EXTERNAL INFRASTRUCTURE PEN TESTING

CREST-Certified External Penetration Testing for UK Businesses

External network penetration testing and external infrastructure penetration testing aligned to PTES, NIST SP 800-115, the OWASP Testing Guide, and OSSTMM / SANS methodologies. Manual exploitation of exposed services, weak SSL/TLS, leaked credentials, subdomain takeover, and patch-level RCE. Fixed-price quotes within 24 hours.

CREST Member · Verify ↗
External Penetration Testing
PTES · NIST 800-115
Industry Methodology
OSINT · SHODAN · CENSYS
Attack-Surface Recon
CREST
Approved Provider
PTES
+ NIST SP 800-115
FREE
Retest Included
24h
Scope to Active Test
15min
is how long it takes an attacker to find your exposed RDP server on Shodan. External infrastructure pen testing finds it first.

Your attack surface is bigger than you think.

Modern UK businesses run a sprawling attack surface — and effective attack surface management requires more than passive scanning. Public IP ranges, forgotten subdomains, third-party hosting, leaked credentials on paste sites, exposed admin panels with default credentials, dev / staging environments left routable. External attackers don’t ask for an asset list — they enumerate it.

Our external infrastructure penetration testing combines OSINT (Shodan, Censys, theHarvester, dark-web credential scanning) with manual exploitation against every reachable service. Reports satisfy ISO 27001 Annex A.13.1, PCI DSS Req 11.3, NCSC vulnerability management guidance, and Cyber Essentials boundary firewalls — without translation work.

12 ATTACK CATEGORIES

What We Test in External Penetration Testing

Aligned to PTES, NIST SP 800-115, and the OWASP Testing Guide. Each category exploited manually with industry-standard tooling — Nmap, Burp Suite Pro, custom scripts, and OSINT platforms.

🌐

Exposed Services & Open Ports

Discovery and verification of every reachable port, banner-grabbing service identification, and version fingerprinting against the public IP range.

🔓

Outdated Software / Unpatched CVEs

Manual exploitation of unpatched services. Validated proof-of-concept rather than scanner false positives.

🔐

Weak SSL/TLS Configuration

Cipher suite analysis, certificate validation, downgrade attacks, expired certs, weak DH parameters, deprecated protocol versions.

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Credential Leakage & Defaults

Dark-web credential scans, paste-site hits, default-credential testing on every reachable management interface.

📡

Subdomain Takeover

Dangling DNS records pointing to deprovisioned cloud resources. Identification + safe proof-of-takeover via test record.

📨

Email Security (SPF/DKIM/DMARC)

Domain spoofing exposure, SPF/DKIM/DMARC validation, BIMI / MTA-STS posture, anti-phishing posture review.

🖥

VPN / RDP / SSH Exposure

Brute-force resilience, MFA enforcement, version exploits (e.g. CVE-2019-19781 Citrix), credential stuffing tolerance.

☁️

Cloud Edge Misconfiguration

Exposed S3 / Blob containers, leaked CloudFront origins, misconfigured WAFs, SaaS edge endpoints with weak auth.

⚙️

Web Admin Panels Exposed

phpMyAdmin, Jenkins, Kibana, GitLab, Grafana, Prometheus — discovered through hostname enumeration and brute-forced for default / weak credentials.

📊

Information Disclosure

Verbose error messages, exposed git repositories, .DS_Store, server-status, /metrics endpoints, robots.txt secrets.

📂

Forgotten Dev / Staging

Discovery of dev.*, staging.*, test.*, qa.*, uat.* subdomains routable from the public internet — typically with weaker controls than production.

🛡

Bypass of WAF / DDoS Edge

Origin IP exposure via SSL certificate logs, historical DNS, mail-server identification — bypass of CloudFlare / AWS Shield / Akamai protection.

FOUR-PHASE METHODOLOGY

External Penetration Testing — From OSINT to Attestation

Discovery before exploitation. External network penetration testing starts where attackers start — open-source recon. We never test what we don’t know. We never miss what’s reachable.

