CWE-385 Base Incompleto Medium likelihood

Covert Timing Channel

A covert timing channel is a security flaw where an attacker can deduce secret information by observing how long certain operations take to execute. Instead of directly reading data, they analyze…

Definição

What is CWE-385?

A covert timing channel is a security flaw where an attacker can deduce secret information by observing how long certain operations take to execute. Instead of directly reading data, they analyze timing variations in system behavior to infer protected details.
Attackers can exploit timing differences to learn secrets they shouldn't have access to. For instance, if a cryptographic function or a database query takes slightly longer under specific conditions, that delay can leak information about the internal state of the operation or the data being processed. Monitoring these subtle time variations allows an attacker to piece together sensitive information. This type of vulnerability is a classic example of a side-channel attack, specifically a timing channel. Common real-world signals include variations in a system's paging rate, the execution time of a transaction, or the delay in accessing a shared resource. Defending against these attacks requires ensuring that operations complete in constant time, regardless of the input or secret data involved.
Impacto no mundo real

Real-world CVEs caused by CWE-385

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, the attacker observes how long an authentication takes when the user types in the correct password.

  2. 2

    When the attacker tries their own values, they can first try strings of various length. When they find a string of the right length, the computation will take a bit longer, because the for loop will run at least once. Additionally, with this code, the attacker can possibly learn one character of the password at a time, because when they guess the first character right, the computation will take longer than a wrong guesses. Such an attack can break even the most sophisticated password with a few hundred guesses.

  3. 3

    Note that in this example, the actual password must be handled in constant time as far as the attacker is concerned, even if the actual password is of an unusual length. This is one reason why it is good to use an algorithm that, among other things, stores a seeded cryptographic one-way hash of the password, then compare the hashes, which will always be of the same length.

Exemplo de código vulnerável

Vulnerable Python

When the attacker tries their own values, they can first try strings of various length. When they find a string of the right length, the computation will take a bit longer, because the for loop will run at least once. Additionally, with this code, the attacker can possibly learn one character of the password at a time, because when they guess the first character right, the computation will take longer than a wrong guesses. Such an attack can break even the most sophisticated password with a few hundred guesses.

Vulnerável Python 
def validate_password(actual_pw, typed_pw): 
  		if len(actual_pw) <> len(typed_pw): 
  			return 0
  		for i in len(actual_pw): 
  			if actual_pw[i] <> typed_pw[i]: 
  				return 0
  		return 1
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-385

  • Architecture and Design Whenever possible, specify implementation strategies that do not introduce time variances in operations.
  • Implementation Often one can artificially manipulate the time which operations take or -- when operations occur -- can remove information from the attacker.
  • Implementation It is reasonable to add artificial or random delays so that the amount of CPU time consumed is independent of the action being taken by the application.
Sinais de deteção

How to detect CWE-385

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-385 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-385?

A covert timing channel is a security flaw where an attacker can deduce secret information by observing how long certain operations take to execute. Instead of directly reading data, they analyze timing variations in system behavior to infer protected details.

Qual a gravidade do CWE-385?

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-385?

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

Como posso prevenir o CWE-385?

Whenever possible, specify implementation strategies that do not introduce time variances in operations. Often one can artificially manipulate the time which operations take or -- when operations occur -- can remove information from the attacker.

Como é que o Plexicus deteta e corrige o CWE-385?

O motor SAST do Plexicus correlaciona a assinatura de fluxo de dados do CWE-385 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-385?

A MITRE publica a definição canónica em https://cwe.mitre.org/data/definitions/385.html. Pode também consultar a documentação da OWASP e do NIST para orientações adjacentes.

Fraquezas relacionadas

Weaknesses related to CWE-385

CWE-514 Pai

Covert Channel

A covert channel is a hidden communication path that allows data to be transmitted in a way that bypasses the system's intended security…

CWE-515 Irmão

Covert Storage Channel

A covert storage channel is a type of security flaw where one process secretly encodes data into a shared system resource (like a file,…

Recursos

Further reading

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