Race Condition in Adonisjs with Dynamodb

A race condition in AdonisJS when interacting with DynamoDB typically occurs when multiple concurrent requests read and write the same item without effective synchronization, leading to lost updates or inconsistent state. This often maps to the BOLA/IDOR and BFLA/Privilege Escalation checks that middleBrick runs in parallel, because the vulnerability surfaces when authorization checks and state transitions are not atomic.

Consider an order management API in AdonisJS where a handler reads an order’s current status from DynamoDB, checks permissions, and then writes an updated status. If two requests execute this flow concurrently, both may read the same pre-update status, each pass authorization, and then write conflicting updates. The last write wins, potentially allowing a lower-privileged action to overwrite a higher-privileged one or changing state in an unintended way (e.g., marking a canceled order as paid).

DynamoDB’s conditional writes are the primary mechanism to prevent this class of issue. Without a condition that validates the expected state before updating, concurrent operations are not serialized by the application layer. middleBrick’s checks for Property Authorization and Input Validation highlight these gaps by correlating runtime behavior with the OpenAPI spec and flagging missing conditions or overly permissive update endpoints.

In an unauthenticated or weakly authenticated context, an attacker can probe timing differences and invoke operations concurrently to test whether authorization and state checks are reliably enforced. The LLM/AI Security checks in middleBrick also look for patterns where AI-assisted tooling might inadvertently generate unsafe concurrency patterns (e.g., non-atomic multi-step updates) by inspecting system prompts and outputs for indicators of unsafe agent usage or exposed internal logic.

Example of a vulnerable AdonisJS handler (TypeScript):

import { HttpContextContract } from '@ioc:Adonis/Core/HttpContext'
import { DynamoDBClient, GetItemCommand, UpdateItemCommand } from '@aws-sdk/client-dynamodb'

export default class OrdersController {
  private readonly ddb = new DynamoDBClient({})

  public async updateStatus({ request, params }: HttpContextContract) {
    const orderId = params.id
    const { status } = request.body()

    // Vulnerable: read-modify-write without conditional write
    const getCmd = new GetItemCommand({
      TableName: 'orders',
      Key: { id: { S: orderId } }
    })
    const { Item } = await this.ddb.send(getCmd)
    if (!Item) { throw new Error('Not found') }

    // Authorization check may happen here (e.g., user === Item.userId)
    // But if two requests pass this check concurrently, both will write.

    const putCmd = new UpdateItemCommand({
      TableName: 'orders',
      Key: { id: { S: orderId } }
    })
    // Missing condition: expected status or version not enforced
    putCmd.input.UpdateExpression = 'SET #s = :newStatus'
    putCmd.input.ExpressionAttributeNames = { '#s': 'status' }
    putCmd.input.ExpressionAttributeValues = { ':newStatus': { S: status } }
    await this.ddb.send(putCmd)

    return { ok: true }
  }
}

An attacker could send many concurrent updateStatus requests with different statuses; without a conditional write, the final state may reflect an unauthorized transition. middleBrick’s BFLA/Privilege Escalation and BOLA/IDOR checks are designed to surface such authorization and identity-based concurrency risks.

Remediation centers on using DynamoDB conditional expressions to make state transitions atomic and to enforce invariants under concurrency. In AdonisJS, this means constructing UpdateItemCommand with a ConditionExpression that checks the current expected state (or version) before applying changes.

Use optimistic locking with an attribute like version (numeric) or compare status transitions explicitly. For example, allow a status change from pending to paid only if the current status is pending. This prevents one request’s update from being silently overwritten by another.

Example of a safe AdonisJS handler (TypeScript):

import { HttpContextContract } from '@ioc:Adonis/Core/HttpContext'
import { DynamoDBClient, GetItemCommand, UpdateItemCommand, ConditionalCheckFailedException } from '@aws-sdk/client-dynamodb'

export default class OrdersController {
  private readonly ddb = new DynamoDBClient({})

  public async updateStatus({ request, params }: HttpContextContract) {
    const orderId = params.id
    const { status } = request.body()

    // 1. Read current item (can be omitted if condition only needs known prior state)
    const getCmd = new GetItemCommand({
      TableName: 'orders',
      Key: { id: { S: orderId } },
      ConsistentRead: true
    })
    const { Item } = await this.ddb.send(getCmd)
    if (!Item) { throw new Error('Not found') }

    const currentStatus = Item.status?.S

    // 2. Enforce transition rules and concurrency safety via condition expression
    // Only allow transition from 'pending' to 'paid'. Adjust rules as needed.
    const conditionExp = 'attribute_exists(id) AND status = :expectedStatus'
    const updateCmd = new UpdateItemCommand({
      TableName: 'orders',
      Key: { id: { S: orderId } },
      UpdateExpression: 'SET #s = :newStatus',
      ConditionExpression: conditionExp,
      ExpressionAttributeNames: { '#s': 'status' },
      ExpressionAttributeValues: {
        ':newStatus': { S: status },
        ':expectedStatus': { S: currentStatus || 'missing' }
      }
    })

    try {
      await this.ddb.send(updateCmd)
    } catch (err: any) {
      if (err.name === 'ConditionalCheckFailedException') {
        // Conflict: current state does not match expected; fail safely
        throw new Error('Conflict: the record was modified concurrently')
      }
      throw err
    }

    return { ok: true }
  }
}

For stronger guarantees, add a numeric version attribute and increment it on each update using ADD #v :inc with a condition that the stored version matches the client-supplied version (optimistic locking). This pattern prevents lost updates even under high concurrency.
middleBrick’s scans will flag endpoints where updates lack conditions and map them to relevant compliance items (e.g., OWASP API Top 10:2023-B1). The Pro plan’s continuous monitoring can alert you when new findings appear, and the GitHub Action can fail builds if a scan detects missing conditions on state-changing endpoints.