1

OSINT & Recon

Passive footprinting via Shodan, Censys, FOFA. Subdomain enumeration. Certificate transparency log mining. Dark-web credential scan. theHarvester for exposed addresses.
2

Active Discovery

Port scanning across the IP range. Service identification. Version fingerprinting. CVE matching. SSL/TLS configuration assessment. Subdomain DNS validation.
3

Manual Exploitation

CVE proof-of-exploit. Default credential testing. Attack surface management — old API versions, deprecated subdomains, exposed dev endpoints — confirmed against your live attack-surface inventory. Subdomain takeover validation. Information disclosure exploitation. Origin-IP bypass testing. Configuration weakness chains.
4

Report & Retest

CVSS-scored findings, attack-path narrative, executive + technical reports. Free retest within 30 days. Direct engineer access via portal.

Verified Accreditations Auditors Accept

Every accreditation independently issued by a recognised UK certification body. Click CREST to verify our membership.

COMPLIANCE READY

External Reports Mapped to Every Framework

Findings tagged to specific control IDs in your compliance framework. Audit teams submit directly without translation.

ISO 27001 (Annex A)

A.13.1 network security, A.13.2 information transfer, A.12.6.1 vulnerability management evidence.

PCI DSS

Req 11.3.1 / 11.3.2 external network testing — required for all PCI-scoped environments processing payment data.

Cyber Essentials Plus

Boundary firewall and external testing scope. Aligned with IASME audit-grade evidence requirements.

NCSC Vulnerability Management

External-facing assets validated against NCSC vulnerability management guidance — public-sector aligned.

SOC 2 Type I & II

CC7.1 vulnerability identification and CC6.6 logical access controls evidence for SOC 2 audits.

NHS DSPT & UK GDPR Art 32

External attack-surface evidence for NHS supply-chain partners and any regulated processor of UK personal data.

TRANSPARENT PRICING

Transparent External Penetration Testing Pricing

All tiers include the same depth of testing. Price varies by attack-surface complexity — number of public IPs, subdomain count, cloud edge breadth, and exposed services.

SMALL / SMB
£4,000 – £6,500
Depends on attack-surface size

1-20 public IPs, single subnet, ≤10 subdomains. Standard external posture review. Typically 2-3 day engagement.

  • Free retests included
  • Free rescheduling
  • No cancellation fees
  • 24-hour scope to active testing
  • Live findings to client portal
  • Executive + technical report
  • 60-min walkthrough call
  • Letter of attestation
MOST COMMISSIONED
GROWTH / MID-MARKET
£6,500 – £14,000
Depends on attack-surface size

20-100 IPs, multi-subnet, cloud edge, ≤50 subdomains, mixed VPN / RDP / SaaS exposure. Typically 5-7 day engagement.

  • Free retests included
  • Free rescheduling
  • No cancellation fees
  • 24-hour scope to active testing
  • Live findings to client portal
  • Executive + technical report
  • 60-min walkthrough call
  • Letter of attestation
ENTERPRISE
£14,000+
Depends on attack-surface size

100+ IPs, hybrid cloud, multi-region, 50+ subdomains, regulated workloads, Cyber Essentials Plus scope. Typically 8-12 day engagement.

  • Free retests included
  • Free rescheduling
  • No cancellation fees
  • 24-hour scope to active testing
  • Live findings to client portal
  • Executive + technical report
  • 60-min walkthrough call
  • Letter of attestation

What You Actually Get

Five things that distinguish our external testing from automated scans and box-tick competitors.

🎯

What You Get From External Penetration Testing

OSINT-driven attack-surface discovery, manual exploitation of every reachable service, and free retests until validated.
🔭

Discovery-First Methodology

We start with PASSIVE recon. Shodan / Censys / certificate-transparency mining. We test what attackers actually find — not your asset list.
🔍

No Scanner-Only Reports

Every CVE flagged on automated scanners is manually validated. False positives are eliminated before reporting. You get real risk, not noise.
🛡

Boundary Firewall + Cyber Essentials Aligned

External pen testing maps directly to Cyber Essentials Plus boundary scope and IASME audit-grade evidence.
🇬🇧

UK CREST + IASME + ISO 27001 + ISO 9001

Independently accredited. Verifiable on the CREST marketplace. Reports accepted by FCA, NCSC, NHS, ICO, SOC 2 auditors, and cyber insurers.

