parlov-elicit 0.5.0

//! `LowPrivilegeElicitation` -- probes using the operator's own credential as-is.
//!
//! Sends both the baseline and probe requests with `ctx.headers` unmodified. The
//! oracle signal is the server returning 403 for existing resources the caller
//! cannot access versus 404 for nonexistent ones.

use http::Method;
use parlov_core::{
    always_applicable, NormativeStrength, OracleClass, SignalSurface, Technique, Vector,
};

use crate::strategy::Strategy;
use crate::types::{ProbeSpec, RiskLevel, StrategyMetadata};
use crate::util::build_pair;
use crate::ScanContext;

static METADATA: StrategyMetadata = StrategyMetadata {
    strategy_id: "low-privilege-elicit",
    strategy_name: "Low Privilege Elicitation",
    risk: RiskLevel::Safe,
};

static TECHNIQUE: Technique = Technique {
    id: "low-privilege",
    name: "Low-privilege credential probe",
    oracle_class: OracleClass::Existence,
    vector: Vector::StatusCodeDiff,
    strength: NormativeStrength::Should,
    // 404/404 from a normalizing server is NoSignal, not Contradictory.
    normalization_weight: None,
    inverted_signal_weight: None,
    method_relevant: false,
    parser_relevant: false,
    applicability: always_applicable,
    contradiction_surface: SignalSurface::Status,
};

/// Elicits existence differentials using the caller's own credential on both sides.
pub struct LowPrivilegeElicitation;

impl Strategy for LowPrivilegeElicitation {
    fn metadata(&self) -> &'static StrategyMetadata {
        &METADATA
    }

    fn technique_def(&self) -> &'static Technique {
        &TECHNIQUE
    }

    fn methods(&self) -> &[Method] {
        &[Method::GET, Method::HEAD]
    }

    fn is_applicable(&self, ctx: &ScanContext) -> bool {
        ctx.headers.contains_key(http::header::AUTHORIZATION)
    }

    fn generate(&self, ctx: &ScanContext) -> Vec<ProbeSpec> {
        let mut specs = Vec::with_capacity(2);
        for method in [Method::GET, Method::HEAD] {
            let pair = build_pair(
                ctx,
                method,
                ctx.headers.clone(),
                ctx.headers.clone(),
                None,
                METADATA.clone(),
                TECHNIQUE,
            );
            specs.push(ProbeSpec::Pair(pair));
        }
        specs
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::test_utils::{ctx_with_auth, minimal_ctx};

    #[test]
    fn risk_is_safe() {
        assert_eq!(LowPrivilegeElicitation.risk(), RiskLevel::Safe);
    }

    #[test]
    fn is_applicable_false_without_auth() {
        assert!(!LowPrivilegeElicitation.is_applicable(&minimal_ctx()));
    }

    #[test]
    fn is_applicable_true_with_auth() {
        assert!(LowPrivilegeElicitation.is_applicable(&ctx_with_auth()));
    }

    #[test]
    fn generate_returns_two_items() {
        assert_eq!(LowPrivilegeElicitation.generate(&ctx_with_auth()).len(), 2);
    }

    #[test]
    fn both_sides_carry_authorization_header() {
        let specs = LowPrivilegeElicitation.generate(&ctx_with_auth());
        let ProbeSpec::Pair(pair) = &specs[0] else {
            panic!("expected Pair")
        };
        assert!(pair
            .baseline
            .headers
            .get(http::header::AUTHORIZATION)
            .is_some());
        assert!(pair
            .probe
            .headers
            .get(http::header::AUTHORIZATION)
            .is_some());
    }

    #[test]
    fn technique_strength_is_should() {
        let specs = LowPrivilegeElicitation.generate(&ctx_with_auth());
        assert_eq!(specs[0].technique().strength, NormativeStrength::Should);
    }

    #[test]
    fn normalization_weight_is_none() {
        assert_eq!(TECHNIQUE.normalization_weight, None);
    }

    #[test]
    fn inverted_signal_weight_is_none() {
        assert_eq!(TECHNIQUE.inverted_signal_weight, None);
    }
}