CWE-643 Base Incomplet High likelihood

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 sanitization, attackers can manipulate the query's structure.

Définition

What is CWE-643?

XPath Injection occurs when an application uses unvalidated user input to build an XPath query for an XML database. Without proper sanitization, attackers can manipulate the query's structure.
This vulnerability allows an attacker to alter the intended logic of the XPath expression. By injecting special characters or control sequences, they can change which data is retrieved from the XML source, potentially bypassing application logic, authentication, or access controls. Successful exploitation can lead to unauthorized data exposure, information disclosure, or manipulation of application flow. Developers must treat all user input used in XPath queries as untrusted and implement proper validation or parameterization to prevent these attacks.
Impact réel

Real-world CVEs caused by CWE-643

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. 1

    Consider the following simple XML document that stores authentication information and a snippet of Java code that uses XPath query to retrieve authentication information:

  2. 2

    The Java code used to retrieve the home directory based on the provided credentials is:

  3. 3

    Assume that user "john" wishes to leverage XPath Injection and login without a valid password. By providing a username "john" and password "' or ''='" the XPath expression now becomes

  4. 4

    This lets user "john" login without a valid password, thus bypassing authentication.

Exemple de code vulnérable

Vulnerable Java

The Java code used to retrieve the home directory based on the provided credentials is:

Vulnérable Java 
XPath xpath = XPathFactory.newInstance().newXPath();
  XPathExpression xlogin = xpath.compile("//users/user[login/text()='" + login.getUserName() + "' and password/text() = '" + login.getPassword() + "']/home_dir/text()");
  Document d = DocumentBuilderFactory.newInstance().newDocumentBuilder().parse(new File("db.xml"));
  String homedir = xlogin.evaluate(d);
Charge utile de l'attaquant

Assume that user "john" wishes to leverage XPath Injection and login without a valid password. By providing a username "john" and password "' or ''='" the XPath expression now becomes

Charge utile de l'attaquant 
//users/user[login/text()='john' or ''='' and password/text() = '' or ''='']/home_dir/text()
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-643

  • Implementation Use parameterized XPath queries (e.g. using XQuery). This will help ensure separation between data plane and control plane.
  • Implementation Properly validate user input. Reject data where appropriate, filter where appropriate and escape where appropriate. Make sure input that will be used in XPath queries is safe in that context.
Signaux de détection

How to detect CWE-643

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-643 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-643 ?

XPath Injection occurs when an application uses unvalidated user input to build an XPath query for an XML database. Without proper sanitization, attackers can manipulate the query's structure.

Quelle est la gravité de CWE-643 ?

MITRE évalue la probabilité d'exploitation comme Élevée — cette faiblesse est activement exploitée et doit être priorisée pour la remédiation.

Quels langages ou plateformes sont affectés par CWE-643 ?

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-643 ?

Use parameterized XPath queries (e.g. using XQuery). This will help ensure separation between data plane and control plane. Properly validate user input. Reject data where appropriate, filter where appropriate and escape where appropriate. Make sure input that will be used in XPath queries is safe in that context.

Comment Plexicus détecte et corrige CWE-643 ?

Le moteur SAST de Plexicus reconnaît la signature de flux de données de CWE-643 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-643 ?

MITRE publie la définition canonique à https://cwe.mitre.org/data/definitions/643.html. Vous pouvez également consulter la documentation OWASP et NIST pour des conseils adjacents.

Faiblesses associées

Weaknesses related to CWE-643

CWE-943 Parent

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-652 Frère

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 Frère

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…

CWE-90 Frère

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…

Ressources

Further reading

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