Zennoxa Shield
Rules / Rust
SHIELD-RUST-010

Insecure randomness for security value

mediumRustCWE-338CVSS 5.9

What it detects

rand::random / thread_rng is not a CSPRNG guarantee for tokens, keys, or nonces.

How to fix

Use a CSPRNG (rand::rngs::OsRng / getrandom) for security-sensitive values.

Vulnerable — Shield flags thissession.rs
pub fn new_session_id() -> String {
    // Predictable PRNG seeds make these ids guessable.
    let id: u64 = rand::random();
    format!("sess-{:016x}", id)
}
Fixed — scans cleansession.rs
use rand::rngs::OsRng;
use rand::RngCore;

pub fn new_session_id() -> String {
    let mut bytes = [0u8; 16];
    OsRng.fill_bytes(&mut bytes);
    format!("sess-{}", hex::encode(bytes))
}

Both snippets are verified against the shipped scanner: the vulnerable one triggers SHIELD-RUST-010, the fixed one does not.

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SHIELD-RUST-010: Insecure randomness for security value — Zennoxa Shield