Falhas do tipo CWE-331

101 resultados

Entropia insuficiente em geração de números aleatórios

A fraqueza ocorre quando o software usa um gerador de números aleatórios ou pseudoaleatórios com entropia insuficiente para fins críticos de segurança, como gerar tokens, chaves criptográficas ou identificadores únicos. Um atacante consegue prever ou reproduzir esses valores, comprometendo toda a segurança que depende dessa aleatoriedade.

Exemplo

Uma aplicação usa Math.random() em JavaScript para gerar um token de sessão, ou confia em valores de /dev/urandom em uma máquina virtual com pouca entrada de entropia no boot. Em ambos os casos, um atacante consegue enumerar tokens válidos ou quebrar a criptografia que depende desses números.

Como mitigar

Use sempre geradores criptograficamente seguros apropriados para seu contexto: java.security.SecureRandom em Java, secrets.token_hex() em Python, crypto.getRandomBytes() em Node.js, ou /dev/urandom em sistemas Unix. Garanta que o sistema operacional coleta entropia suficiente (verifique /proc/sys/kernel/random/entropy_avail em Linux).

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