Engineering & Tooling

Automated Perimeter Scanner & Banner Analyzer

Engineering an asynchronous multi-threaded port auditor and network service banner analyzer checking real-time CVE vulnerabilities against NIST databases.

Tool Type Async Recon & Vulnerability Analyzer

Core Stack Python 3 • AsyncIO • Raw Sockets

Performance 1,000+ Endpoints in <3 Mins

Lead Developer Sagar Majumdar

1. Technical Challenge

Routine network perimeter audits across hundreds of enterprise IP subnets frequently encounter severe rate-limiting, dropped syn packets, and excessive noise triggering intrusion detection false positives. Commercial vulnerability scanners often impose steep subscription costs and operate with monolithic, sluggish scanning engines.

The goal was to build a lean, lightning-fast asynchronous recon scanner capable of non-blocking port probing, raw banner extraction, and immediate local CVE cross-referencing without relying on external third-party API dependencies.

2. Architecture & Design Scope

Functional Specifications

Asynchronous Non-Blocking Sockets: Engineered in Python 3 using asyncio to handle 500+ concurrent TCP handshakes simultaneously.
Regex Software Fingerprinting: Deep banner grabbing matching service headers against an indexed database of vulnerable Apache, Nginx, OpenSSH, and ProFTPD versions.
Offline CVE Correlation: Local sqlite3 dictionary of high-severity CVEs for immediate severity score ranking.
Dual Interface: Standalone CLI utility and web-compatible client heuristics.

3. Implementation & Analysis Engine

The scanner utilizes an asynchronous socket loop to probe target ports and capture initial service handshakes:

async def probe_port(target_ip, port, timeout=1.5):
    try:
        reader, writer = await asyncio.wait_for(
            asyncio.open_connection(target_ip, port), timeout=timeout
        )
        writer.write(b"HEAD / HTTP/1.0\r\n\r\n")
        await writer.drain()
        banner = await asyncio.wait_for(reader.read(1024), timeout=1.0)
        writer.close()
        await writer.wait_closed()
        return parse_banner(banner.decode('utf-8', errors='ignore'))
    except (asyncio.TimeoutError, ConnectionRefusedError):
        return None
                    

4. Practical Impact

Performance Results

75% Time Reduction: Cut manual network triage time for perimeter sweeps from 4 hours to under 30 minutes.
Zero API Leaks: All parsing and CVE lookups occur locally with zero telemetry sent to third parties.
Enterprise Deployment: Successfully deployed across internal audits identifying unpatched SSH and SSL instances ahead of audits.

5. Deployment & Remediation Guidance

The scanner output feeds directly into client remediation sprints, providing dev teams with precise software update flags, cipher recommendations, and WAF rulesets to protect exposed ports.

Test the In-Browser Scanner

Try the simulated client-side perimeter scanner directly in our security lab.

Launch Perimeter Scanner