Your Legacy System is an ISO 27001 Failure Waiting to Happen

Your legacy tech stack is a black box. If you can’t document how data flows through your 15-year-old monolithic insurance platform or your COBOL-backed banking portal, you cannot achieve or maintain ISO 27001 compliance. Auditors don't care about "tribal knowledge" or the developer who retired three years ago; they care about Annex A controls, asset management, and secure system architecture.

The $3.6 trillion global technical debt isn't just a financial burden; it’s a compliance bottleneck. When 67% of legacy systems lack any meaningful documentation, the path to certification usually involves months of "software archaeology"—manual code reviews that cost 40 hours per screen and still miss critical edge cases.

The future of compliance isn't manual documentation. It’s understanding how visual reverse engineering transforms undocumented legacy chaos into a structured, compliant, and modern codebase in days rather than years.

TL;DR: Visual Reverse Engineering (VRE) automates the discovery of legacy system logic and data flows, accelerating ISO 27001 compliance by replacing manual "archaeology" with auto-generated documentation, API contracts, and secure React components.

The Compliance Gap: Why Legacy Systems Fail Audits#

ISO 27001:2022 requires rigorous documentation of information security controls. Legacy systems typically fail in three specific areas:

1. •A.8 Asset Management: You cannot protect what you don't know exists. Legacy systems often have "hidden" API endpoints and undocumented data processing layers.
2. •A.12 Operations Security: Without clear documentation, change management is guesswork. A "simple fix" in a legacy system often opens a massive security hole.
3. •A.14 System Acquisition, Development, and Maintenance: This requires "secure engineering principles." Most legacy systems were built before modern security patterns (like OIDC or JWT) were standard.

How Visual Reverse Engineering Works#

Visual Reverse Engineering (VRE) flips the traditional modernization script. Instead of reading millions of lines of spaghetti code, Replay records real user workflows. By capturing the DOM mutations, network calls, and state changes in real-time, Replay reconstructs the underlying business logic.

This "video as source of truth" approach ensures that the documentation matches the actual behavior of the system, not what a stale README file says from 2012.

From Black Box to Documented Codebase#

When you run a legacy workflow through Replay, the platform doesn't just record a video; it parses the execution. It identifies:

• •Data Inputs: Every form field, validation rule, and user entry point.
• •State Transitions: How the application moves from one logical state to another.
• •API Dependencies: Every "under the hood" call to legacy SOAP or REST services.

💰 ROI Insight: Manual reverse engineering averages 40 hours per screen. With Replay, this is reduced to 4 hours. For an enterprise application with 50 screens, that’s a saving of 1,800 engineering hours.

Mapping VRE to ISO 27001 Controls#

To understand how visual reverse engineering accelerates compliance, we must look at the specific Annex A controls.

1. Control A.14.2.1: Secure System Engineering Principles#

ISO 27001 requires that systems be built using secure engineering principles. Legacy systems often use insecure patterns (e.g., inline SQL, lack of CSRF tokens). Replay extracts the logic and regenerates it into modern React components that follow current security standards.

typescript
// Example: Replay-generated React component with built-in security patterns
// Original: Legacy ASP.NET form with insecure state handling
// Extracted & Modernized via Replay AI Automation Suite

import React from 'react';
import { useForm } from 'react-hook-form';
import { zodResolver } from '@hookform/resolvers/zod';
import * as z from 'zod';

// Replay automatically generates the schema based on recorded user inputs
const schema = z.object({
  accountNumber: z.string().min(10).max(12),
  routingNumber: z.string().length(9),
  transactionAmount: z.number().positive(),
});

export const SecureLegacyTransfer = () => {
  const { register, handleSubmit, errors } = useForm({
    resolver: zodResolver(schema)
  });

  const onSubmit = (data: z.infer<typeof schema>) => {
    // Replay identifies the legacy API endpoint and maps it to a secure proxy
    console.log("Submitting validated data to legacy bridge:", data);
  };

  return (
    <form onSubmit={handleSubmit(onSubmit)} className="p-4 bg-white rounded shadow">
      <label>Account Number</label>
      <input {...register("accountNumber")} className="border p-2" />
      {errors.accountNumber && <span>{errors.accountNumber.message}</span>}
      
      {/* Replay preserves the exact business logic of the legacy UI */}
      <button type="submit" className="bg-blue-600 text-white p-2 mt-4">
        Complete Transfer
      </button>
    </form>
  );
};

2. Control A.14.2.5: Secure System Architecture#

Auditors need to see a high-level architecture diagram that matches reality. Replay’s Flows feature automatically maps the architecture of your legacy system by observing the interaction between the frontend and backend.

