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 Classe 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…
Definição
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 no 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.
Como os atacantes a exploram
Trajeto do atacante passo a passo
- 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.
Exemplo de código vulnerável
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.* 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-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.
Sinais de deteção
How to detect CWE-758
CWE-758
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.
Perguntas frequentes O que é o CWE-758?
Qual a gravidade do CWE-758?
Que linguagens ou plataformas são afetadas pelo CWE-758?
Como posso prevenir o CWE-758?
Como é que o Plexicus deteta e corrige o CWE-758?
Onde posso saber mais sobre o CWE-758?
Frequently asked questions
O que é o 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.
Qual a gravidade do CWE-758?
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-758?
A MITRE não especificou as plataformas afetadas por este CWE — pode aplicar-se à maioria das stacks de aplicações.
Como posso prevenir o 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.
Como é que o Plexicus deteta e corrige o CWE-758?
O motor SAST do Plexicus correlaciona a assinatura de fluxo de dados do CWE-758 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-758?
A MITRE publica a definição canónica em https://cwe.mitre.org/data/definitions/758.html. Pode também consultar a documentação da OWASP e do NIST para orientações adjacentes.
Fraquezas relacionadas
Weaknesses related to CWE-758
CWE-710 Pai
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 Irmão
Use of Redundant Code
This weakness occurs when a codebase contains identical or nearly identical logic duplicated across multiple functions, methods, or…
CWE-1044 Irmão
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 Irmão
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 Irmão
Insufficient Technical Documentation
This weakness occurs when a software or hardware product lacks comprehensive technical documentation. Missing or incomplete details about…
CWE-1061 Irmão
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 Irmão
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 Irmão
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 Irmão
Inconsistency Between Implementation and Documented Design
This weakness occurs when the actual code implementation deviates from the intended design described in its official documentation,…
Pronto para validar o que importa?
Pronto para validar o que importa.
O Plexicus é Proof-Driven AppSec: achados validados, compreensão contextual e remediação revisada — ancorada em evidência, escopada com você.