Fuzz testing (fuzzing) is a powerful technique for generating large numbers of diverse inputs - either randomly or algorithmically - and dynamically invoking the code with those inputs. Even with random inputs, it is often capable of generating unexpected results such as crashes, memory corruption, or resource consumption. Fuzzing effectively produces repeatable test cases that clearly indicate bugs, which helps developers to diagnose the issues.
CWE-758 Clase Incompleto
Reliance on Undefined, Unspecified, or Implementation-Defined Behavior
This weakness occurs when software depends on specific behaviors of an API, data structure, or system component that are not formally guaranteed by its specification. The code assumes these…
Definición
What is CWE-758?
This weakness occurs when software depends on specific behaviors of an API, data structure, or system component that are not formally guaranteed by its specification. The code assumes these behaviors will always work a certain way, but they might change or fail under different conditions.
Relying on undefined or platform-specific behavior creates fragile code that can break unexpectedly. For example, a function might return results in a particular order on your development machine, but a different compiler or operating system version could alter that order, causing logic errors or crashes.
This often surfaces during porting to a new environment or during complex interactions between components. To avoid this, developers should strictly use documented, standardized behaviors and avoid assumptions about internal implementation details that aren't part of the official contract.
Impacto en el mundo real
Real-world CVEs caused by CWE-758
-
Change in C compiler behavior causes resultant buffer overflows in programs that depend on behaviors that were undefined in the C standard.
Cómo lo explotan los atacantes
Ruta del atacante paso a paso
- 1
This code assumes a particular function will always be found at a particular address. It assigns a pointer to that address and calls the function.
- 2
The same function may not always be found at the same memory address. This could lead to a crash, or an attacker may alter the memory at the expected address, leading to arbitrary code execution.
- 3
The following function returns a stack address.
Ejemplo de código vulnerable
Vulnerable C
This code assumes a particular function will always be found at a particular address. It assigns a pointer to that address and calls the function.
int (*pt2Function) (float, char, char)=0x08040000;
int result2 = (*pt2Function) (12, 'a', 'b');
```
// Here we can inject code to execute.* Ejemplo 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 prevención
How to prevent CWE-758
- Architecture Use safe-by-default frameworks and APIs that prevent the unsafe pattern from being expressible.
- Implementation Validate input at trust boundaries; use allowlists, not denylists.
- Implementation Apply the principle of least privilege to credentials, file paths, and runtime permissions.
- Testing Cover this weakness in CI: SAST rules + targeted unit tests for the data flow.
- Operation Monitor logs for the runtime signals listed in the next section.
Señales de detección
How to detect CWE-758
Plexicus detecta automáticamente CWE-758 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.
Preguntas frecuentes ¿Qué es CWE-758?
¿Qué gravedad tiene CWE-758?
¿Qué lenguajes o plataformas se ven afectados por CWE-758?
¿Cómo puedo prevenir CWE-758?
¿Cómo detecta y corrige Plexicus CWE-758?
¿Dónde puedo aprender más sobre CWE-758?
Frequently asked questions
¿Qué es CWE-758?
This weakness occurs when software depends on specific behaviors of an API, data structure, or system component that are not formally guaranteed by its specification. The code assumes these behaviors will always work a certain way, but they might change or fail under different conditions.
¿Qué gravedad tiene CWE-758?
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-758?
MITRE no ha especificado plataformas afectadas para esta CWE — puede aplicar a la mayoría de los stacks de aplicaciones.
¿Cómo puedo prevenir CWE-758?
Use safe-by-default frameworks, validate untrusted input at trust boundaries, and apply the principle of least privilege. Cover the data-flow signature in CI with SAST.
¿Cómo detecta y corrige Plexicus CWE-758?
El motor SAST de Plexicus detecta la firma de flujo de datos para CWE-758 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-758?
MITRE publica la definición canónica en https://cwe.mitre.org/data/definitions/758.html. También puedes consultar la documentación de OWASP y NIST para guías relacionadas.
Debilidades relacionadas
Weaknesses related to CWE-758
CWE-710 Padre
Improper Adherence to Coding Standards
This weakness occurs when developers don't consistently follow established coding standards and best practices, which can introduce…
CWE-1041 Hermano
Use of Redundant Code
This weakness occurs when a codebase contains identical or nearly identical logic duplicated across multiple functions, methods, or…
CWE-1044 Hermano
Architecture with Number of Horizontal Layers Outside of Expected Range
This occurs when a software system is built with either too many or too few distinct architectural layers, falling outside a recommended…
CWE-1048 Hermano
Invokable Control Element with Large Number of Outward Calls
This weakness occurs when a single function, method, or callable code block makes an excessively high number of calls to other objects or…
CWE-1059 Hermano
Insufficient Technical Documentation
This weakness occurs when a software or hardware product lacks comprehensive technical documentation. Missing or incomplete details about…
CWE-1061 Hermano
Insufficient Encapsulation
This weakness occurs when a software component exposes too much of its internal workings, such as data structures or implementation logic.…
CWE-1065 Hermano
Runtime Resource Management Control Element in a Component Built to Run on Application Servers
This weakness occurs when an application built to run on a managed application server bypasses the server's high-level APIs and instead…
CWE-1066 Hermano
Missing Serialization Control Element
This weakness occurs when a class or data structure is marked as serializable but lacks the required control methods to properly handle…
CWE-1068 Hermano
Inconsistency Between Implementation and Documented Design
This weakness occurs when the actual code implementation deviates from the intended design described in its official documentation,…
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