Broken Access Control in Rocket with Dynamodb

Broken Access Control (BOLA/IDOR) in a Rocket application using DynamoDB typically occurs when authorization checks are missing or incorrectly applied before data access. Rocket routes often deserialize path or query parameters into handler arguments, and if the handler directly uses those values to form a DynamoDB request without validating that the authenticated subject is allowed to access the targeted item, an IDOR vulnerability arises.

Consider a route like GET /users/:user_id/profile. A naive implementation might extract user_id from the path and pass it to a DynamoDB GetItem or Query without confirming the caller owns that user_id. Because DynamoDB access patterns are often keyed by partition keys such as PK = USER#123, exposing or inferring the key structure can allow attackers to enumerate other users’ records by guessing IDs. If the service uses IAM credentials shared across application logic, over-permissive policies can compound the issue, allowing broader read/write access than intended.

Insecure direct object references become more likely when the API maps user input 1:1 to DynamoDB keys without an authorization layer. For example, an attacker could modify user_id in the URL or tamper with a JSON Web Token’s subject claim to access another user’s data. DynamoDB’s lack of native row-level semantics means developers must enforce access control in application code; missing this step results in BOLA/IDOR. Insecure configuration, such as permissive resource policies in DynamoDB Streams or Data Pipelines, can also expose data beyond the intended scope.

Using middleBrick’s LLM/AI Security checks is valuable here because prompt injection and jailbreak probes can uncover whether authorization logic is bypassed via crafted inputs that manipulate behavior. The scanner’s checks for SSRF and Unsafe Consumption are also relevant, as SSRF against DynamoDB metadata services can expose credentials, while unsafe consumption of user input can lead to malformed queries that bypass intended filters.

An OpenAPI/Swagger spec analysis can highlight endpoints with path parameters that map to DynamoDB keys without security schemes, reinforcing the need for explicit authorization. middleBrick’s scan testing the unauthenticated attack surface can flag endpoints where actions like PutItem or UpdateItem are reachable without proof of ownership, providing prioritized findings with severity and remediation guidance.

To remediate BOLA/IDOR in Rocket with DynamoDB, enforce ownership checks before constructing any request to DynamoDB. Use Rocket’s request guards to resolve the authenticated subject and compare it against the resource’s owning identifier derived from the path parameter.

Example secure handler in Rocket (Rust) using the AWS SDK for DynamoDB:

use aws_sdk_dynamodb::Client;
use rocket::get;
use rocket::serde::json::Json;

#[get("/users/:user_id/profile")]
async fn get_profile(
    user_id: String,
    auth: Auth<Claims>,
    client: &State<Client>,
) -> Result<Json<Profile>, Status> {
    // Ensure the authenticated user matches the requested user_id
    let claims = auth.into_inner().map_err(|_| Status::Unauthorized)?;
    if claims.sub != user_id {
        return Err(Status::Forbidden);
    }

    let pk = format!("USER#{}", user_id);
    let output = client
        .get_item()
        .table_name("AppUsers")
        .key("PK", aws_sdk_dynamodb::types::AttributeValue::S(pk))
        .send()
        .await
        .map_err(|_| Status::InternalServerError)?;

    let item = output.item().ok_or(Status::NotFound)?;
    let profile = Profile::try_from(item).map_err(|_| Status::InternalServerError)?;
    Ok(Json(profile))
}

This ensures the subject in the token (claims.sub) must equal the user_id path parameter before any DynamoDB call. The partition key is constructed locally and never echoed directly from user input, preventing IDOR via key manipulation.

Additional DynamoDB-specific mitigations include:

• Use condition expressions in PutItem or UpdateItem to assert ownership, e.g., attribute_exists(PK) AND PK = :expected_pk.
• Scope IAM policies for the application role to allow access only to items where PK = ${cognito-identity.amazonaws.com:sub} using policy variables, reducing impact of over-permissive roles.
• Validate and sanitize all inputs used in key expressions to avoid injection or malformed keys that could bypass intended filters.
• Enable DynamoDB Streams with care and ensure consumers enforce the same ownership checks, as streams can expose data change events.

middleBrick’s CLI tool (middlebrick scan <url>) can be integrated into testing to verify that endpoints correctly enforce authorization. The GitHub Action helps enforce a security score threshold in CI/CD pipelines, while the MCP Server allows scanning APIs directly from your AI coding assistant during development.