Bola Idor in Actix with Dynamodb

Broken Object Level Authorization (BOLA) occurs when an API exposes references to objects (e.g., DynamoDB keys) and does not verify that the requesting identity is authorized to access that specific object. In an Actix-web service using DynamoDB as the persistence layer, BOLA typically arises when route parameters or query parameters are used directly as keys without validating the requester’s relationship to the resource.

Consider an endpoint like GET /users/{user_id}/profile. If the handler retrieves the item using the user_id from the path and returns it without confirming that the authenticated actor is that same user, an attacker can enumerate or access any user’s profile by changing the ID. Because DynamoDB stores items with primary keys such as PK and SK, a naive implementation might expose these values (or a deterministic derivative) in URLs or client-side tokens, making horizontal privilege escalation straightforward.

DynamoDB-specific factors that amplify BOLA in Actix include:

• Key design and exposure: If your application uses predictable keys (e.g., USER#123) and passes them to the client, an attacker can easily modify them. Even when keys are opaque (e.g., UUIDs), lack of ownership checks means any valid key can be accessed.
• Unauthenticated or insufficient authorization checks: Actix middleware may verify a token’s validity but skip verifying that the principal owns the requested DynamoDB item. Because scans test unauthenticated surfaces, an endpoint missing ownership validation will be flagged.
• Data model patterns: In DynamoDB, a single table design often uses composite keys to store multiple entity types. If an endpoint uses a global secondary index (GSI) or a sort key without ensuring the caller’s scope, horizontal BOLA occurs when one user can request another user’s sort key range.

Real-world analogs from the OWASP API Top 10 include excessive data exposure and broken access control. A scanner like middleBrick runs active tests to detect whether object identifiers are accepted from the client and whether authorization is enforced, surfacing BOLA before attackers do.

To remediate BOLA in an Actix service backed by DynamoDB, enforce ownership or scoped access checks on every request that references a DynamoDB key. Do not rely on client-supplied identifiers alone; derive keys from the authenticated principal and validate permissions server-side.

Example: a protected profile endpoint that ensures the caller can only access their own data.

use actix_web::{web, HttpResponse, Result};
use aws_sdk_dynamodb::Client;
use serde::Deserialize;

#[derive(Deserialize)]
struct PathId {
    user_id: String,
}

async fn get_profile(
    path: web::Path,
    user_identity: Option<actix_web_identity::Identity>, // authenticated principal
    dynamo: web::Data<Client>,
) -> Result<HttpResponse> {
    let requester_id = user_identity
        .ok_or_else(|| actix_web::error::ErrorUnauthorized("missing identity"))?
        .id(); // e.g., "USER#123"

    let target_id = path.user_id;
    if requester_id != target_id {
        return Ok(HttpResponse::Forbidden().body("access denied to this resource"));
    }

    let key = format!("USER#{}", target_id);
    let resp = dynamo
        .get_item()
        .table_name("AppTable")
        .key("PK", aws_sdk_dynamodb::types::AttributeValue::S(key.clone()))
        .key("SK", aws_sdk_dynamodb::types::AttributeValue::S(format!("PROFILE#{}", target_id)))
        .send()
        .await
        .map_err(|e| actix_web::error::ErrorInternalServerError(e.to_string()))?;

    let item = resp.item().ok_or_else(|| actix_web::error::ErrorNotFound("not found"))?;
    // map item to your domain type and return
    Ok(HttpResponse::Ok().json(item))
}

Key points in this fix:

• The authenticated identity (e.g., from cookies or a JWT) is used as the source of truth for ownership.
• The route parameter is compared against the authenticated principal before any DynamoDB call.
• Keys are constructed server-side; clients never send raw DynamoDB keys that can be tampered with.

Additional DynamoDB-specific practices:

• Use scoped GSIs: Design your table so that queries are constrained by the authenticated user’s partition key (e.g., PK = USER#<id>) to avoid cross-user scans.
• Avoid exposing raw keys: Do not return DynamoDB keys or GSIs in API responses that the client can use as references without ownership checks.
• Validate sort key ranges: When querying a sort key, ensure the query is bounded by the caller’s scope rather than accepting open-ended filters from the client.

By combining runtime authorization in Actix with a disciplined DynamoDB data model, you reduce the risk of both horizontal and vertical BOLA.