return statement.

Vulnérable C++ 
String s = null;
  if (b) {
  	s = "Yes";
  	return;
  }
  if (s != null) {
  	Dead();
  }
Exemple de code sécurisé

Secure pseudo

Sécurisé pseudo 
// Validate, sanitize, or use a safe API before reaching the sink.
function handleRequest(input) {
  const safe = validateAndEscape(input);
  return executeWithGuards(safe);
}
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-561

  • Implementation Remove dead code before deploying the application.
  • Testing Use a static analysis tool to spot dead code.
Signaux de détection

How to detect CWE-561

Architecture or Design Review High

According to SOAR [REF-1479], the following detection techniques may be useful: ``` Highly cost effective: ``` Inspection (IEEE 1028 standard) (can apply to requirements, design, source code, etc.) Formal Methods / Correct-By-Construction ``` Cost effective for partial coverage: ``` Attack Modeling

Automated Static Analysis - Binary or Bytecode High

According to SOAR [REF-1479], the following detection techniques may be useful: ``` Highly cost effective: ``` Binary / Bytecode Quality Analysis Compare binary / bytecode to application permission manifest

Dynamic Analysis with Manual Results Interpretation SOAR Partial

According to SOAR [REF-1479], the following detection techniques may be useful: ``` Cost effective for partial coverage: ``` Automated Monitored Execution

Automated Static Analysis SOAR Partial

According to SOAR [REF-1479], the following detection techniques may be useful: ``` Cost effective for partial coverage: ``` Permission Manifest Analysis

Automated Static Analysis - Source Code High

According to SOAR [REF-1479], the following detection techniques may be useful: ``` Highly cost effective: ``` Source Code Quality Analyzer ``` Cost effective for partial coverage: ``` Warning Flags Source code Weakness Analyzer Context-configured Source Code Weakness Analyzer

Dynamic Analysis with Automated Results Interpretation SOAR Partial

According to SOAR [REF-1479], the following detection techniques may be useful: ``` Cost effective for partial coverage: ``` Web Application Scanner Web Services Scanner Database Scanners

Correction automatique Plexicus

Plexicus détecte automatiquement CWE-561 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-561 ?

Dead code refers to sections of a program that can never run during normal execution, effectively making them inactive and unreachable.

Quelle est la gravité de CWE-561 ?

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-561 ?

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-561 ?

Remove dead code before deploying the application. Use a static analysis tool to spot dead code.

Comment Plexicus détecte et corrige CWE-561 ?

Le moteur SAST de Plexicus reconnaît la signature de flux de données de CWE-561 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-561 ?

MITRE publie la définition canonique à https://cwe.mitre.org/data/definitions/561.html. Vous pouvez également consulter la documentation OWASP et NIST pour des conseils adjacents.

Faiblesses associées

Weaknesses related to CWE-561

CWE-1164 Parent

Irrelevant Code

Irrelevant code refers to sections of a program that have no impact on its execution, data, or logic. Removing this code would not change…

CWE-107 Frère

Struts: Unused Validation Form

This vulnerability occurs when a Struts application contains validation form definitions that are no longer linked to any active form or…

CWE-1071 Frère

Empty Code Block

An empty code block occurs when a section of source code, such as a conditional statement or function body, contains no executable…

CWE-110 Frère

Struts: Validator Without Form Field

This vulnerability occurs when a Struts application's validation configuration file references form fields that no longer exist in the…

CWE-563 Frère

Assignment to Variable without Use

This vulnerability occurs when a value is stored in a variable, but that variable is never read or used in subsequent code, creating a…

Ressources

Further reading

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