CWE-760 Variante Incompleto

Use of a One-Way Hash with a Predictable Salt

This vulnerability occurs when an application uses a one-way hash (like for password storage) but combines it with a predictable or easily guessed salt. This undermines the security benefit of…

Definição

What is CWE-760?

This vulnerability occurs when an application uses a one-way hash (like for password storage) but combines it with a predictable or easily guessed salt. This undermines the security benefit of salting, making pre-computed attack methods like rainbow tables highly effective.
Using a predictable salt, such as a username or a static string, allows attackers to bypass the primary defense salting provides. Attackers can pre-generate massive lookup tables (rainbow tables) for that specific salt, enabling them to quickly reverse hashes and recover credentials. This effectively nullifies the security advantage that a random, unique salt is meant to deliver. It's important to understand that even a strong, random salt is not a complete solution against determined attackers with significant resources, as hashing algorithms are designed for speed. Modern password cracking using cloud or specialized hardware can still be effective. For robust protection, consider adaptive, computationally expensive hash functions (like Argon2, scrypt, or bcrypt) designed specifically for passwords. Identifying and fixing these predictable salt patterns across a large codebase can be challenging; an ASPM platform like Plexicus can automatically detect such flaws via SAST and use AI to provide specific remediation guidance, streamlining the fix process.
Impacto no mundo real

Real-world CVEs caused by CWE-760

  • CVE-2008-4905

    Blogging software uses a hard-coded salt when calculating a password hash.

  • CVE-2002-1657

    Database server uses the username for a salt when encrypting passwords, simplifying brute force attacks.

  • CVE-2001-0967

    Server uses a constant salt when encrypting passwords, simplifying brute force attacks.

  • CVE-2005-0408

    chain: product generates predictable MD5 hashes using a constant value combined with username, allowing authentication bypass.

Como os atacantes a exploram

Trajeto do atacante passo a passo

  1. 1

    Identificar um caminho de código que trata input não confiável sem validação.

  2. 2

    Criar um payload que explora o comportamento inseguro — injeção, traversal, overflow ou abuso de lógica.

  3. 3

    Entregar o payload através de um pedido normal e observar a reação da aplicação.

  4. 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.

Vulnerável pseudo 
// 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

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-760

  • Architecture and Design Use an adaptive hash function that can be configured to change the amount of computational effort needed to compute the hash, such as the number of iterations ("stretching") or the amount of memory required. Some hash functions perform salting automatically. These functions can significantly increase the overhead for a brute force attack compared to intentionally-fast functions such as MD5. For example, rainbow table attacks can become infeasible due to the high computing overhead. Finally, since computing power gets faster and cheaper over time, the technique can be reconfigured to increase the workload without forcing an entire replacement of the algorithm in use. Some hash functions that have one or more of these desired properties include bcrypt [REF-291], scrypt [REF-292], and PBKDF2 [REF-293]. While there is active debate about which of these is the most effective, they are all stronger than using salts with hash functions with very little computing overhead. Note that using these functions can have an impact on performance, so they require special consideration to avoid denial-of-service attacks. However, their configurability provides finer control over how much CPU and memory is used, so it could be adjusted to suit the environment's needs.
  • Implementation If a technique that requires extra computational effort can not be implemented, then for each password that is processed, generate a new random salt using a strong random number generator with unpredictable seeds. Add the salt to the plaintext password before hashing it. When storing the hash, also store the salt. Do not use the same salt for every password.
Sinais de deteção

How to detect CWE-760

Automated Static Analysis High

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.)

Correção automática do Plexicus

O Plexicus deteta automaticamente o CWE-760 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-760?

This vulnerability occurs when an application uses a one-way hash (like for password storage) but combines it with a predictable or easily guessed salt. This undermines the security benefit of salting, making pre-computed attack methods like rainbow tables highly effective.

Qual a gravidade do CWE-760?

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-760?

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

Como posso prevenir o CWE-760?

Use an adaptive hash function that can be configured to change the amount of computational effort needed to compute the hash, such as the number of iterations ("stretching") or the amount of memory required. Some hash functions perform salting automatically. These functions can significantly increase the overhead for a brute force attack compared to intentionally-fast functions such as MD5. For example, rainbow table attacks can become infeasible due to the high computing overhead. Finally,…

Como é que o Plexicus deteta e corrige o CWE-760?

O motor SAST do Plexicus correlaciona a assinatura de fluxo de dados do CWE-760 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-760?

A MITRE publica a definição canónica em https://cwe.mitre.org/data/definitions/760.html. Pode também consultar a documentação da OWASP e do NIST para orientações adjacentes.

Fraquezas relacionadas

Weaknesses related to CWE-760

CWE-916 Pai

Use of Password Hash With Insufficient Computational Effort

This vulnerability occurs when a system protects passwords by hashing them, but uses a hashing algorithm that is too fast or…

CWE-759 Irmão

Use of a One-Way Hash without a Salt

This vulnerability occurs when a system uses a one-way hash function (like MD5 or SHA-256) to protect sensitive data like passwords, but…

Recursos

Further reading

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