kausthubh-coder/convex-security-audit

Convex Security Audit

Comprehensive security review patterns for Convex applications including authorization logic, data access boundaries, action isolation, rate limiting, and protecting sensitive operations.

Documentation Sources

Before implementing, do not assume; fetch the latest documentation:

• Primary: https://docs.convex.dev/auth/functions-auth
• Production Security: https://docs.convex.dev/production
• For broader context: https://docs.convex.dev/llms.txt

Instructions

Security Audit Areas

1. Authorization Logic - Who can do what
2. Data Access Boundaries - What data users can see
3. Action Isolation - Protecting external API calls
4. Rate Limiting - Preventing abuse
5. Sensitive Operations - Protecting critical functions

Authorization Logic Audit

Role-Based Access Control (RBAC)

// convex/lib/auth.ts
import { QueryCtx, MutationCtx } from "./_generated/server";
import { ConvexError } from "convex/values";
import { Doc } from "./_generated/dataModel";

type UserRole = "user" | "moderator" | "admin" | "superadmin";

const roleHierarchy: Record<UserRole, number> = {
  user: 0,
  moderator: 1,
  admin: 2,
  superadmin: 3,
};

export async function getUser(ctx: QueryCtx | MutationCtx): Promise<Doc<"users"> | null> {
  const identity = await ctx.auth.getUserIdentity();
  if (!identity) return null;
  
  return await ctx.db
    .query("users")
    .withIndex("by_tokenIdentifier", (q) => 
      q.eq("tokenIdentifier", identity.tokenIdentifier)
    )
    .unique();
}

export async function requireRole(
  ctx: QueryCtx | MutationCtx, 
  minRole: UserRole
): Promise<Doc<"users">> {
  const user = await getUser(ctx);
  
  if (!user) {
    throw new ConvexError({
      code: "UNAUTHENTICATED",
      message: "Authentication required",
    });
  }
  
  const userRoleLevel = roleHierarchy[user.role as UserRole] ?? 0;
  const requiredLevel = roleHierarchy[minRole];
  
  if (userRoleLevel < requiredLevel) {
    throw new ConvexError({
      code: "FORBIDDEN",
      message: `Role '${minRole}' or higher required`,
    });
  }
  
  return user;
}

// Permission-based check
type Permission = "read:users" | "write:users" | "delete:users" | "admin:system";

const rolePermissions: Record<UserRole, Permission[]> = {
  user: ["read:users"],
  moderator: ["read:users", "write:users"],
  admin: ["read:users", "write:users", "delete:users"],
  superadmin: ["read:users", "write:users", "delete:users", "admin:system"],
};

export async function requirePermission(
  ctx: QueryCtx | MutationCtx,
  permission: Permission
): Promise<Doc<"users">> {
  const user = await getUser(ctx);
  
  if (!user) {
    throw new ConvexError({ code: "UNAUTHENTICATED", message: "Authentication required" });
  }
  
  const userRole = user.role as UserRole;
  const permissions = rolePermissions[userRole] ?? [];
  
  if (!permissions.includes(permission)) {
    throw new ConvexError({
      code: "FORBIDDEN",
      message: `Permission '${permission}' required`,
    });
  }
  
  return user;
}

Data Access Boundaries Audit

// convex/data.ts
import { query, mutation } from "./_generated/server";
import { v } from "convex/values";
import { getUser, requireRole } from "./lib/auth";
import { ConvexError } from "convex/values";

// Audit: Users can only see their own data
export const getMyData = query({
  args: {},
  returns: v.array(v.object({
    _id: v.id("userData"),
    content: v.string(),
  })),
  handler: async (ctx) => {
    const user = await getUser(ctx);
    if (!user) return [];
    
    // SECURITY: Filter by userId
    return await ctx.db
      .query("userData")
      .withIndex("by_user", (q) => q.eq("userId", user._id))
      .collect();
  },
});

// Audit: Verify ownership before returning sensitive data
export const getSensitiveItem = query({
  args: { itemId: v.id("sensitiveItems") },
  returns: v.union(v.object({
    _id: v.id("sensitiveItems"),
    secret: v.string(),
  }), v.null()),
  handler: async (ctx, args) => {
    const user = await getUser(ctx);
    if (!user) return null;
    
    const item = await ctx.db.get(args.itemId);
    
    // SECURITY: Verify ownership
    if (!item || item.ownerId !== user._id) {
      return null; // Don't reveal if item exists
    }
    
    return item;
  },
});

// Audit: Shared resources with access list
export const getSharedDocument = query({
  args: { docId: v.id("documents") },
  returns: v.union(v.object({
    _id: v.id("documents"),
    content: v.string(),
    accessLevel: v.string(),
  }), v.null()),
  handler: async (ctx, args) => {
    const user = await getUser(ctx);
    const doc = await ctx.db.get(args.docId);
    
    if (!doc) return null;
    
