Privilege Escalation in Gin with Cockroachdb

Privilege Escalation in a Gin application using CockroachDB typically arises when role or permission checks are performed only in the application layer without enforcing them at the database level. Gin, as an HTTP framework, handles routing and request context, but if authorization logic relies solely on in-memory checks or incomplete parameter validation, an authenticated or unauthenticated attacker can manipulate requests to perform actions beyond their intended scope.

In this stack, a common pattern is to store user roles and permissions in CockroachDB and cache them in memory for performance. If these cached values are not re-validated on each request or if SQL queries are constructed by string concatenation rather than using parameterized statements and row-level security, attackers can exploit IDOR (Insecure Direct Object Reference) or BOLA (Broken Object Level Authorization) to access or modify other users' data or escalate privileges.

CockroachDB’s SQL semantics support role-based access control via roles and GRANT/REVOKE statements. However, if the Gin application connects to CockroachDB with a highly privileged account (for example, to simplify query building) and does not enforce per-user permissions in SQL, the application layer becomes the sole gatekeeper. A vulnerability in the Gin middleware or handler can therefore lead to direct privilege escalation, where an attacker gains access to administrative operations by tampering with identifiers or tokens.

Real-world attack patterns include modifying path parameters (e.g., changing userID in /users/{userID}/promote) or injecting crafted JWT claims to impersonate an admin. Since CockroachDB is compatible with PostgreSQL wire protocol, common SQL injection techniques can also be leveraged if queries are not properly parameterized, enabling attackers to bypass intended restrictions and execute statements with elevated privileges.

Additionally, if the Gin application uses shared database connections or pooled clients without proper tenant isolation, a misconfiguration can allow one user’s queries to run under another user’s context. This is especially risky when using CockroachDB’s secondary indexes and interleaved tables without validating tenant boundaries in every query. Proper use of row-level security policies and role-based access checks in SQL, combined with strict context validation in Gin handlers, is essential to mitigate these risks.

To remediate privilege escalation in Gin with CockroachDB, implement strict parameter validation, use prepared statements, and enforce role-based checks both in application logic and database permissions. Below are concrete, secure coding examples.

1. Use parameterized queries to prevent SQL injection

Always use placeholders instead of string concatenation when building SQL statements. This prevents attackers from injecting additional SQL commands.

// Correct: parameterized query in Gin handler using database/sql
package handlers

import (
    "database/sql"
    "net/http"
    "strconv"

    "github.com/gin-gonic/gin"
)

func promoteUser(db *sql.DB) gin.HandlerFunc {
    return func(c *gin.Context) {
        userID, err := strconv.Atoi(c.Param("userID"))
        if err != nil {
            c.JSON(http.StatusBadRequest, gin.H{"error": "invalid user ID"})
            return
        }
        // Use parameterized query to prevent injection
        result, err := db.ExecContext(c, "UPDATE users SET role = $1 WHERE id = $2", "admin", userID)
        if err != nil {
            c.JSON(http.StatusInternalServerError, gin.H{"error": "failed to update"})
            return
        }
        rowsAffected, _ := result.RowsAffected()
        if rowsAffected == 0 {
            c.JSON(http.StatusForbidden, gin.H{"error": "not allowed"})
            return
        }
        c.JSON(http.StatusOK, gin.H{"status": "promoted"})
    }
}

2. Enforce row-level security with CockroachDB roles

Define roles in CockroachDB and use them to restrict data access at the SQL level. The Gin application should connect with a role that has least privilege and rely on database policies to enforce tenant boundaries.

-- CockroachDB SQL: create roles and apply row-level security
-- Create roles
CREATE ROLE admin_role;
CREATE ROLE user_role;

-- Grant minimal privileges
GRANT SELECT, UPDATE ON users TO user_role;
GRANT ALL ON users TO admin_role;

-- Example table with tenant isolation using tenant_id
CREATE TABLE users (
    id INT PRIMARY KEY,
    tenant_id UUID NOT NULL,
    role STRING,
    data JSONB
);

-- Policy: users can only see their own tenant unless admin
-- (Implement tenant filtering in SQL; CockroachDB supports tenant isolation via secondary indexes)

In Gin, ensure each query includes tenant_id validation:

// Gin handler with tenant-aware query
type User struct {
    ID        int    `json:"id"`
    TenantID  string `json:"tenant_id"`
    Role      string `json:"role"`
}

func getUsers(c *gin.Context) {
    tenant := c.MustGet("tenant").(string)
    rows, err := db.QueryContext(c, "SELECT id, role FROM users WHERE tenant_id = $1", tenant)
    if err != nil {
        c.JSON(http.StatusInternalServerError, gin.H{"error": "db error"})
        return
    }
    defer rows.Close()
    var users []User
    for rows.Next() {
        var u User
        if err := rows.Scan(&u.ID, &u.Role); err != nil {
            c.JSON(http.StatusInternalServerError, gin.H{"error": "scan error"})
            return
        }
        users = append(users, u)
    }
    c.JSON(http.StatusOK, users)
}

3. Validate and re-check roles on each request

Do not rely on cached role values. Re-fetch or re-validate permissions in sensitive endpoints, and use middleware to enforce context consistency.

// Gin middleware to validate role per request
func AuthMiddleware() gin.HandlerFunc {
    return func(c *gin.Context) {
        userID := c.MustGet("user_id").(int)
        var role string
        err := db.QueryRowContext(c, "SELECT role FROM users WHERE id = $1", userID).Scan(&role)
        if err != nil {
            c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{"error": "invalid token"})
            return
        }
        c.Set("role", role)
        c.Next()
    }
}

Combine these practices to ensure that privilege escalation attempts are blocked by both application logic and database-enforced policies.