Poodle Attack in Fiber with Cockroachdb

The Poodle (Padding Oracle On Downgraded Legacy Encryption) attack targets systems that negotiate TLS with fallback to SSLv3. When a server supports SSLv3, an attacker can force oracles via error messages returned for invalid padding, gradually decrypting secure communications. In a setup using the Fiber web framework with Cockroachdb as the backend datastore, the vulnerability arises if TLS configuration in Fiber permits protocol fallback and the application does not uniformly reject SSLv3 connections. Cockroachdb, when exposed via an API layer implemented in Fiber, may serve data over TLS; if the TLS settings allow SSLv3, an attacker positioned on the network can exploit the padding oracle to decrypt or manipulate traffic between the client and the Fiber service.

Specifically, this combination creates risk when:

• Fiber is configured with a TLS certificate but does not explicitly disable SSLv3, allowing clients to negotiate the weak protocol.
• Cockroachdb connections from Fiber use TLS with options that do not enforce modern cipher suites, making protocol downgrade feasible.
• The application relies on error messages from Cockroachdb or TLS stack to reveal padding validity, enabling adaptive oracle queries.

For example, if a developer sets up Fiber with a certificate and connects to Cockroachdb using a driver that does not restrict protocols, an attacker can intercept and modify ciphertext, sending crafted requests that cause different error responses depending on padding correctness. This can lead to session cookie theft or manipulation of database queries that are inadvertently exposed through error handling in Fiber routes.

Consider a Fiber route that queries Cockroachdb based on user-supplied identifiers without proper input validation and returns detailed database errors. An attacker can use these responses as an oracle to perform Poodle decryption. The presence of Cockroachdb does not directly introduce the weakness, but the integration can amplify the impact if errors are surfaced or if TLS negotiation is not hardened.

To detect this during a scan, middleBrick checks whether SSLv3 is offered and whether error messages vary based on padding validity, providing findings mapped to the TLS configuration and input validation checks.

Remediation focuses on disabling SSLv3 in TLS configuration, enforcing strong cipher suites, and ensuring that error handling does not expose padding-related information. When using Cockroachdb with Fiber, configure the database client and TLS settings explicitly to prevent fallback to insecure protocols.

First, ensure your Fiber TLS configuration disables SSLv3 and restricts to modern protocols. Using the tls.Config from the standard library, set MinVersion to tls.VersionTLS12 or higher:

import (
    "crypto/tls"
    "github.com/gofiber/fiber/v2"
    "github.com/gofiber/fiber/v2/middleware/tls"
)

func main() {
    cfg := &tls.Config{
        MinVersion: tls.VersionTLS12,
        CipherSuites: []uint16{
            tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
            tls.TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384,
        },
    }
    app := fiber.New()
    app.Use(tls.New(tls.Config{cert: tlsCfg}))
    // routes and database setup below
}

Second, configure the Cockroachdb connection string or driver options to enforce secure TLS settings. For example, using the Cockroachdb Go driver, specify ?sslmode=verify-full and provide root certificates to prevent insecure negotiation:

import (
    "database/sql"
    _ "github.com/cockroachdb/cockroach-go/v2/crdb"
    "github.com/jackc/pgx/v5/stdlib"
)

func setupDB() (*sql.DB, error) {
    connStr := "postgresql://root@localhost:26257/defaultdb?sslmode=verify-full&sslrootcert=root.crt"
    db, err := sql.Open("pgx", connStr)
    if err != nil {
        return nil, err
    }
    if err := db.Ping(); err != nil {
        return nil, err
    }
    return db, nil
}

Third, harden Fiber route error handling to avoid leaking padding or database details. Return generic error responses and log specifics server-side:

app.Get("/user/:id", func(c *fiber.Ctx) error {
    id := c.Params("id")
    var name string
    err := db.QueryRow("SELECT name FROM users WHERE id = $1", id).Scan(&name)
    if err != nil {
        c.Set("Content-Type", "application/json")
        return c.Status(fiber.StatusInternalServerError).JSON(fiber.Map{"error": "request failed"})
    }
    return c.JSON(fiber.Map{"name": name})
})

These steps reduce the attack surface by eliminating protocol downgrade opportunities and ensuring that errors do not serve as oracles for Poodle-style attacks. middleBrick can validate these configurations by scanning the endpoint and confirming that SSLv3 is not offered and that findings are mapped to TLS and input validation categories.