CWE-590 Variante Incompleto

Free of Memory not on the Heap

This vulnerability occurs when a program calls free() on a memory pointer that wasn't originally allocated using standard heap functions like malloc(), calloc(), or realloc().

Definição

What is CWE-590?

This vulnerability occurs when a program calls free() on a memory pointer that wasn't originally allocated using standard heap functions like malloc(), calloc(), or realloc().
Calling free() on an invalid pointer corrupts the program's internal memory management structures. This corruption typically leads to a crash, but it can also create opportunities for an attacker to manipulate the memory process. In some cases, an attacker can steer the free() operation to target controllable memory locations, potentially altering critical variables or even executing malicious code. Detecting these 'invalid free' issues manually is challenging, as they often involve complex pointer tracking across codebases. While SAST tools can flag the pattern, Plexicus uses AI to analyze the data flow and suggest precise code fixes, transforming a tedious security hunt into an automated remediation step and saving significant developer time.
Impacto no mundo real

Real-world CVEs caused by CWE-590

Ainda não há referências CVE públicas associadas a este CWE no catálogo da MITRE.

Como os atacantes a exploram

Trajeto do atacante passo a passo

  1. 1

    In this example, an array of record_t structs, bar, is allocated automatically on the stack as a local variable and the programmer attempts to call free() on the array. The consequences will vary based on the implementation of free(), but it will not succeed in deallocating the memory.

  2. 2

    This example shows the array allocated globally, as part of the data segment of memory and the programmer attempts to call free() on the array.

  3. 3

    Instead, if the programmer wanted to dynamically manage the memory, malloc() or calloc() should have been used.

  4. 4

    Additionally, global variables could be passed to free() when they are pointers to dynamically allocated memory.

Exemplo de código vulnerável

Vulnerable C

In this example, an array of record_t structs, bar, is allocated automatically on the stack as a local variable and the programmer attempts to call free() on the array. The consequences will vary based on the implementation of free(), but it will not succeed in deallocating the memory.

Vulnerável C 
void foo(){
  		record_t bar[MAX_SIZE];
```
/* do something interesting with bar */* 
  		
  		...
  		free(bar);}
Exemplo de código seguro

Secure C

Instead, if the programmer wanted to dynamically manage the memory, malloc() or calloc() should have been used.

Seguro C 
void foo(){
  		record_t *bar = (record_t*)malloc(MAX_SIZE*sizeof(record_t));
```
/* do something interesting with bar */* 
  		
  		...
  		free(bar);}
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-590

  • Implementation Only free pointers that you have called malloc on previously. This is the recommended solution. Keep track of which pointers point at the beginning of valid chunks and free them only once.
  • Implementation Before freeing a pointer, the programmer should make sure that the pointer was previously allocated on the heap and that the memory belongs to the programmer. Freeing an unallocated pointer will cause undefined behavior in the program.
  • Architecture and Design Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, glibc in Linux provides protection against free of invalid pointers.
  • Architecture and Design Use a language that provides abstractions for memory allocation and deallocation.
  • Testing Use a tool that dynamically detects memory management problems, such as valgrind.
Sinais de deteção

How to detect CWE-590

Fuzzing High

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.

Automated Static Analysis High

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.)

Correção automática do Plexicus

O Plexicus deteta automaticamente o CWE-590 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.

Obter uma demonstração Experimente o Plexicus gratuitamente
Perguntas frequentes

Frequently asked questions

O que é o CWE-590?

This vulnerability occurs when a program calls free() on a memory pointer that wasn't originally allocated using standard heap functions like malloc(), calloc(), or realloc().

Qual a gravidade do CWE-590?

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-590?

A MITRE não especificou as plataformas afetadas por este CWE — pode aplicar-se à maioria das stacks de aplicações.

Como posso prevenir o CWE-590?

Only free pointers that you have called malloc on previously. This is the recommended solution. Keep track of which pointers point at the beginning of valid chunks and free them only once. Before freeing a pointer, the programmer should make sure that the pointer was previously allocated on the heap and that the memory belongs to the programmer. Freeing an unallocated pointer will cause undefined behavior in the program.

Como é que o Plexicus deteta e corrige o CWE-590?

O motor SAST do Plexicus correlaciona a assinatura de fluxo de dados do CWE-590 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-590?

A MITRE publica a definição canónica em https://cwe.mitre.org/data/definitions/590.html. Pode também consultar a documentação da OWASP e do NIST para orientações adjacentes.

Fraquezas relacionadas

Weaknesses related to CWE-590

CWE-762 Pai

Mismatched Memory Management Routines

This vulnerability occurs when a program uses incompatible functions to allocate and free memory. For example, freeing memory with a…

CWE-123 Pode preceder

Write-what-where Condition

A write-what-where condition occurs when an attacker can control both the data written and the exact memory location where it's written,…

Recursos

Further reading

Pronto quando você estiver

Pare de pagar por desenvolvedor.
Comece a fechar o ciclo.

O Plexicus é o ASPM nativo de IA que verifica, filtra, corrige, pentesta e explica — de forma autónoma. Programadores ilimitados, repos ilimitados, ações de IA de utilização justa. Nível gratuito real, €269/mo anual quando estiver pronto.

Começar grátis Reservar uma demo