parlov-elicit 0.4.0

//! `OversizedBodyElicitation` -- probes with a spoofed `Content-Length` declaring 10 MB.
//!
//! Sends `Content-Length: 10485760` on the probe request with a small actual
//! body. Servers that enforce payload size limits before existence-checking
//! return 413 for a resource that exists versus 404 for a nonexistent one.

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

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

/// Declared body size for the probe -- 10 MiB, never actually sent.
const SPOOFED_CONTENT_LENGTH: &str = "10485760";

fn metadata() -> StrategyMetadata {
    StrategyMetadata {
        strategy_id: "oversized-body-elicit",
        strategy_name: "Oversized Body Elicitation",
        risk: RiskLevel::MethodDestructive,
    }
}

fn technique() -> Technique {
    Technique {
        id: "oversized-body",
        name: "Oversized Content-Length probe",
        oracle_class: OracleClass::Existence,
        vector: Vector::StatusCodeDiff,
        strength: NormativeStrength::Should,
    }
}

/// Elicits existence differentials by spoofing a large `Content-Length` on probe requests.
pub struct OversizedBodyElicitation;

impl Strategy for OversizedBodyElicitation {
    fn id(&self) -> &'static str {
        "oversized-body-elicit"
    }

    fn name(&self) -> &'static str {
        "Oversized Body Elicitation"
    }

    fn risk(&self) -> RiskLevel {
        RiskLevel::MethodDestructive
    }

    fn methods(&self) -> &[Method] {
        &[Method::POST, Method::PUT, Method::PATCH]
    }

    fn is_applicable(&self, _ctx: &ScanContext) -> bool {
        true
    }

    fn generate(&self, ctx: &ScanContext) -> Vec<ProbeSpec> {
        let body = Some(json_body(&[]));
        let mut specs = Vec::with_capacity(3);
        for method in [Method::POST, Method::PUT, Method::PATCH] {
            let baseline_headers =
                clone_headers_with(&ctx.headers, "content-type", "application/json");
            let probe_headers = clone_headers_with(
                &clone_headers_with(&ctx.headers, "content-type", "application/json"),
                "content-length",
                SPOOFED_CONTENT_LENGTH,
            );
            let pair = build_pair(
                ctx, method, baseline_headers, probe_headers,
                body.clone(), metadata(), technique(),
            );
            specs.push(ProbeSpec::Pair(pair));
        }
        specs
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use http::HeaderMap;

    fn make_ctx() -> ScanContext {
        ScanContext {
            target: "https://api.example.com/users/{id}".to_string(),
            baseline_id: "1001".to_string(),
            probe_id: "9999".to_string(),
            headers: HeaderMap::new(),
            max_risk: RiskLevel::MethodDestructive,
            known_duplicate: None,
            state_field: None,
            alt_credential: None,
            body_template: None,
        }
    }

    #[test]
    fn risk_is_method_destructive() {
        assert_eq!(OversizedBodyElicitation.risk(), RiskLevel::MethodDestructive);
    }

    #[test]
    fn generate_returns_three_items() {
        assert_eq!(OversizedBodyElicitation.generate(&make_ctx()).len(), 3);
    }

    #[test]
    fn probe_has_spoofed_content_length() {
        let specs = OversizedBodyElicitation.generate(&make_ctx());
        let ProbeSpec::Pair(pair) = &specs[0] else { panic!("expected Pair") };
        assert_eq!(pair.probe.headers.get("content-length").unwrap(), "10485760");
    }

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