Bola Idor in Buffalo with Cockroachdb

BOLA (Broken Level of Authorization) and IDOR (Insecure Direct Object References) manifest distinctly when a Buffalo application uses CockroachDB as the backend. In Buffalo, routing patterns often map HTTP verbs and parameters directly to database identifiers. If an endpoint such as /accounts/:id uses a CockroachDB SQL query that interpolates :id without verifying that the authenticated subject owns that record, IDOR becomes reachable. The combination is risky because CockroachDB, like PostgreSQL, returns rows based on SQL predicates; if the predicate is constructed from user-supplied parameters without proper ownership checks, an attacker can modify or retrieve any row by guessing or enumerating identifiers.

Consider a Buffalo handler that retrieves an account using a raw SQL string without validating the current user’s relationship to the account:

// handlers/account.go
func AccountShow(c buffalo.Context) error {
    id := c.Params().Get("id")
    var account Account
    // BOLA/IDOR risk: no check that current_user owns this account
    if err := c.Connection().QueryRowxContext(c.Request().Context(), "SELECT id, user_id, balance FROM accounts WHERE id = $1", id).StructScan(&account); err != nil {
        return c.Error(404, err)
    }
    return c.Render(200, r.JSON(account))
}

In this example, id is taken directly from the URL. An attacker can change :id to access accounts belonging to other users. Because CockroachDB enforces SQL-level constraints, the query will succeed as long as the row exists, leaking or allowing modification of unauthorized data. The vulnerability is not CockroachDB-specific per se, but CockroachDB’s strict SQL semantics mean that an incorrect predicate reliably returns data or no data, making the impact deterministic. Authentication in Buffalo may set a user session, but if the handler does not join or filter by the authenticated user’s ID (e.g., WHERE id = $1 AND user_id = $2), the authorization boundary is missing. This is BOLA: the application exposes a direct object reference and lacks a proper authorization check at the function level, which in Buffalo is typically the handler or a service it calls.

Additionally, if the same pattern appears in list endpoints, such as fetching a user’s invoices via /users/:user_id/invoices, an attacker can tamper with user_id to enumerate other users’ invoices. Cockroachdb’s predictable key ranges can make enumeration efficient. Proper mitigation in Buffalo requires tying each data access to the current subject, using session or token claims to derive the user identifier, and ensuring SQL predicates incorporate that subject explicitly.

Remediation centers on ensuring every SQL query in Buffalo includes the authenticated subject as a mandatory filter. Below are concrete, working CockroachDB examples for Buffalo handlers.

1. Parameterized query with ownership check

Always join or filter by the subject derived from authentication (e.g., from session or JWT claims).

// handlers/account_safe.go
func AccountShowSafe(c buffalo.Context) error {
    id := c.Params().Get("id")
    userID := c.Value("user_id") // assume set by authentication middleware

    var account Account
    // Safe: ownership enforced in SQL
    if err := c.Connection().QueryRowxContext(c.Request().Context(),
        "SELECT id, user_id, balance FROM accounts WHERE id = $1 AND user_id = $2", id, userID).StructScan(&account); err != nil {
        if errors.Is(err, sql.ErrNoRows) {
            return c.Error(404, errors.New("not found or unauthorized"))
        }
        return c.Error(500, err)
    }
    return c.Render(200, r.JSON(account))
}

2. Use database-level constraints and prepared statements

CockroachDB supports prepared statements and can enforce row-level security if tables are set up accordingly. In Buffalo, use c.Connection().Preparex or rely on QueryRowx/Select with bound parameters to avoid injection and ensure stable plans.

// services/account_service.go
func GetAccountByOwner(db *gorm.DB, userID, accountID string) (*Account, error) {
    var account Account
    // Using GORM with CockroachDB; ensure indexes on (user_id, id)
    if err := db.Where("id = ? AND user_id = ?", accountID, userID).First(&account).Error; err != nil {
        return nil, err
    }
    return &account, nil
}

In raw SQL with CockroachDB, prefer $1, $2 placeholders. Avoid string concatenation or Sprintf to build identifiers; if dynamic table or column names are unavoidable, use pq.Identifier-like escaping via CockroachDB’s quote_ident or equivalent library functions, and validate against a strict allowlist.

3. List endpoints: scope by subject

For endpoints that list collections, scope the query to the authenticated user.

// handlers/invoice_index.go
func InvoiceIndex(c buffalo.Context) error {
    userID := c.Value("user_id")
    var invoices []Invoice
    // CockroachDB will use index on (user_id, id) for efficient seek
    if err := c.Connection().SelectContext(c.Request().Context(), &invoices,
        "SELECT id, amount, currency FROM invoices WHERE user_id = $1 ORDER BY created_at DESC", userID); err != nil {
        return c.Error(500, err)
    }
    return c.Render(200, r.JSON(invoices))
}

4. Middleware to enforce subject binding

Buffalo middleware can inject the user identifier into the context so handlers remain consistent.

// app/middleware/authentication.go
func Authentication(next buffalo.Handler) buffalo.Handler {
    return func(c buffalo.Context) error {
        token := extractToken(c)
        claims, err := parseClaims(token)
        if err != nil {
            return c.Unauthorized()
        }
        c.Set("user_id", claims.Subject)
        return next(c)
    }
}

5. Schema and index guidance for CockroachDB

Create indexes that support the ownership filters used in queries. For the accounts table, an index on (user_id, id) ensures efficient seek and prevents full scans that could expose data via timing differences.

-- CockroachDB SQL to create supporting index
CREATE INDEX idx_accounts_user_id_id ON accounts (user_id, id);

These fixes ensure that BOLA/IDOR is mitigated at the query layer, leveraging CockroachDB’s strengths while keeping authorization checks explicit in Buffalo handlers.