CWE-325 Base Rascunho

Missing Cryptographic Step

This vulnerability occurs when a software implementation skips a critical step in a cryptographic process, resulting in security that is significantly weaker than the intended algorithm provides.

Definição

What is CWE-325?

This vulnerability occurs when a software implementation skips a critical step in a cryptographic process, resulting in security that is significantly weaker than the intended algorithm provides.
Cryptographic algorithms are designed as a sequence of specific, interdependent steps. Each step serves a purpose, such as ensuring randomness, preventing pattern analysis, or binding data together securely. When a developer omits one of these steps—whether during key generation, encryption, decryption, or integrity verification—the entire cryptographic operation becomes fragile. The resulting system may appear to function normally but can be easily broken by attackers using well-known techniques, completely undermining the promised security. This flaw often stems from using incomplete code samples, misunderstanding algorithm specifications, or attempting to 'optimize' performance by removing so-called 'unnecessary' operations. To prevent it, developers should rely on reputable, high-level cryptographic libraries rather than implementing algorithms from scratch. Always follow the official algorithm specification or RFC meticulously, and use established test vectors to verify that every required step is correctly executed in the proper order.
Impacto no mundo real

Real-world CVEs caused by CWE-325

  • CVE-2001-1585

    Missing challenge-response step allows authentication bypass using public key.

Como os atacantes a exploram

Trajeto do atacante passo a passo

  1. 1

    The example code is taken from the HMAC engine inside the buggy OpenPiton SoC of HACK@DAC'21 [REF-1358]. HAMC is a message authentication code (MAC) that uses both a hash and a secret crypto key. The HMAC engine in HACK@DAC SoC uses the SHA-256 module for the calculation of the HMAC for 512 bits messages.

  2. 2

    However, this HMAC engine cannot handle messages that are longer than 512 bits. Moreover, a complete HMAC will contain an iterate hash function that breaks up a message into blocks of a fixed size and iterates over them with a compression function (e.g., SHA-256). Therefore, the implementation of the HMAC in OpenPiton SoC is incomplete. Such HMAC engines will not be used in real-world applications as the messages will usually be longer than 512 bits. For instance, OpenTitan offers a comprehensive HMAC implementation that utilizes a FIFO for temporarily storing the truncated message, as detailed in [REF-1359].

  3. 3

    To mitigate this, implement the iterative function to break up a message into blocks of a fixed size.

Exemplo de código vulnerável

Vulnerable Verilog

The example code is taken from the HMAC engine inside the buggy OpenPiton SoC of HACK@DAC'21 [REF-1358]. HAMC is a message authentication code (MAC) that uses both a hash and a secret crypto key. The HMAC engine in HACK@DAC SoC uses the SHA-256 module for the calculation of the HMAC for 512 bits messages.

Vulnerável Verilog 
**logic [511:0] bigData;** 
 ...

 hmac hmac(

```
   .clk_i(clk_i),
   .rst_ni(rst_ni && ~rst_4),
   .init_i(startHash && ~startHash_r),
   .key_i(key),
   .ikey_hash_i(ikey_hash), 
   .okey_hash_i(okey_hash), 
   .key_hash_bypass_i(key_hash_bypass),
```
.message_i(bigData),** 
   .hash_o(hash),
   .ready_o(ready),
   .hash_valid_o(hashValid)
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-325

  • 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-325

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-325 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-325?

This vulnerability occurs when a software implementation skips a critical step in a cryptographic process, resulting in security that is significantly weaker than the intended algorithm provides.

Qual a gravidade do CWE-325?

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-325?

MITRE lists the following affected platforms: Not Technology-Specific.

Como posso prevenir o CWE-325?

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-325?

O motor SAST do Plexicus correlaciona a assinatura de fluxo de dados do CWE-325 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-325?

A MITRE publica a definição canónica em https://cwe.mitre.org/data/definitions/325.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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