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 Rascunho
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…
Definição
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 no mundo real
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.
Como os atacantes a exploram
Trajeto do atacante passo a passo
- 1
Identificar um caminho de código que trata input não confiável sem validação.
- 2
Criar um payload que explora o comportamento inseguro — injeção, traversal, overflow ou abuso de lógica.
- 3
Entregar o payload através de um pedido normal e observar a reação da aplicação.
- 4
Iterar até que a resposta exponha dados, execute código do atacante ou escale privilégios.
Exemplo de código vulnerável
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); Exemplo de código seguro
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.
Lista de verificação de prevenção
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.
Sinais de deteção
How to detect CWE-90
O Plexicus deteta automaticamente o CWE-90 e abre um PR de correção em menos de 60 segundos.
O Codex Remedium analisa cada commit, identifica esta fraqueza exata e entrega um pull request pronto para revisão com o patch. Sem tickets. Sem transferências.
Perguntas frequentes O que é o CWE-90?
Qual a gravidade do CWE-90?
Que linguagens ou plataformas são afetadas pelo CWE-90?
Como posso prevenir o CWE-90?
Como é que o Plexicus deteta e corrige o CWE-90?
Onde posso saber mais sobre o CWE-90?
Frequently asked questions
O que é o 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.
Qual a gravidade do CWE-90?
A MITRE não publicou uma classificação de probabilidade de exploração para esta fraqueza. Trate-a como impacto médio até o seu modelo de ameaças provar o contrário.
Que linguagens ou plataformas são afetadas pelo CWE-90?
MITRE lists the following affected platforms: Database Server.
Como posso prevenir o 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…
Como é que o Plexicus deteta e corrige o CWE-90?
O motor SAST do Plexicus correlaciona a assinatura de fluxo de dados do CWE-90 em cada commit. Quando é encontrada uma correspondência, o nosso agente Codex Remedium abre um PR de correção com o código corrigido, testes e um resumo de uma linha para o revisor.
Onde posso saber mais sobre o CWE-90?
A MITRE publica a definição canónica em https://cwe.mitre.org/data/definitions/90.html. Pode também consultar a documentação da OWASP e do NIST para orientações adjacentes.
Fraquezas relacionadas
Weaknesses related to CWE-90
CWE-943 Pai
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 Irmão
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 Irmão
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 Irmão
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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