CWE-1023 Classe Incompleto

Incomplete Comparison with Missing Factors

This weakness occurs when a program compares two items but fails to check all the necessary attributes that define their true relationship. The incomplete check can cause the software to treat…

Definição

What is CWE-1023?

This weakness occurs when a program compares two items but fails to check all the necessary attributes that define their true relationship. The incomplete check can cause the software to treat different items as identical or make incorrect security decisions.
Incomplete comparisons happen when a developer writes a check that only validates a subset of an object's or user's identity. For example, a system might authenticate a user by checking only a username without verifying the associated password or session token, or it might compare data objects using only an ID field while ignoring a critical 'type' or 'state' field. This creates a logical gap where two distinct entities can be incorrectly evaluated as equivalent. This flaw directly undermines security and logic by allowing unauthorized access, privilege escalation, or data corruption. Attackers can exploit it by providing an entity that matches on the checked factors but differs maliciously on the unchecked ones. To prevent this, always ensure comparison functions validate every unique and security-relevant property that defines an entity's complete identity within that specific context.
Impacto no mundo real

Real-world CVEs caused by CWE-1023

  • CVE-2005-2782

    PHP remote file inclusion in web application that filters "http" and "https" URLs, but not "ftp".

  • CVE-2014-6394

    Product does not prevent access to restricted directories due to partial string comparison with a public directory

Como os atacantes a exploram

Trajeto do atacante passo a passo

  1. 1

    Consider an application in which Truck objects are defined to be the same if they have the same make, the same model, and were manufactured in the same year.

  2. 2

    Here, the equals() method only checks the make and model of the Truck objects, but the year of manufacture is not included.

  3. 3

    This example defines a fixed username and password. The AuthenticateUser() function is intended to accept a username and a password from an untrusted user, and check to ensure that it matches the username and password. If the username and password match, AuthenticateUser() is intended to indicate that authentication succeeded.

  4. 4

    In AuthenticateUser(), the strncmp() call uses the string length of an attacker-provided inPass parameter in order to determine how many characters to check in the password. So, if the attacker only provides a password of length 1, the check will only examine the first byte of the application's password before determining success.

  5. 5

    As a result, this partial comparison leads to improper authentication (CWE-287).

Exemplo de código vulnerável

Vulnerable Java

Consider an application in which Truck objects are defined to be the same if they have the same make, the same model, and were manufactured in the same year.

Vulnerável Java 
public class Truck {
  		private String make;
  		private String model;
  		private int year;
  		public boolean equals(Object o) {
  				if (o == null) return false;
  				if (o == this) return true;
  				if (!(o instanceof Truck)) return false;
  				Truck t = (Truck) o;
  				return (this.make.equals(t.getMake()) && this.model.equals(t.getModel()));
  		}
  }
Payload do atacante

Any of these passwords would still cause authentication to succeed for the "admin" user:

Payload do atacante 
p
  pa
  pas
  pass
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-1023

  • Testing Thoroughly test the comparison scheme before deploying code into production. Perform positive testing as well as negative testing.
Sinais de deteção

How to detect CWE-1023

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-1023 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-1023?

This weakness occurs when a program compares two items but fails to check all the necessary attributes that define their true relationship. The incomplete check can cause the software to treat different items as identical or make incorrect security decisions.

Qual a gravidade do CWE-1023?

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-1023?

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

Como posso prevenir o CWE-1023?

Thoroughly test the comparison scheme before deploying code into production. Perform positive testing as well as negative testing.

Como é que o Plexicus deteta e corrige o CWE-1023?

O motor SAST do Plexicus correlaciona a assinatura de fluxo de dados do CWE-1023 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-1023?

A MITRE publica a definição canónica em https://cwe.mitre.org/data/definitions/1023.html. Pode também consultar a documentação da OWASP e do NIST para orientações adjacentes.

Fraquezas relacionadas

Weaknesses related to CWE-1023

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CWE-1039 Irmão

Inadequate Detection or Handling of Adversarial Input Perturbations in Automated Recognition Mechanism

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Floating Point Comparison with Incorrect Operator

This vulnerability occurs when code compares two floating-point numbers using direct equality operators (like == or !=) without accounting…

CWE-1254 Irmão

Incorrect Comparison Logic Granularity

This vulnerability occurs when a system compares sensitive data, like passwords or authentication tokens, piece-by-piece instead of as a…

CWE-183 Irmão

Permissive List of Allowed Inputs

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CWE-185 Irmão

Incorrect Regular Expression

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CWE-581 Irmão

Object Model Violation: Just One of Equals and Hashcode Defined

This vulnerability occurs when a Java class defines either the equals() method or the hashCode() method, but not both, breaking a…

Recursos

Further reading

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