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Inyección SQL in Java

Crítica CWE-89 Draft — pending review
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Explicación simple

Imagine un formulario que espera un número de ticket. La inyección SQL ocurre cuando alguien escribe un comando malicioso que engaña a la base de datos para mostrar todos los datos porque nunca se validó la entrada.

Términos clave en esta página
output encoding
Converting special markup characters into safe entities so browsers display them as text rather than script.

Qué está pasando

Inyección SQL in Java occurs when unvalidated strings are concatenated into JDBC Statement or HQL/JPQL queries.

Impacto en el mundo real

In 2005, the Samy XSS worm infected over 1 million user profiles on MySpace in under 20 hours, forcing the platform offline.

Documented historical AppSec case study.

Vulnerable vs. corregido

VULNERABLE
// userId comes straight from the request
String query = "SELECT * FROM users "
    + "WHERE id = " + userId;
Statement stmt = connection.createStatement();
ResultSet rs = stmt.executeQuery(query);
FIXED
// value is bound, never concatenated
String query = "SELECT * FROM users WHERE id = ?";
PreparedStatement stmt =
    connection.prepareStatement(query);
stmt.setString(1, userId);
ResultSet rs = stmt.executeQuery();

Por qué funciona la solución

PreparedStatement precompiles the query structure in the database engine, binding parameter values separately.

Puntos críticos específicos

MyBatis: ${} vs #{}

#{} uses safe parameterized binding, while ${} performs raw string substitution.

Hibernate HQL/JPQL

Concatenating HQL queries is just as dangerous as raw SQL. Always use setParameter().

Conceptos errneos comunes

"Stored procedures prevent injection"

Only if the stored procedure itself uses parameters rather than dynamic EXECUTE strings.

Cómo comprobar si está afectado

grep -rn "createStatement().*executeQuery(.*+" --include="*.java" .
Run SpotBugs with the FindSecBugs plugin in CI to catch SQL_INJECTION_JDBC automatically.

Lista de comprobación de prevención

Preguntas frecuentes

Is Spring Data JPA safe?

Derived queries (@Query) are safe if method parameters are bound with :param or ?1.

Referencias

Ver también: Cross-Site Scripting Command InjectionPath Traversal