Open Redirect in Axum with Dynamodb

An open redirect occurs when an application accepts a user-controlled URL or path parameter and uses it directly in a redirect response without validation. In an Axum application that integrates with DynamoDB, this risk typically arises when route parameters or query strings are used both to look up data in DynamoDB and to influence navigation or redirection logic.

Consider an Axum handler that accepts a user_id path parameter, retrieves a user record from DynamoDB, and then redirects the client to a URL stored in a field such as profile_url or return_to. If the application trusts the data returned from DynamoDB or a client-supplied redirect target without strict allowlisting, an attacker can craft a link that causes the application to redirect to a malicious site. For example, an attacker might register or update a profile in DynamoDB with a malicious profile_url, or supply a manipulated user_id that maps to a record containing a harmful redirect target.

Because Axum applications often combine routing, data access, and response generation, the interaction with DynamoDB can inadvertently expose redirect logic. If the redirect URL is constructed by concatenating user-controlled values or by directly using a field from a DynamoDB item, the application may become an open redirect vector. This becomes especially dangerous when the redirect is used in authentication flows (e.g., post-login return URLs) or in multi-step workflows where trust boundaries are not clearly enforced.

In the context of middleBrick’s security checks, an unauthenticated scan can detect patterns where redirect-related endpoints rely on untrusted data sourced from DynamoDB without proper validation. The scanner does not assume the data stored in DynamoDB is inherently safe; it flags instances where a response includes a redirect (such as an HTTP 302) whose target originates from a DynamoDB field or is influenced by request parameters that map to DynamoDB queries.

Real-world examples align with common OWASP API Top 10 and CWE categories, such as CWE-601 (URL Redirection to Untrusted Site). An attacker may use such a flaw for phishing campaigns or to bypass intended navigation flows. Therefore, when Axum routes interact with DynamoDB, it is essential to treat any data used in redirection as untrusted and to enforce strict allowlists and canonicalization before using it in a redirect context.

To mitigate open redirect risks in an Axum application that uses DynamoDB, apply strict validation and canonicalization to any data used in redirect decisions. Prefer allowlisting known-safe targets over using raw values from DynamoDB, and ensure that redirect URLs are constructed in a controlled manner.

Below are concrete Axum handler examples using the AWS SDK for Rust (aws-sdk-dynamodb). These examples demonstrate safe patterns for retrieving items and constructing responses without introducing open redirect vulnerabilities.

use aws_sdk_dynamodb::Client;
use axum::{response::Redirect, routing::get, Router};
use std::net::SocketAddr;

async fn get_user_profile(
    client: &Client,
    user_id: &str,
) -> Result {
    let resp = client
        .get_item()
        .table_name("users")
        .key("user_id".to_string(), aws_sdk_dynamodb::types::AttributeValue::S(user_id.to_string()))
        .send()
        .await
        .map_err(|e| e.to_string())?;

    let item = resp.item().ok_or("User not found")?;
    // Safely extract fields; do not use raw user-controlled URLs for redirects
    let email = item.get("email")
        .and_then(|v| v.as_s().ok())
        .map(|s| s.to_string())
        .ok_or("Missing email")?;

    // Use a canonical, internal endpoint instead of a user-supplied URL
    Ok(format!("/dashboard?email={}", email))
}

#[tokio::main]
async fn main() {
    let config = aws_config::load_from_env().await;
    let client = Client::new(&config);

    let app = Router::new()
        .route("/profile/:user_id", get(|path: axum::extract::Path<(String,)>| async move {
            let user_id = path.0;
            match get_user_profile(&client, &user_id).await {
                Ok(url) => Redirect::temporary(&url),
                Err(_) => (),
            }
        }));

    let addr = SocketAddr::from(([127, 0, 0, 1], 3000));
    axum::Server::bind(&addr)
        .serve(app.into_make_service())
        .await
        .unwrap();
}

If your application must store or use redirect targets, store only relative paths or route names in DynamoDB, and map them to canonical URLs on the server side. Avoid storing full external URLs that can be manipulated.

use aws_sdk_dynamodb::Client;
use axum::response::Redirect;

async fn safe_redirect_target(
    client: &Client,
    user_id: &str,
) -> Result {
    let resp = client
        .get_item()
        .table_name("users")
        .key("user_id".to_string(), aws_sdk_dynamodb::types::AttributeValue::S(user_id.to_string()))
        .send()
        .await
        .map_err(|e| e.to_string())?;

    let item = resp.item().ok_or("User not found")?;
    let role = item.get("role")
        .and_then(|v| v.as_s().ok())
        .map(|s| s.to_string())
        .ok_or("Missing role")?;

    // Map server-side roles to safe routes; never use raw external URLs from DynamoDB
    let target = match role.as_str() {
        "admin" => "/admin/dashboard",
        "user" => "/user/home",
        _ => "/home",
    };

    Ok(Redirect::temporary(target))
}

Additionally, apply input validation on any parameters used to query DynamoDB, and prefer parameterized queries to avoid injection risks that could lead to unintended data retrieval affecting redirect decisions. Using the AWS SDK’s built-in serializers and strongly-typed models helps maintain control over how data is interpreted and used in your application logic.