CWE-597 Variante Brouillon

Use of Wrong Operator in String Comparison

This vulnerability occurs when a developer incorrectly compares string values, typically by using reference equality operators (like == or !=) instead of dedicated string comparison methods (like…

Définition

What is CWE-597?

This vulnerability occurs when a developer incorrectly compares string values, typically by using reference equality operators (like == or !=) instead of dedicated string comparison methods (like .equals()).

In languages like Java, using '==' to compare strings checks if two object references point to the same memory location, not whether their textual content is identical. This is a common logic error because two separate string objects with the same characters will fail an '==' test, leading to unexpected program behavior and flawed conditional logic. While this often results in general bugs or incorrect functionality, it becomes a security issue when the flawed comparison is part of an authentication check, authorization decision, or input validation. An attacker could potentially bypass security controls by exploiting the unintended mismatch, turning a simple coding mistake into a system vulnerability.

Impact réel

Real-world CVEs caused by CWE-597

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
In the example below, two Java String objects are declared and initialized with the same string values. An if statement is used to determine if the strings are equivalent.
2
However, the if statement will not be executed as the strings are compared using the "==" operator. For Java objects, such as String objects, the "==" operator compares object references, not object values. While the two String objects above contain the same string values, they refer to different object references, so the System.out.println statement will not be executed. To compare object values, the previous code could be modified to use the equals method:
3
In the example below, three JavaScript variables are declared and initialized with the same values. Note that JavaScript will change a value between numeric and string as needed, which is the reason an integer is included with the strings. An if statement is used to determine whether the values are the same.
4
However, the body of the if statement will not be executed, as the "===" compares both the type of the variable AND the value. As the types of the first comparison are number and string, it fails. The types in the second are int and reference, so this one fails as well. The types in the third are reference and string, so it also fails. While the variables above contain the same values, they are contained in different types, so the document.getElementById... statement will not be executed in any of the cases. To compare object values, the previous code is modified and shown below to use the "==" for value comparison so the comparison in this example executes the HTML statement:
5
In the example below, two PHP variables are declared and initialized with the same numbers - one as a string, the other as an integer. Note that PHP will change the string value to a number for a comparison. An if statement is used to determine whether the values are the same.

Exemple de code vulnérable

Vulnerable Java

In the example below, two Java String objects are declared and initialized with the same string values. An if statement is used to determine if the strings are equivalent.

Vulnérable Java

String str1 = new String("Hello");
  String str2 = new String("Hello");
  if (str1 == str2) {
  	System.out.println("str1 == str2");
  }

Exemple de code sécurisé

Secure Java

However, the if statement will not be executed as the strings are compared using the "==" operator. For Java objects, such as String objects, the "==" operator compares object references, not object values. While the two String objects above contain the same string values, they refer to different object references, so the System.out.println statement will not be executed. To compare object values, the previous code could be modified to use the equals method:

Sécurisé Java

if (str1.equals(str2)) {
  	System.out.println("str1 equals str2");
  }

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-597

Implementation Within Java, use .equals() to compare string values. Within JavaScript, use == to compare string values. Within PHP, use == to compare a numeric value to a string value. (PHP converts the string to a number.)

Signaux de détection

How to detect CWE-597

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-597 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-597 ?

Quelle est la gravité de CWE-597 ?

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-597 ?

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-597 ?

Within Java, use .equals() to compare string values. Within JavaScript, use == to compare string values. Within PHP, use == to compare a numeric value to a string value. (PHP converts the string to a number.)

Comment Plexicus détecte et corrige CWE-597 ?

Le moteur SAST de Plexicus reconnaît la signature de flux de données de CWE-597 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-597 ?

MITRE publie la définition canonique à https://cwe.mitre.org/data/definitions/597.html. Vous pouvez également consulter la documentation OWASP et NIST pour des conseils adjacents.

Faiblesses associées

Weaknesses related to CWE-597

CWE-595 Parent

Comparison of Object References Instead of Object Contents

This vulnerability occurs when code incorrectly checks if two object references point to the same memory location, rather than comparing…

CWE-1097 Frère

Persistent Storable Data Element without Associated Comparison Control Element

This weakness occurs when a persistent data object lacks the necessary methods to be properly compared, which can lead to inconsistent or…

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