    // Public documents
    if (doc.visibility === "public") {
      return { ...doc, accessLevel: "public" };
    }
    
    // Must be authenticated for non-public
    if (!user) return null;
    
    // Owner has full access
    if (doc.ownerId === user._id) {
      return { ...doc, accessLevel: "owner" };
    }
    
    // Check shared access
    const access = await ctx.db
      .query("documentAccess")
      .withIndex("by_doc_and_user", (q) => 
        q.eq("documentId", args.docId).eq("userId", user._id)
      )
      .unique();
    
    if (!access) return null;
    
    return { ...doc, accessLevel: access.level };
  },
});

Action Isolation Audit

// convex/actions.ts
"use node";

import { action, internalAction } from "./_generated/server";
import { v } from "convex/values";
import { api, internal } from "./_generated/api";
import { ConvexError } from "convex/values";

// SECURITY: Never expose API keys in responses
export const callExternalAPI = action({
  args: { query: v.string() },
  returns: v.object({ result: v.string() }),
  handler: async (ctx, args) => {
    // Verify user is authenticated
    const identity = await ctx.auth.getUserIdentity();
    if (!identity) {
      throw new ConvexError("Authentication required");
    }
    
    // Get API key from environment (not hardcoded)
    const apiKey = process.env.EXTERNAL_API_KEY;
    if (!apiKey) {
      throw new Error("API key not configured");
    }
    
    // Log usage for audit trail
    await ctx.runMutation(internal.audit.logAPICall, {
      userId: identity.tokenIdentifier,
      endpoint: "external-api",
      timestamp: Date.now(),
    });
    
    const response = await fetch("https://api.example.com/query", {
      method: "POST",
      headers: {
        "Authorization": `Bearer ${apiKey}`,
        "Content-Type": "application/json",
      },
      body: JSON.stringify({ query: args.query }),
    });
    
    if (!response.ok) {
      // Don't expose external API error details
      throw new ConvexError("External service unavailable");
    }
    
    const data = await response.json();
    
    // Sanitize response before returning
    return { result: sanitizeResponse(data) };
  },
});

// Internal action - not exposed to clients
export const _processPayment = internalAction({
  args: {
    userId: v.id("users"),
    amount: v.number(),
    paymentMethodId: v.string(),
  },
  returns: v.object({ success: v.boolean(), transactionId: v.optional(v.string()) }),
  handler: async (ctx, args) => {
    const stripeKey = process.env.STRIPE_SECRET_KEY;
    
    // Process payment with Stripe
    // This should NEVER be exposed as a public action
    
    return { success: true, transactionId: "txn_xxx" };
  },
});

Rate Limiting Audit

// convex/rateLimit.ts
import { mutation, query } from "./_generated/server";
import { v } from "convex/values";
import { ConvexError } from "convex/values";

const RATE_LIMITS = {
  message: { requests: 10, windowMs: 60000 }, // 10 per minute
  upload: { requests: 5, windowMs: 300000 },  // 5 per 5 minutes
  api: { requests: 100, windowMs: 3600000 },  // 100 per hour
};

export const checkRateLimit = mutation({
  args: {
    userId: v.string(),
    action: v.union(v.literal("message"), v.literal("upload"), v.literal("api")),
  },
  returns: v.object({ allowed: v.boolean(), retryAfter: v.optional(v.number()) }),
  handler: async (ctx, args) => {
    const limit = RATE_LIMITS[args.action];
    const now = Date.now();
    const windowStart = now - limit.windowMs;
    
    // Count requests in window
    const requests = await ctx.db
      .query("rateLimits")
      .withIndex("by_user_and_action", (q) => 
        q.eq("userId", args.userId).eq("action", args.action)
      )
      .filter((q) => q.gt(q.field("timestamp"), windowStart))
      .collect();
    
    if (requests.length >= limit.requests) {
      const oldestRequest = requests[0];
      const retryAfter = oldestRequest.timestamp + limit.windowMs - now;
      
      return { allowed: false, retryAfter };
    }
    
    // Record this request
    await ctx.db.insert("rateLimits", {
      userId: args.userId,
      action: args.action,
      timestamp: now,
    });
    
    return { allowed: true };
  },
});

// Use in mutations
export const sendMessage = mutation({
  args: { content: v.string() },
  returns: v.id("messages"),
  handler: async (ctx, args) => {
    const identity = await ctx.auth.getUserIdentity();
    if (!identity) throw new ConvexError("Authentication required");
    
    // Check rate limit
    const rateCheck = await checkRateLimit(ctx, {
      userId: identity.tokenIdentifier,
      action: "message",
    });
    
    if (!rateCheck.allowed) {
      throw new ConvexError({
        code: "RATE_LIMITED",
        message: `Too many requests. Try again in ${Math.ceil(rateCheck.retryAfter! / 1000)} seconds`,
      });
    }
    
    return await ctx.db.insert("messages", {
      content: args.content,
      authorId: identity.tokenIdentifier,
      createdAt: Date.now(),
    });
  },
});

