CWE-1289 Base Incomplet

Improper Validation of Unsafe Equivalence in Input

This vulnerability occurs when an application accepts user input as a reference (like a file path or resource identifier) but fails to properly check if that input is functionally equivalent to a…

Définition

What is CWE-1289?

This vulnerability occurs when an application accepts user input as a reference (like a file path or resource identifier) but fails to properly check if that input is functionally equivalent to a dangerous or restricted value.
Attackers can bypass security checks by crafting inputs that look safe to the validation layer but are processed as dangerous by a downstream system. For instance, a filter might block the exact string `` using a case-sensitive match, but a browser interprets HTML tags case-insensitively, so an input like `` would bypass the filter and still execute. This happens because validation logic often makes assumptions about how data will be interpreted later in the processing chain. To prevent this, security checks must validate inputs based on the same parsing rules used by the ultimate consumer of that data, such as the operating system, database, or web browser.
Impact réel

Real-world CVEs caused by CWE-1289

  • CVE-2021-39155

    Chain: A microservice integration and management platform compares the hostname in the HTTP Host header in a case-sensitive way (CWE-178, CWE-1289), allowing bypass of the authorization policy (CWE-863) using a hostname with mixed case or other variations.

  • CVE-2020-11053

    Chain: Go-based Oauth2 reverse proxy can send the authenticated user to another site at the end of the authentication flow. A redirect URL with HTML-encoded whitespace characters can bypass the validation (CWE-1289) to redirect to a malicious site (CWE-601)

  • CVE-2005-0269

    File extension check in forum software only verifies extensions that contain all lowercase letters, which allows remote attackers to upload arbitrary files via file extensions that include uppercase letters.

  • CVE-2001-1238

    Task Manager does not allow local users to end processes with uppercase letters named (1) winlogon.exe, (2) csrss.exe, (3) smss.exe and (4) services.exe via the Process tab which could allow local users to install Trojan horses that cannot be stopped.

  • CVE-2004-2214

    HTTP server allows bypass of access restrictions using URIs with mixed case.

Comment les attaquants l'exploitent

Parcours de l'attaquant étape par étape

  1. 1

    Identifier un chemin de code qui traite des entrées non fiables sans validation.

  2. 2

    Élaborer une charge utile qui exploite le comportement non sécurisé — injection, traversal, débordement ou abus de logique.

  3. 3

    Délivrer la charge utile via une requête normale et observer la réaction de l'application.

  4. 4

    Itérer jusqu'à ce que la réponse divulgue des données, exécute le code de l'attaquant ou élève les privilèges.

Exemple de code vulnérable

Vulnerable pseudo

MITRE n'a pas publié d'exemple de code pour ce CWE. Le motif ci-dessous est illustratif — voir Ressources pour les références canoniques.

Vulnérable pseudo 
// Example pattern — see MITRE for the canonical references.
function handleRequest(input) {
  // Untrusted input flows directly into the sensitive sink.
  return executeUnsafe(input);
}
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-1289

  • Implementation Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does. When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue." Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
Signaux de détection

How to detect CWE-1289

SAST High

Exécuter une analyse statique (SAST) sur le code source à la recherche du motif non sécurisé dans le flux de données.

DAST Moderate

Exécuter des tests de sécurité applicative dynamique (DAST) contre le point de terminaison en ligne.

Runtime Moderate

Surveiller les journaux runtime pour détecter des traces d'exception inhabituelles, des entrées malformées ou des tentatives de contournement d'autorisation.

Code review Moderate

Revue de code : signaler tout nouveau code qui traite les entrées de cette surface sans utiliser les helpers du framework validés.

Correction automatique Plexicus

Plexicus détecte automatiquement CWE-1289 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-1289 ?

This vulnerability occurs when an application accepts user input as a reference (like a file path or resource identifier) but fails to properly check if that input is functionally equivalent to a dangerous or restricted value.

Quelle est la gravité de CWE-1289 ?

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-1289 ?

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-1289 ?

Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does. When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and…

Comment Plexicus détecte et corrige CWE-1289 ?

Le moteur SAST de Plexicus reconnaît la signature de flux de données de CWE-1289 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-1289 ?

MITRE publie la définition canonique à https://cwe.mitre.org/data/definitions/1289.html. Vous pouvez également consulter la documentation OWASP et NIST pour des conseils adjacents.

Faiblesses associées

Weaknesses related to CWE-1289

CWE-20 Parent

Improper Input Validation

This vulnerability occurs when an application accepts data from an external source but fails to properly verify that the data is safe and…

CWE-102 Frère

Struts: Duplicate Validation Forms

This vulnerability occurs when an application defines multiple Struts validation forms with identical names. The framework then…

CWE-103 Frère

Struts: Incomplete validate() Method Definition

This vulnerability occurs in a Struts application when a validator form either completely omits a validate() method or includes one but…

CWE-104 Frère

Struts: Form Bean Does Not Extend Validation Class

This vulnerability occurs in Apache Struts applications when a form bean class does not properly extend the framework's validation class.…

CWE-105 Frère

Struts: Form Field Without Validator

This vulnerability occurs when a Struts application form contains an input field that lacks a corresponding validator, leaving it open to…

CWE-106 Frère

Struts: Plug-in Framework not in Use

This weakness occurs when a Java application, particularly one using the Struts framework, does not implement a structured input…

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-108 Frère

Struts: Unvalidated Action Form

In Apache Struts, every Action Form that processes user input must have a corresponding validation form configured. Missing this…

CWE-109 Frère

Struts: Validator Turned Off

This vulnerability occurs when an application built with Apache Struts intentionally disables its built-in validation framework. By…

Ressources

Further reading

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