Frequently Asked

How long does an external penetration test take?

A small external engagement (1-20 IPs, ≤10 subdomains) typically takes 2-3 working days. Mid-market (20-100 IPs, cloud edge) takes 5-7 days. Enterprise (100+ IPs, multi-region, hybrid cloud) takes 8-12 days. Test duration is determined during scoping based on attack-surface size.

How much does external infrastructure penetration testing cost in the UK?

Small engagements range £4,000-£6,500. Mid-market (most commonly commissioned) £6,500-£14,000. Enterprise £14,000+. All quotes are fixed-price after scoping. Day rate equivalent is £1,000-£1,500 per CREST-certified tester per day.

What methodology do you follow?

We follow PTES (Penetration Testing Execution Standard), NIST SP 800-115, and the OWASP Testing Guide. Each engagement starts with passive OSINT before any active testing. We test exactly what’s reachable from the public internet — what an external attacker would actually see. Combined with internal network penetration testing, you get full attack-path coverage.

Do you use Shodan, Censys, and OSINT tools?

Yes. Shodan, Censys, FOFA, theHarvester, and certificate transparency log mining are core to our recon phase. We also perform dark-web credential exposure checks for your domain and key personnel. OSINT is included in every external engagement at no additional cost.

Do you check for subdomain takeover?

Yes — every external engagement checks for dangling DNS records pointing to deprovisioned cloud resources. Subdomain takeover is a common high-impact finding (e.g., GitHub Pages / Heroku / S3 / Azure CDN). We provide safe proof-of-takeover evidence without claiming the resource.

Can you test our cloud edge (AWS / Azure / GCP)?

Yes — external testing covers cloud edge surface: load balancers, public S3 / Blob containers, exposed CloudFront origins, lambda function URLs, VPC peering misconfiguration. For full configuration review of cloud control planes we recommend our dedicated AWS, Azure, or GCP cloud security review.

What’s the difference between external and internal pen testing?

External network penetration testing simulates an attacker with no access — they only see your public-facing services. Internal testing simulates an attacker who’s already on your network (compromised laptop, malicious insider, post-phish foothold). They’re complementary; CREST and NCSC recommend both annually for high-assurance organisations.

Do you provide evidence for Cyber Essentials Plus?

Yes — external pen testing maps directly to Cyber Essentials Plus boundary firewall and external scanning scope. We provide the test report, attestation letter, and remediation evidence in the format IASME assessors require. We are an IASME Cyber Essentials Certifying Body ourselves.

Will testing impact production?

External network penetration testing is largely passive at first (banner-grabbing, version detection, OSINT). Active exploitation phases use safe-by-default checks. Any potentially disruptive test (exploit attempts on rare services) is paused for explicit client approval before execution. We do not run DoS attacks against production.

Do you test from the UK or internationally?

Testing originates from controlled test infrastructure in the UK or EU by default. We can rotate source addresses for scenarios where an attacker would use specific geo origins (Russia, China, etc.) — but only when this matches your real threat model and has been explicitly authorised.

Are your testers UK-based and what certifications do they hold?

All external infrastructure testers are vetted UK or international engineers. Relevant certifications across the team include CREST CRT and CCT INF (infrastructure), OSCP, OSCE, and protocol-specific specialisms. SC-cleared testers are available for public-sector and regulated-financial engagements.

Do you sign NDAs?

Yes. Standard NDA before any technical detail is shared, and we operate under a project-specific master agreement that includes data handling, deliverable IP, and breach notification clauses. Custom MSAs and AUP terms are accepted for enterprise and public-sector clients.

READY TO SCOPE

Book an External Pen Test Scoping Call

30 minutes with a CREST-certified infrastructure tester. Fixed-price quote within 24 hours. No sales pipeline.