Broken Authentication in Rocket with Dynamodb

Broken Authentication in a Rocket service that uses DynamoDB typically arises from a mismatch between authentication enforcement in the application layer and how identity data is modeled and retrieved from DynamoDB. Rocket does not provide built-in authentication; it expects the developer to implement guards and extract identity from request state. If the developer relies on incomplete or inconsistent data from DynamoDB when establishing authentication, the attack surface expands.

One common pattern is querying DynamoDB by a user-supplied identifier (e.g., username or email) without ensuring the caller is authorized to view that record. Because DynamoDB is a NoSQL store, queries that use a non-key attribute require a scan or a secondary index. Using a scan or an unpartitioned query for authentication lookups can be slow and error-prone, and it may inadvertently expose user enumeration risks if responses differ based on existence or attributes. More critically, if the application uses the same DynamoDB table for both authentication metadata and authorization checks without scoping access by a partition key that maps to the authenticated subject, horizontal privilege escalation becomes possible: one user can iterate or query another user’s row if the request is not bound to a specific identity context.

In Rocket, routes are async and rely on request guards to extract claims or user IDs. If a route guard fetches a user from DynamoDB using an ID extracted from a bearer token but does not validate that the token’s subject matches the retrieved item’s ownership partition, an attacker can substitute identifiers. For example, guessing or iterating user IDs in the request path or tampering with JSON Web Token (JWT) subject claims can lead to unauthorized access to another user’s profile or settings stored in DynamoDB. This aligns with the Broken Authentication category in the OWASP API Top 10 and can be detected as BOLA/IDOR by middleBrick’s 12 security checks, which test unauthenticated and authenticated scenarios to identify insecure direct object references.

Additionally, insufficient protection of credentials at rest or in transit when stored in DynamoDB can weaken authentication. If passwords or secrets are stored in DynamoDB without proper protective measures, exposure through misconfigured IAM policies or unintended data exports increases authentication risk. middleBrick’s Authentication check inspects whether endpoints correctly verify credentials, and its Data Exposure checks look for sensitive attributes returned in API responses. The LLM/AI Security probes also test for system prompt leakage and output exposure that could indirectly reveal authentication logic or user data, complementing the standard authentication tests.

Because middleBrick scans the unauthenticated attack surface in 5–15 seconds and runs checks in parallel, it can quickly surface these authentication inconsistencies across the API surface. Findings include severity-ranked guidance to tighten guard implementations, scope DynamoDB queries to the authenticated subject, and align token claims with data ownership, helping teams address Broken Authentication before it leads to unauthorized access.

To remediate Broken Authentication when using DynamoDB in Rocket, ensure that every authenticated request derives the user identity from a trusted source (such as a validated JWT) and uses that identity to construct scoped queries against DynamoDB. Avoid relying on user-supplied identifiers alone, and always map the authenticated subject to a partition key that isolates their data.

Below are concrete Rust code examples using the official AWS SDK for Rust and Rocket guards. The examples assume a users table with a partition key user_id and an index on email for lookup during sign-in.

Secure Sign-In with Email Lookup

use aws_sdk_dynamodb::Client;
use rocket::State;
use serde::{Deserialize, Serialize};

#[derive(Debug, Deserialize, Serialize)]
struct User {
    user_id: String,
    email: String,
    // other fields omitted
}

async fn find_user_by_email(client: &Client, email: &str) -> Result {
    let resp = client.scan()
        .table_name("users")
        .filter_expression("email = :email")
        .expression_attribute_values(":email", aws_sdk_dynamodb::AttributeValue::S(email.to_string()))
        .send()
        .await?;

    let items = resp.items().unwrap_or_default();
    // Extract first matching item and map to User
    if let Some(item) = items.first() {
        Ok(User {
            user_id: item.get("user_id").and_then(|v| v.as_s().ok()).unwrap_or(&"").to_string(),
            email: item.get("email").and_then(|v| v.as_s().ok()).unwrap_or(&"").to_string(),
        })
    } else {
        Err(aws_sdk_dynamodb::error::SdkError::ServiceError {
            err: aws_sdk_dynamodb::error::ScanError::builder().build(),
            raw: Default::default(),
        })
    }
}

use rocket::request::{self, FromRequest, Outcome};
use rocket::Request;
use aws_sdk_dynamodb::Client;

struct AuthenticatedUser {
    user_id: String,
}

#[rocket::async_trait]
impl<'r> FromRequest<'r> for AuthenticatedUser {
    type Error = ();

    async fn from_request(request: &'r Request<'_>) -> request::Outcome {
        let token = match request.headers().get_one("Authorization") {
            Some(t) => t.strip_prefix("Bearer ").unwrap_or(t),
            None => return Outcome::Failure((rocket::http::Status::Unauthorized, ())),
        };

        // Validate token and extract subject (e.g., via a JWT library)
        let subject = validate_token_and_get_subject(token).unwrap_or_default();
        if subject.is_empty() {
            return Outcome::Failure((rocket::http::Status::Unauthorized, ()));
        }

        let client = request.guard::<&State>().await.succeeded()?;
        match fetch_user_by_id(client, &subject).await {
            Ok(user) => Outcome::Success(AuthenticatedUser { user_id: user.user_id }),
            Err(_) => Outcome::Failure((rocket::http::Status::Unauthorized, ())),
        }
    }
}

async fn fetch_user_by_id(client: &Client, user_id: &str) -> Result {
    let resp = client.get_item()
        .table_name("users")
        .key("user_id", aws_sdk_dynamodb::AttributeValue::S(user_id.to_string()))
        .send()
        .await?
        .item()
        .map(|item| User {
            user_id: item.get("user_id").and_then(|v| v.as_s().ok()).unwrap_or(&"").to_string(),
            email: item.get("email").and_then(|v| v.as_s().ok()).unwrap_or(&"").to_string(),
        })
        .ok_or_else(|| aws_sdk_dynamodb::error::SdkError::ResourceNotFound("User not found".into()))
}