💡 Pro Tip: Use Replay's "Flows" to identify "Shadow APIs"—endpoints that are being used by the frontend but aren't documented in your API gateway. These are major ISO 27001 non-conformities.

3. Control A.17.1.2: Implementing Information Security Continuity#

If your legacy system fails, how quickly can you rebuild it? Because Replay generates a Library of reusable components and Blueprints of system logic, your "Mean Time to Recovery" (MTTR) drops significantly. You aren't just backing up data; you are backing up the intelligence of the system.

The 5-Step Rapid Compliance Roadmap#

If you are facing an ISO 27001 audit in 6 months and have a legacy system with zero documentation, follow this workflow using Replay.

Step 1: Discovery & Recording#

Identify the "Crown Jewels"—the workflows that handle PII, PHI, or financial transactions. Use Replay to record these workflows. A single recording session captures the visual state, the network requests, and the data schema.

Step 2: Automated Technical Debt Audit#

Replay’s AI Automation Suite analyzes the recorded sessions to identify technical debt. It flags deprecated libraries, insecure API patterns, and redundant logic. This becomes your "Risk Treatment Plan" for ISO 27001.

Step 3: API Contract Generation#

Legacy systems often lack Swagger/OpenAPI specs. Replay generates these contracts automatically from the network traffic captured during the recording.

yaml
# Generated by Replay from Legacy Recording Session
openapi: 3.0.0
info:
  title: Legacy Insurance Claims API
  version: 1.0.0
paths:
  /api/v1/claims/submit:
    post:
      summary: Extracted from user workflow "Submit New Claim"
      responses:
        '200':
          description: Successful submission
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ClaimResponse'

Step 4: Component Extraction#

Using the Blueprints editor, extract the legacy UI into a modern React Design System. This ensures that the "new" version of your system is built on a clean, auditable foundation while maintaining 100% of the original business logic.

Step 5: E2E Test Generation#

ISO 27001 requires evidence of functional testing. Replay generates End-to-End (E2E) tests (Cypress/Playwright) directly from your recordings. This proves to auditors that the modernized system behaves exactly like the compliant legacy system.

⚠️ Warning: Do not attempt a "Big Bang" rewrite for compliance. 70% of these projects fail to meet their original timeline, leaving you with a half-finished system that is even harder to audit than the original.

Real-World Impact: Financial Services Case Study#

A Tier-1 bank was struggling to bring a 20-year-old commercial lending portal into compliance for an upcoming ISO 27001 audit. The system had over 200 screens and no living documentation.

• •Manual Estimate: 18 months and $2.4M for full documentation and modernization.
• •Replay Implementation: 12 weeks.
• •Outcome: Replay recorded the top 50 critical workflows, generated full API documentation, and extracted the core UI into a React-based Design System. The bank passed the audit with zero major non-conformities related to the legacy system.

📝 Note: Replay is built for regulated environments. It is SOC2 compliant, HIPAA-ready, and offers an On-Premise deployment model for organizations that cannot send data to the cloud.

Frequently Asked Questions#

How does Visual Reverse Engineering handle complex business logic?#

Replay doesn't just look at the UI; it monitors the data transformations that happen between the user's action and the server's response. By capturing the "before" and "after" state of every transaction, Replay’s AI can infer the business rules applied to the data, ensuring no logic is lost during extraction.

Does Replay require access to our legacy source code?#

No. Replay works by observing the application at runtime. This is particularly valuable for systems where the source code is lost, obfuscated, or written in languages that modern developers cannot easily read. It treats the legacy system as a "black box" and extracts the intelligence from its behavior.

How does this help with the "Continuous Improvement" requirement of ISO 27001?#

ISO 27001 isn't a "one and done" certification. It requires a PDCA (Plan-Do-Check-Act) cycle. Replay provides a living library of your system's flows. When the system changes, you simply record a new session to update your documentation and API contracts automatically, ensuring your compliance posture never degrades.

Can Replay handle PII during the recording process?#

Yes. Replay includes PII/PHI masking capabilities. You can define sensitive fields that should be redacted during the recording process, ensuring that no sensitive customer data leaves your secure environment or enters the Replay platform.

The Future Isn't Rewriting—It's Understanding#

The era of the "Big Bang Rewrite" is over. It’s too slow, too expensive, and too risky for the modern regulatory environment. To achieve ISO 27001 compliance, you don't need to start from scratch; you need to understand what you already have.

Visual Reverse Engineering provides the bridge from the undocumented past to the compliant future. By turning user workflows into documented codebases, Replay allows enterprise teams to modernize at the speed of business, not the speed of manual archaeology.

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Ready to modernize without rewriting? Book a pilot with Replay - see your legacy screen extracted live during the call.