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-823 Base Incompleto
Use of Out-of-range Pointer Offset
This vulnerability occurs when a program calculates a new memory address using a valid pointer and an offset, but the resulting address points outside the intended, safe memory region, such as…
Definição
What is CWE-823?
This vulnerability occurs when a program calculates a new memory address using a valid pointer and an offset, but the resulting address points outside the intended, safe memory region, such as beyond the bounds of an array or structure.
Pointers are designed to reference memory, but software logic typically expects them to operate within specific boundaries, like an array's allocated space. When an offset—often from user input, a miscalculation, or corrupted data—pushes the pointer beyond these boundaries, it can read or write to arbitrary, unintended memory locations.
An attacker who controls this offset can exploit this to leak sensitive data, corrupt critical program variables, crash the application, or potentially execute malicious code. The core issue is a failure to properly validate that the pointer arithmetic result remains within the legitimate range of the target data structure before it is used.
Impacto no mundo real
Real-world CVEs caused by CWE-823
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Invalid offset in undocumented opcode leads to memory corruption.
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Multimedia player uses untrusted value from a file when using file-pointer calculations.
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Spreadsheet program processes a record with an invalid size field, which is later used as an offset.
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Instant messaging library does not validate an offset value specified in a packet.
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Language interpreter does not properly handle invalid offsets in JPEG image, leading to out-of-bounds memory access and crash.
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negative offset leads to out-of-bounds read
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untrusted offset in kernel
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"blind trust" of an offset value while writing heap memory allows corruption of function pointer,leading to code execution
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 pseudo
A MITRE não publicou um exemplo de código para este CWE. O padrão abaixo é ilustrativo — consulte os Recursos para referências canónicas.
// Example pattern — see MITRE for the canonical references.
function handleRequest(input) {
// Untrusted input flows directly into the sensitive sink.
return executeUnsafe(input);
} 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-823
- 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-823
O Plexicus deteta automaticamente o CWE-823 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-823?
Qual a gravidade do CWE-823?
Que linguagens ou plataformas são afetadas pelo CWE-823?
Como posso prevenir o CWE-823?
Como é que o Plexicus deteta e corrige o CWE-823?
Onde posso saber mais sobre o CWE-823?
Frequently asked questions
O que é o CWE-823?
This vulnerability occurs when a program calculates a new memory address using a valid pointer and an offset, but the resulting address points outside the intended, safe memory region, such as beyond the bounds of an array or structure.
Qual a gravidade do CWE-823?
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-823?
A MITRE não especificou as plataformas afetadas por este CWE — pode aplicar-se à maioria das stacks de aplicações.
Como posso prevenir o CWE-823?
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-823?
O motor SAST do Plexicus correlaciona a assinatura de fluxo de dados do CWE-823 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-823?
A MITRE publica a definição canónica em https://cwe.mitre.org/data/definitions/823.html. Pode também consultar a documentação da OWASP e do NIST para orientações adjacentes.
Fraquezas relacionadas
Weaknesses related to CWE-823
CWE-119 Pai
Improper Restriction of Operations within the Bounds of a Memory Buffer
This vulnerability occurs when software accesses a memory buffer but reads from or writes to a location outside its allocated boundary.…
CWE-120 Irmão
Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
This vulnerability occurs when a program copies data from one memory location to another without first verifying that the source data will…
CWE-123 Irmão
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,…
CWE-125 Irmão
Out-of-bounds Read
An out-of-bounds read occurs when software accesses memory outside the boundaries of a buffer, array, or similar data structure, reading…
CWE-130 Irmão
Improper Handling of Length Parameter Inconsistency
This vulnerability occurs when a program reads a structured data packet or message but fails to properly validate that the declared length…
CWE-466 Irmão
Return of Pointer Value Outside of Expected Range
This vulnerability occurs when a function returns a memory pointer that points outside the expected buffer range, potentially exposing…
CWE-786 Irmão
Access of Memory Location Before Start of Buffer
This vulnerability occurs when software attempts to read from or write to a memory location positioned before the official start of a…
CWE-787 Irmão
Out-of-bounds Write
This vulnerability occurs when software incorrectly writes data outside the boundaries of its allocated memory buffer, either beyond the…
CWE-788 Irmão
Access of Memory Location After End of Buffer
This vulnerability occurs when software attempts to read from or write to a memory buffer using an index or pointer that points past the…
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