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.)
CWE-90 Base Brouillon
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…
Définition
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.
Impact réel
Real-world CVEs caused by CWE-90
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Chain: authentication routine in Go-based agile development product does not escape user name (CWE-116), allowing LDAP injection (CWE-90)
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Server does not properly escape LDAP queries, which allows remote attackers to cause a DoS and possibly conduct an LDAP injection attack.
Comment les attaquants l'exploitent
Parcours de l'attaquant étape par étape
- 1
Identifier un chemin de code qui traite des entrées non fiables sans validation.
- 2
Élaborer une charge utile qui exploite le comportement non sécurisé — injection, traversal, débordement ou abus de logique.
- 3
Délivrer la charge utile via une requête normale et observer la réaction de l'application.
- 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 Java
The code below constructs an LDAP query using user input address data:
context = new InitialDirContext(env);
String searchFilter = "StreetAddress=" + address;
NamingEnumeration answer = context.search(searchBase, searchFilter, searchCtls); Exemple de code sécurisé
Secure 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-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.
Signaux de détection
How to detect CWE-90
CWE-90
Don't catalog this weakness. Prove it's reachable.
Plexicus turns CWE catalogs into evidence: every CWE-pattern is matched against your real code graph, reach is proven on a sandbox clone, and verified findings ship as reviewed PRs.
Questions fréquentes Qu'est-ce que CWE-90 ?
Quelle est la gravité de CWE-90 ?
Quels langages ou plateformes sont affectés par CWE-90 ?
Comment puis-je prévenir CWE-90 ?
Comment Plexicus détecte et corrige CWE-90 ?
Où puis-je en savoir plus sur CWE-90 ?
Frequently asked questions
Qu'est-ce que 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.
Quelle est la gravité de CWE-90 ?
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-90 ?
MITRE lists the following affected platforms: Database Server.
Comment puis-je prévenir 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…
Comment Plexicus détecte et corrige CWE-90 ?
Le moteur SAST de Plexicus reconnaît la signature de flux de données de CWE-90 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-90 ?
MITRE publie la définition canonique à https://cwe.mitre.org/data/definitions/90.html. Vous pouvez également consulter la documentation OWASP et NIST pour des conseils adjacents.
Faiblesses associées
Weaknesses related to CWE-90
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-643 Frère
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 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…
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