CWE-1284 Base Incompleto

Improper Validation of Specified Quantity in Input

This vulnerability occurs when an application accepts user input meant to define a quantity—like a number, size, or count—but fails to properly check if that value is safe and reasonable before…

Definição

What is CWE-1284?

This vulnerability occurs when an application accepts user input meant to define a quantity—like a number, size, or count—but fails to properly check if that value is safe and reasonable before using it.
Applications constantly handle user-defined quantities: file sizes to upload, lengths for arrays, loop iteration counts, or prices for transactions. If your code trusts these numbers without scrutiny, it can be tricked into performing dangerous actions. Attackers exploit this by submitting extreme or malicious values—like a negative number, an impossibly large size, or zero—to manipulate the program's logic, crash it, or force it into an unstable state. Failing to validate quantities has direct consequences. Your application might allocate all available memory based on a huge size, perform a calculation that leads to an integer overflow, or enter an infinite loop. This opens the door to denial-of-service, buffer overflows, or logic flaws that compromise security. Always treat any user-supplied quantity as untrusted and enforce strict rules for minimums, maximums, and expected ranges before the value is used in any operation.
Impacto no mundo real

Real-world CVEs caused by CWE-1284

  • CVE-2019-19911

    Chain: Python library does not limit the resources used to process images that specify a very large number of bands (CWE-1284), leading to excessive memory consumption (CWE-789) or an integer overflow (CWE-190).

  • CVE-2008-1440

    lack of validation of length field leads to infinite loop

  • CVE-2008-2374

    lack of validation of string length fields allows memory consumption or buffer over-read

Como os atacantes a exploram

Trajeto do atacante passo a passo

  1. 1

    This example demonstrates a shopping interaction in which the user is free to specify the quantity of items to be purchased and a total is calculated.

  2. 2

    The user has no control over the price variable, however the code does not prevent a negative value from being specified for quantity. If an attacker were to provide a negative value, then the user would have their account credited instead of debited.

  3. 3

    This example asks the user for a height and width of an m X n game board with a maximum dimension of 100 squares.

  4. 4

    While this code checks to make sure the user cannot specify large, positive integers and consume too much memory, it does not check for negative values supplied by the user. As a result, an attacker can perform a resource consumption (CWE-400) attack against this program by specifying two, large negative values that will not overflow, resulting in a very large memory allocation (CWE-789) and possibly a system crash. Alternatively, an attacker can provide very large negative values which will cause an integer overflow (CWE-190) and unexpected behavior will follow depending on how the values are treated in the remainder of the program.

Exemplo de código vulnerável

Vulnerable Java

This example demonstrates a shopping interaction in which the user is free to specify the quantity of items to be purchased and a total is calculated.

Vulnerável Java 
...
  public static final double price = 20.00;
  int quantity = currentUser.getAttribute("quantity");
  double total = price * quantity;
  chargeUser(total);
  ...
Exemplo de código seguro

Secure pseudo

Seguro 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-1284

  • Implementation Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does. When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue." Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
Sinais de deteção

How to detect CWE-1284

SAST High

Executar análise estática (SAST) na base de código à procura do padrão inseguro no fluxo de dados.

DAST Moderate

Executar testes dinâmicos de segurança de aplicações (DAST) contra o endpoint em execução.

Runtime Moderate

Monitorizar os registos em tempo de execução para traços de exceção invulgares, input malformado ou tentativas de contornar a autorização.

Code review Moderate

Revisão de código: sinalizar qualquer novo código que trate input desta superfície sem usar os ajudantes validados do framework.

Correção automática do Plexicus

O Plexicus deteta automaticamente o CWE-1284 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.

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Perguntas frequentes

Frequently asked questions

O que é o CWE-1284?

This vulnerability occurs when an application accepts user input meant to define a quantity—like a number, size, or count—but fails to properly check if that value is safe and reasonable before using it.

Qual a gravidade do CWE-1284?

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-1284?

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

Como posso prevenir o CWE-1284?

Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does. When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and…

Como é que o Plexicus deteta e corrige o CWE-1284?

O motor SAST do Plexicus correlaciona a assinatura de fluxo de dados do CWE-1284 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-1284?

A MITRE publica a definição canónica em https://cwe.mitre.org/data/definitions/1284.html. Pode também consultar a documentação da OWASP e do NIST para orientações adjacentes.

Fraquezas relacionadas

Weaknesses related to CWE-1284

CWE-20 Pai

Improper Input Validation

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CWE-102 Irmão

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CWE-103 Irmão

Struts: Incomplete validate() Method Definition

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CWE-104 Irmão

Struts: Form Bean Does Not Extend Validation Class

This vulnerability occurs in Apache Struts applications when a form bean class does not properly extend the framework's validation class.…

CWE-105 Irmão

Struts: Form Field Without Validator

This vulnerability occurs when a Struts application form contains an input field that lacks a corresponding validator, leaving it open to…

CWE-106 Irmão

Struts: Plug-in Framework not in Use

This weakness occurs when a Java application, particularly one using the Struts framework, does not implement a structured input…

CWE-107 Irmão

Struts: Unused Validation Form

This vulnerability occurs when a Struts application contains validation form definitions that are no longer linked to any active form or…

CWE-108 Irmão

Struts: Unvalidated Action Form

In Apache Struts, every Action Form that processes user input must have a corresponding validation form configured. Missing this…

CWE-109 Irmão

Struts: Validator Turned Off

This vulnerability occurs when an application built with Apache Struts intentionally disables its built-in validation framework. By…

Recursos

Further reading

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