CWE-597 Variante Borrador

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…

Definición

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.
Impacto en el mundo real

Real-world CVEs caused by CWE-597

Todavía no hay CVEs públicos enlazados a esta CWE en el catálogo de MITRE.

Cómo lo explotan los atacantes

Ruta del atacante paso a paso

  1. 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. 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. 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. 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. 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.

Ejemplo de código vulnerable

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.

Vulnerable Java 
String str1 = new String("Hello");
  String str2 = new String("Hello");
  if (str1 == str2) {
  	System.out.println("str1 == str2");
  }
Ejemplo de código seguro

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:

Seguro 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.
Lista de prevención

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.)
Señales de detección

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.)

Auto-corrección de Plexicus

Plexicus detecta automáticamente CWE-597 y abre un PR de corrección en menos de 60 segundos.

Codex Remedium escanea cada commit, identifica esta debilidad concreta y entrega un pull request listo para revisión con el parche. Sin tickets. Sin traspasos.

Solicitar demo Probar Plexicus gratis
Preguntas frecuentes

Frequently asked questions

¿Qué es 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()).

¿Qué gravedad tiene CWE-597?

MITRE no ha publicado una calificación de probabilidad de explotación para esta debilidad. Trátala como de impacto medio hasta que tu modelo de amenazas demuestre lo contrario.

¿Qué lenguajes o plataformas se ven afectados por CWE-597?

MITRE no ha especificado plataformas afectadas para esta CWE — puede aplicar a la mayoría de los stacks de aplicaciones.

¿Cómo puedo prevenir 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.)

¿Cómo detecta y corrige Plexicus CWE-597?

El motor SAST de Plexicus detecta la firma de flujo de datos para CWE-597 en cada commit. Cuando hay coincidencia, nuestro agente Codex Remedium abre un PR de corrección con el código corregido, las pruebas y un resumen de una línea para el revisor.

¿Dónde puedo aprender más sobre CWE-597?

MITRE publica la definición canónica en https://cwe.mitre.org/data/definitions/597.html. También puedes consultar la documentación de OWASP y NIST para guías relacionadas.

Debilidades relacionadas

Weaknesses related to CWE-597

CWE-595 Padre

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 Hermano

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…

Recursos

Further reading

Listo cuando tú lo estés

Deja de pagar por desarrollador.
Empieza a cerrar el bucle.

Plexicus es el ASPM nativo de IA que escanea, filtra, corrige, pentestea y explica — de forma autónoma. Desarrolladores ilimitados, repos ilimitados, acciones de IA de uso justo. Nivel gratuito real, €269/mo anual cuando estés listo.

Comenzar gratis Reservar una demo