Vulnerable Components in Axum with Basic Auth

Using HTTP Basic Authentication in an Axum application introduces several components that, when combined, can expose the application to common API security risks identified by scanners like middleBrick. This specific combination affects three dimensions: authentication implementation, authorization boundaries, and input handling.

At the authentication layer, Basic Auth transmits credentials as base64-encoded plaintext in the Authorization header. If the application does not enforce HTTPS, credentials are easily intercepted. In Axum, developers might add a middleware that checks the header but forget to validate the presence of TLS, leaving a gap in encryption. middleBrick checks for encryption and flags missing transport-layer protection as a high-severity finding.

On the authorization dimension, Basic Auth typically identifies a user or service, but Axum routes often lack fine-grained checks to ensure the authenticated subject is allowed to access the specific resource. This can lead to Broken Level of Authorization (BOLA), also known as Insecure Direct Object References (IDOR). For example, a route like /users/{user_id}/profile might verify a token but not confirm that the requesting user matches the user_id path parameter. middleBrick’s BOLA/IDOR checks test these scenarios by probing endpoints with different identifiers to detect unauthorized data access.

In the input validation and unsafe consumption dimension, Basic Auth only provides identity, not trust. Axum handlers that parse query parameters or body payloads without strict validation may be vulnerable to injection or malformed input attacks. If the application reuses the authenticated identity to construct file paths, database queries, or admin commands without sanitization, it may open paths to injection or SSRF. middleBrick tests input validation by sending unexpected payloads and examines whether the API exposes stack traces or internal details in error responses, which would indicate unsafe consumption patterns.

Additionally, Basic Auth does not include built-in replay protection. If Axum does not implement nonce or timestamp checks, an attacker could capture and replay valid requests. middleBrick’s rate-limiting checks look for missing or weak controls around request frequency and token replay, which can result in findings under Authentication and Rate Limiting categories.

Finally, because Basic Auth credentials are static, compromised credentials remain valid until explicitly rotated. If an Axum application lacks mechanisms for short-lived tokens or automatic revocation, the exposure window increases. middleBrick’s Inventory Management checks examine whether the API surface documents credential lifecycle and whether there are indicators of stale or excessive privileges, tying findings to compliance frameworks such as OWASP API Top 10 and SOC2.

Remediation focuses on enforcing HTTPS, validating identity-to-permission mapping, and hardening input handling while continuing to use Basic Auth credentials as a simple identifier.

Enforce HTTPS and validate transport

Always terminate TLS before Axum sees the request. In middleware, verify that the request uses HTTPS and reject cleartext HTTP. A minimal Axum middleware snippet:

use axum::{http::Request, async_trait, extract::Extension, middleware::Next, response::Response};
use std::convert::Infallible;

pub async fn require_https(req: Request<B>, next: Next<B>) -> Result<Response, (axum::http::StatusCode, String)> {
    if req.uri().scheme().map(|s| s == "https").unwrap_or(false) {
        Ok(next.run(req).await)
    } else {
        Err((axum::http::StatusCode::FORBIDDEN, "HTTPS required".to_string()))
    }
}

use axum::{Extension, Json};
use std::sync::Arc;

struct User { id: u64, role: String }
struct AppState { users: Arc<std::collections::HashMap<String, User>> }

async fn profile_handler(
    Extension(state): Extension<Arc<AppState>>,
    auth_header: Option<axum::http::header::Authorization<axum::http::header::Basic>>,
    Path(user_id): Path<u64>,
) -> Result<Json<User>, (axum::http::StatusCode, String)> {
    let creds = auth_header.ok_or((axum::http::StatusCode::UNAUTHORIZED, "Missing auth"))?;
    let user = state.users.get(&creds.password())
        .ok_or((axum::http::StatusCode::FORBIDDEN, "Invalid credentials"))?;
    if user.id != user_id {
        return Err((axum::http::StatusCode::FORBIDDEN, "Cannot access this resource".to_string()));
    }
    Ok(Json(user.clone()))
}

use axum::{Extension, Json, http::StatusCode};
use serde::{Deserialize, Serialize};
use validator::Validate;

#[derive(Deserialize, Validate)]
struct ProfileUpdate {
    #[validate(length(min = 1))]
    display_name: String,
}

async fn update_profile(
    Extension(state): Extension<Arc<AppState>>,
    auth_header: Option<axum::http::header::Authorization<axum::http::header::Basic>>,
    Json(payload): Json<ProfileUpdate>,
) -> Result<StatusCode, (StatusCode, String)> {
    payload.validate().map_err(|e| (StatusCode::BAD_REQUEST, e.to_string()))?;
    // Proceed with update using authenticated identity from auth_header
    Ok(StatusCode::NO_CONTENT)
}

use axum::http::HeaderMap;

fn is_request_fresh(headers: &HeaderMap) -> bool {
    if let Some(ts) = headers.get("X-Request-Timestamp") {
        if let Ok(ts_str) = ts.to_str() {
            if let Ok(ts) = ts_str.parse::() {
                let now = std::time::SystemTime::now()
                    .duration_since(std::time::UNIX_EPOCH)
                    .unwrap()
                    .as_secs();
                return now.saturating_sub(ts) <= 300; // 5 minutes
            }
        }
    }
    false
}