Bola Idor in Aspnet with Cockroachdb

Broken Object Level Authorization (BOLA) occurs when an API exposes object identifiers and fails to enforce that the authenticated subject is authorized to access a specific instance of a resource. In an ASP.NET application using CockroachDB, this risk is shaped by how identifiers are generated, how queries are constructed, and how claims are translated into database filters.

ASP.NET commonly uses route or query parameters such as id to locate resources. If those values are directly mapped to CockroachDB without an ownership or tenant check, an attacker can increment or guess IDs (e.g., /api/invoices/123 → /api/invoices/124) and retrieve or operate on records belonging to other users. CockroachDB, while providing strong consistency and SQL compatibility, does not inherently enforce row-level permissions; it executes the SQL you provide. Therefore, if the application constructs queries like SELECT * FROM invoices WHERE id = $1 using an attacker-controlled id, the database will return the row if it exists, regardless of business ownership.

A concrete scenario: an ASP.NET Core controller action receives an invoiceId from the route and builds a parameterized query against CockroachDB. If the developer omits a tenant or user identifier from the WHERE clause, the query becomes a horizontal privilege escalation path. Even with parameterization to prevent injection, the absence of a tenant filter means any valid invoice ID is accessible. This is a classic BOLA pattern, and it is exacerbated when IDs are predictable (e.g., sequential integers) or when internal object references inadvertently leak into the API surface (e.g., foreign keys exposed in JSON responses).

Additional risk arises from how CockroachDB handles secondary indexes and schema design. If your ASP.NET app uses an index on a column such as user_id but the query omits that column due to a coding gap, the database will still return rows that match the provided ID, making the authorization check appear successful while actually bypassing intended constraints. The application must therefore ensure that every CockroachDB query includes both the object identifier and the subject’s scope (tenant, organization, or user) explicitly.

Best-practice design in this context involves treating object IDs as opaque, enforcing authorization at the query layer, and avoiding reliance on client-supplied identifiers alone. ASP.NET middleware or service-layer checks should resolve the current user’s permissions and append tenant or user filters before the SQL is sent to CockroachDB. This disciplined separation of identification and authorization prevents BOLA across the API surface and aligns with OWASP API Top 10 A01:2023 broken object level authorization.

To mitigate BOLA in ASP.NET applications backed by CockroachDB, enforce tenant or user scoping at the data-access layer. Use parameterized SQL with explicit WHERE clauses that include ownership filters, and validate the caller’s relationship to the object before returning any data.

Example: a minimal API endpoint that safely retrieves an invoice only if it belongs to the authenticated user.

// Program.cs (ASP.NET Core minimal API)
var builder = WebApplication.CreateBuilder(args);
builder.Services.AddAuthentication(); // configure JWT or cookie auth
builder.Services.AddAuthorization();
builder.Services.AddNpgsql<AppDbContext>("Host=free-tier.aws-us-east1.cockroachlabs.cloud:26257;Database=invoices;SSL Mode=VerifyFull;Trust Server Certificate=true;Username=app_user;Password=**");
var app = builder.Build();
app.UseAuthentication();
app.UseAuthorization();

app.MapGet("/api/invoices/{id:guid}", async (Guid id, HttpContext context, AppDbContext db) =>
{
    var userId = context.User.FindFirst("sub")?.Value ?? throw new UnauthorizedAccessException();
    var invoice = await db.Invoices
        .Where(i => i.Id == id && i.OwnerId == userId)
        .SingleOrDefaultAsync();
    if (invoice is null)
    {
        return Results.NotFound();
    }
    return Results.Ok(invoice);
});
app.Run();

// AppDbContext and entity
public class AppDbContext : DbContext
{
    public AppDbContext(DbContextOptions<AppDbContext> options) : base(options) {}
    public DbSet<Invoice> Invoices => Set<Invoice>();
}
public class Invoice
{
    public Guid Id { get; set; }
    public string OwnerId { get; set; } = string.Empty;
    public decimal Amount { get; set; }
    public string Currency { get; set; } = string.Empty;
}

Key points: the query filters on both Id and OwnerId, ensuring that even if an attacker guesses a valid GUID, they cannot access invoices owned by another user. Use CockroachDB’s PostgreSQL wire protocol and a compatible .NET provider (e.g., Npgsql) to execute parameterized queries safely. Avoid string interpolation or concatenation to prevent accidental injection or privilege bypass.

For broader protection, implement a data-access guard that automatically applies tenant filters. In a multi-tenant setup, define a base repository that appends the current user’s scope to every query.

// TenantEnforcingRepository.cs
public class InvoiceRepository
{
    private readonly AppDbContext _db;
    private readonly IHttpContextAccessor _httpContextAccessor;
    public InvoiceRepository(AppDbContext db, IHttpContextAccessor httpContextAccessor)
    {
        _db = db;
        _httpContextAccessor = httpContextAccessor;
    }
    public async Task<Invoice?> GetOwnedInvoiceAsync(Guid id)
    {
        var userId = _httpContextAccessor.HttpContext?.User.FindFirst("sub")?.Value
            ?? throw new UnauthorizedAccessException("User not resolved");
        return await _db.Invoices
            .Where(i => i.Id == id && i.OwnerId == userId)
            .SingleOrDefaultAsync();
    }
    public async Task<List i.OwnerId == userId)
            .ToListAsync();
    }
}

Additionally, validate and normalize incoming identifiers. If your API accepts numeric or string IDs, ensure they are parsed safely and that no secondary lookup bypasses ownership checks. Combine these database-side filters with ASP.NET’s policy-based authorization to create defense-in-depth against BOLA.