Insecure Design in Koa with Cockroachdb

Insecure design in a Koa application using CockroachDB often stems from treating the database as a trusted boundary and failing to enforce authorization and validation close to the data. Koa’s lightweight middleware model encourages small, composable handlers, but without explicit checks this can lead to BOLA/IDOR and privilege escalation when route parameters are mapped directly to database identifiers. For example, a route like /api/users/:userId/profile that constructs a CockroachDB query by concatenating the path parameter into SQL without verifying that the authenticated actor owns that user ID allows horizontal privilege escalation across user boundaries.

CockroachDB’s SQL compatibility means common patterns such as dynamic query building and ORM usage can inadvertently expose unsafe consumption issues if inputs are not rigorously validated. An insecure design might concatenate user input into SQL strings or rely on generic parameter mappers without scoping by tenant or actor. This becomes critical in multi-tenant scenarios where a missing tenant_id filter allows a request to read or modify data belonging to other tenants stored in the same CockroachDB cluster. The database will execute the query and return results, but the application logic incorrectly interprets the response as safe because it assumes the database enforces isolation, which it does not when queries are not scoped correctly.

Another insecure pattern is missing property authorization at the handler level. A Koa route that updates user settings might accept JSON with arbitrary keys and forward them as a CockroachDB UPSERT without validating which fields are mutable by the current role. This can lead to privilege escalation via BFLA if an attacker changes fields like is_admin or billing_role. Because CockroachDB returns success on malformed or over-permissive writes, the application may report success while the backend silently applies unintended changes. Input validation must be explicit and role-aware before any SQL is built, rather than relying on database constraints alone.

SSRF and unsafe consumption also emerge when Koa handlers dynamically build CockroachDB connection strings or use external URLs as identifiers without validation. If an attacker can influence a hostname or path that becomes part of a CockroachDB SQL string or a follow-up internal request, they can pivot to internal services or force the database to reach unexpected endpoints. The design should treat all external inputs as hostile and validate or encode them before they touch SQL strings or configuration used by the database client.

Finally, LLM/AI security interacts with insecure design when model-generated code or prompts are stored in CockroachDB and later rendered in Koa responses without output scanning. If prompts containing system instructions or API keys are saved via an unvalidated handler and then echoed back through an LLM endpoint, the system prompt leakage and data exfiltration risks increase. Securing the design requires treating database-stored content as untrusted output and applying the same validation and scanning that applies to any user input.

Remediation centers on scoping every database action to the actor and enforcing strict validation before constructing SQL. Use parameterised statements with placeholders and bind variables so CockroachDB treats values strictly as data. In Koa, create a helper that builds queries with tenant and user context explicitly included, avoiding string concatenation for identifiers or values.

// Secure Koa handler with CockroachDB (using node-postgres)
const { Pool } = require('pg');
const pool = new Pool({ connectionString: process.env.DATABASE_URL });

async function getUserProfile(ctx) {
  const userId = parseInt(ctx.params.userId, 10);
  const actorId = parseInt(ctx.state.user.id, 10);

  if (isNaN(userId) || isNaN(actorId)) {
    ctx.status = 400;
    ctx.body = { error: 'Invalid identifier' };
    return;
  }

  const query = {
    text: 'SELECT id, display_name, email FROM user_profiles WHERE id = $1 AND tenant_id = (SELECT tenant_id FROM users WHERE id = $2)',
    values: [userId, actorId],
  };

  const result = await pool.query(query);
  if (result.rows.length === 0) {
    ctx.status = 404;
    ctx.body = { error: 'Not found' };
    return;
  }
  ctx.body = result.rows[0];
}

This pattern ensures that the CockroachDB query is scoped by both the requested resource and the authenticated actor’s tenant, preventing BOLA/IDOR across users and tenants. Note the use of positional placeholders ($1, $2) to avoid injection and the explicit check that the actor’s tenant matches the row’s tenant.

For updates, validate each field against the role and use typed parameters rather than dynamic object spreading. Avoid forwarding raw JSON keys directly into SQL. Instead, whitelist mutable fields per role and bind each value individually.

// Secure update with role-aware property authorization
const allowedFieldsByRole = {
  user: ['display_name', 'email'],
  admin: ['display_name', 'email', 'billing_role'],
};

async function updateUserSettings(ctx) {
  const userId = parseInt(ctx.params.userId, 10);
  const actorId = parseInt(ctx.state.user.id, 10);
  const body = ctx.request.body;

  const role = ctx.state.user.role; // 'user' or 'admin'
  const allowed = allowedFieldsByRole[role] || [];
  const updates = Object.keys(body).filter((k) => allowed.includes(k));

  if (!updates.length) {
    ctx.status = 400;
    ctx.body = { error: 'No valid fields to update' };
    return;
  }

  const setClause = updates.map((_, i) => `${updates[i]} = $${i + 3}`).join(', ');
  const values = [
    userId,
    actorId,
    ...updates.map((k) => body[k]),
  ];

  const query = {
    text: `UPDATE user_profiles SET ${setClause} WHERE id = $1 AND tenant_id = (SELECT tenant_id FROM users WHERE id = $2) RETURNING id`,
    values,
  };

  const result = await pool.query(query);
  if (result.rowCount === 0) {
    ctx.status = 404;
    ctx.body = { error: 'Not found' };
    return;
  }
  ctx.body = result.rows[0];
}

For tenant isolation in CockroachDB, always include tenant_id in WHERE clauses and enforce it at the connection level when possible via session variables or application-level routing. Validate and normalize URLs and external identifiers before using them in SQL strings or constructing connection parameters to mitigate SSRF and unsafe consumption risks. Treat LLM-stored content as untrusted and apply output scanning before any inclusion in responses to prevent system prompt leakage or code execution via generated payloads.

middleBrick can support this secure design by scanning your Koa endpoints and CockroachDB interaction patterns to detect missing authorization, unsafe consumption, and LLM exposure risks. Use the CLI (middlebrick scan <url>) or GitHub Action to integrate checks into CI/CD and track scores over time with the Web Dashboard, ensuring insecure design patterns are caught before deployment.