CWE-90 Base Borrador

Improper Neutralization of Special Elements used in an LDAP Query ('LDAP Injection')

This vulnerability occurs when an application builds an LDAP query using untrusted user input without properly sanitizing it. An attacker can inject special characters or commands to alter the…

Definición

What is CWE-90?

This vulnerability occurs when an application builds an LDAP query using untrusted user input without properly sanitizing it. An attacker can inject special characters or commands to alter the query's logic, potentially gaining unauthorized access to, modifying, or extracting sensitive directory information.
LDAP Injection happens much like SQL injection, but targets Lightweight Directory Access Protocol queries. When user input from a form, URL parameter, or API request is directly concatenated into an LDAP search filter (like `(cn=` + userInput + `)`), an attacker can insert characters like `*`, `(`, `)`, `\`, or `null` to break the query's structure. This allows them to bypass authentication, escalate privileges, or dump the entire contents of the directory by creating filters like `*)(uid=*))(|(uid=*` that always return results. To prevent this, developers should never construct LDAP filters by simple string concatenation. Instead, use parameterized queries or the encoding functions provided by your LDAP library (like `escapeLDAPSearchFilter` in Java or `ldap_escape` in PHP) to properly neutralize special characters. Always apply the principle of least privilege to the LDAP binding account and validate all input against a strict allow-list of expected characters before it reaches the query builder.
Impacto en el mundo real

Real-world CVEs caused by CWE-90

  • CVE-2021-41232

    Chain: authentication routine in Go-based agile development product does not escape user name (CWE-116), allowing LDAP injection (CWE-90)

  • CVE-2005-2301

    Server does not properly escape LDAP queries, which allows remote attackers to cause a DoS and possibly conduct an LDAP injection attack.

Cómo lo explotan los atacantes

Ruta del atacante paso a paso

  1. 1

    Identifica una ruta de código que maneje entrada no confiable sin validación.

  2. 2

    Crea un payload que ejercite el comportamiento inseguro — inyección, traversal, overflow o abuso de lógica.

  3. 3

    Envía el payload a través de una solicitud normal y observa la reacción de la aplicación.

  4. 4

    Itera hasta que la respuesta filtre datos, ejecute código del atacante o escale privilegios.

Ejemplo de código vulnerable

Vulnerable Java

The code below constructs an LDAP query using user input address data:

Vulnerable Java 
context = new InitialDirContext(env);
  String searchFilter = "StreetAddress=" + address;
  NamingEnumeration answer = context.search(searchBase, searchFilter, searchCtls);
Ejemplo de código seguro

Secure pseudo

Seguro 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.
Lista de prevención

How to prevent CWE-90

  • 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.
Señales de detección

How to detect CWE-90

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-90 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.

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Preguntas frecuentes

Frequently asked questions

¿Qué es CWE-90?

This vulnerability occurs when an application builds an LDAP query using untrusted user input without properly sanitizing it. An attacker can inject special characters or commands to alter the query's logic, potentially gaining unauthorized access to, modifying, or extracting sensitive directory information.

¿Qué gravedad tiene CWE-90?

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-90?

MITRE lists the following affected platforms: Database Server.

¿Cómo puedo prevenir CWE-90?

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…

¿Cómo detecta y corrige Plexicus CWE-90?

El motor SAST de Plexicus detecta la firma de flujo de datos para CWE-90 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-90?

MITRE publica la definición canónica en https://cwe.mitre.org/data/definitions/90.html. También puedes consultar la documentación de OWASP y NIST para guías relacionadas.

Debilidades relacionadas

Weaknesses related to CWE-90

CWE-943 Padre

Improper Neutralization of Special Elements in Data Query Logic

This vulnerability occurs when an application builds a query for a data store (like a database) but fails to properly sanitize…

CWE-643 Hermano

Improper Neutralization of Data within XPath Expressions ('XPath Injection')

XPath Injection occurs when an application uses unvalidated user input to build an XPath query for an XML database. Without proper…

CWE-652 Hermano

Improper Neutralization of Data within XQuery Expressions ('XQuery Injection')

XQuery Injection occurs when an application uses unvalidated user input to build an XQuery expression for querying an XML database.…

CWE-89 Hermano

Improper Neutralization of Special Elements used in an SQL Command ('SQL Injection')

SQL Injection occurs when an application builds a database query using untrusted user input without properly sanitizing it. This allows an…

Recursos

Further reading

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