Sensitive Operations Protection

// convex/admin.ts
import { mutation, internalMutation } from "./_generated/server";
import { v } from "convex/values";
import { requireRole, requirePermission } from "./lib/auth";
import { internal } from "./_generated/api";

// Two-factor confirmation for dangerous operations
export const deleteAllUserData = mutation({
  args: {
    userId: v.id("users"),
    confirmationCode: v.string(),
  },
  returns: v.null(),
  handler: async (ctx, args) => {
    // Require superadmin
    const admin = await requireRole(ctx, "superadmin");
    
    // Verify confirmation code
    const confirmation = await ctx.db
      .query("confirmations")
      .withIndex("by_admin_and_code", (q) => 
        q.eq("adminId", admin._id).eq("code", args.confirmationCode)
      )
      .filter((q) => q.gt(q.field("expiresAt"), Date.now()))
      .unique();
    
    if (!confirmation || confirmation.action !== "delete_user_data") {
      throw new ConvexError("Invalid or expired confirmation code");
    }
    
    // Delete confirmation to prevent reuse
    await ctx.db.delete(confirmation._id);
    
    // Schedule deletion (don't do it inline)
    await ctx.scheduler.runAfter(0, internal.admin._performDeletion, {
      userId: args.userId,
      requestedBy: admin._id,
    });
    
    // Audit log
    await ctx.db.insert("auditLogs", {
      action: "delete_user_data",
      targetUserId: args.userId,
      performedBy: admin._id,
      timestamp: Date.now(),
    });
    
    return null;
  },
});

// Generate confirmation code for sensitive action
export const requestDeletionConfirmation = mutation({
  args: { userId: v.id("users") },
  returns: v.string(),
  handler: async (ctx, args) => {
    const admin = await requireRole(ctx, "superadmin");
    
    const code = generateSecureCode();
    
    await ctx.db.insert("confirmations", {
      adminId: admin._id,
      code,
      action: "delete_user_data",
      targetUserId: args.userId,
      expiresAt: Date.now() + 5 * 60 * 1000, // 5 minutes
    });
    
    // In production, send code via secure channel (email, SMS)
    return code;
  },
});

Examples

Complete Audit Trail System

// convex/audit.ts
import { mutation, query, internalMutation } from "./_generated/server";
import { v } from "convex/values";
import { getUser, requireRole } from "./lib/auth";

const auditEventValidator = v.object({
  _id: v.id("auditLogs"),
  _creationTime: v.number(),
  action: v.string(),
  userId: v.optional(v.string()),
  resourceType: v.string(),
  resourceId: v.string(),
  details: v.optional(v.any()),
  ipAddress: v.optional(v.string()),
  timestamp: v.number(),
});

// Internal: Log audit event
export const logEvent = internalMutation({
  args: {
    action: v.string(),
    userId: v.optional(v.string()),
    resourceType: v.string(),
    resourceId: v.string(),
    details: v.optional(v.any()),
  },
  returns: v.id("auditLogs"),
  handler: async (ctx, args) => {
    return await ctx.db.insert("auditLogs", {
      ...args,
      timestamp: Date.now(),
    });
  },
});

// Admin: View audit logs
export const getAuditLogs = query({
  args: {
    resourceType: v.optional(v.string()),
    userId: v.optional(v.string()),
    limit: v.optional(v.number()),
  },
  returns: v.array(auditEventValidator),
  handler: async (ctx, args) => {
    await requireRole(ctx, "admin");
    
    let query = ctx.db.query("auditLogs");
    
    if (args.resourceType) {
      query = query.withIndex("by_resource_type", (q) => 
        q.eq("resourceType", args.resourceType)
      );
    }
    
    return await query
      .order("desc")
      .take(args.limit ?? 100);
  },
});

Best Practices

• Never run npx convex deploy unless explicitly instructed
• Never run any git commands unless explicitly instructed
• Implement defense in depth (multiple security layers)
• Log all sensitive operations for audit trails
• Use confirmation codes for destructive actions
• Rate limit all user-facing endpoints
• Never expose internal API keys or errors
• Review access patterns regularly

Common Pitfalls

1. Single point of failure - Implement multiple auth checks
2. Missing audit logs - Log all sensitive operations
3. Trusting client data - Always validate server-side
4. Exposing error details - Sanitize error messages
5. No rate limiting - Always implement rate limits

References

• Convex Documentation: https://docs.convex.dev/
• Convex LLMs.txt: https://docs.convex.dev/llms.txt
• Functions Auth: https://docs.convex.dev/auth/functions-auth
• Production Security: https://docs.convex.dev/production