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-369 Base Rascunho
Divide By Zero
A divide-by-zero error occurs when software attempts to perform a division operation where the denominator is zero.
Definição
What is CWE-369?
A divide-by-zero error occurs when software attempts to perform a division operation where the denominator is zero.
This flaw typically happens when user input, external data, or an unexpected program state introduces a zero value into a calculation where it wasn't anticipated. It's especially common in functions handling physical dimensions—like size, length, or coordinates—or in mathematical routines that don't validate their inputs. Without proper checks, the division triggers a runtime error that can crash the application or create an unstable state.
Proactively preventing this requires validating all inputs and implementing safeguards before any division operation. While SAST tools can flag the dangerous pattern, Plexicus uses AI to analyze the context and suggest the specific guard clauses or error-handling code needed to fix it, turning a generic warning into an actionable fix. Managing these validation points across a large codebase is challenging; an ASPM platform like Plexicus helps track and prioritize these flaws for consistent remediation.
Impacto no mundo real
Real-world CVEs caused by CWE-369
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Invalid size value leads to divide by zero.
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"Empty" content triggers divide by zero.
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Height value of 0 triggers divide by zero.
Como os atacantes a exploram
Trajeto do atacante passo a passo
- 1
The following Java example contains a function to compute an average but does not validate that the input value used as the denominator is not zero. This will create an exception for attempting to divide by zero. If this error is not handled by Java exception handling, unexpected results can occur.
- 2
By validating the input value used as the denominator the following code will ensure that a divide by zero error will not cause unexpected results. The following Java code example will validate the input value, output an error message, and throw an exception.
- 3
The following C/C++ example contains a function that divides two numeric values without verifying that the input value used as the denominator is not zero. This will create an error for attempting to divide by zero, if this error is not caught by the error handling capabilities of the language, unexpected results can occur.
- 4
By validating the input value used as the denominator the following code will ensure that a divide by zero error will not cause unexpected results. If the method is called and a zero is passed as the second argument a DivideByZero error will be thrown and should be caught by the calling block with an output message indicating the error.
- 5
The following C# example contains a function that divides two numeric values without verifying that the input value used as the denominator is not zero. This will create an error for attempting to divide by zero, if this error is not caught by the error handling capabilities of the language, unexpected results can occur.
Exemplo de código vulnerável
Vulnerable Java
The following Java example contains a function to compute an average but does not validate that the input value used as the denominator is not zero. This will create an exception for attempting to divide by zero. If this error is not handled by Java exception handling, unexpected results can occur.
public int computeAverageResponseTime (int totalTime, int numRequests) {
return totalTime / numRequests;
} Exemplo de código seguro
Secure Java
By validating the input value used as the denominator the following code will ensure that a divide by zero error will not cause unexpected results. The following Java code example will validate the input value, output an error message, and throw an exception.
public int computeAverageResponseTime (int totalTime, int numRequests) throws ArithmeticException {
if (numRequests == 0) {
System.out.println("Division by zero attempted!");
throw ArithmeticException;
}
return totalTime / numRequests;
} 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-369
- 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-369
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.
O Plexicus deteta automaticamente o CWE-369 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-369?
Qual a gravidade do CWE-369?
Que linguagens ou plataformas são afetadas pelo CWE-369?
Como posso prevenir o CWE-369?
Como é que o Plexicus deteta e corrige o CWE-369?
Onde posso saber mais sobre o CWE-369?
Frequently asked questions
O que é o CWE-369?
A divide-by-zero error occurs when software attempts to perform a division operation where the denominator is zero.
Qual a gravidade do CWE-369?
A MITRE classifica a probabilidade de exploração como Média — a exploração é realista mas normalmente requer condições específicas.
Que linguagens ou plataformas são afetadas pelo CWE-369?
A MITRE não especificou as plataformas afetadas por este CWE — pode aplicar-se à maioria das stacks de aplicações.
Como posso prevenir o CWE-369?
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-369?
O motor SAST do Plexicus correlaciona a assinatura de fluxo de dados do CWE-369 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-369?
A MITRE publica a definição canónica em https://cwe.mitre.org/data/definitions/369.html. Pode também consultar a documentação da OWASP e do NIST para orientações adjacentes.
Fraquezas relacionadas
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Recursos
Further reading
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