Network penetration testing evaluates the security of your organisation's network infrastructure by simulating attacks against internal and external network assets. External network pen testing targets internet-facing systems including firewalls, VPN gateways, mail servers, DNS servers, and web servers to identify vulnerabilities that could allow an attacker to gain initial access.
Internal network pen testing simulates an attacker who has already gained a foothold inside the network, testing for lateral movement opportunities, privilege escalation paths, misconfigured services, weak credentials, and unpatched systems. Testers use tools and techniques similar to those used by real adversaries, including port scanning, service enumeration, vulnerability exploitation, and credential attacks.
Network pen testing is critical for organisations of all sizes and is required by compliance frameworks including PCI DSS, NIST CSF, ISO 27001, and Cyber Essentials. Regular testing helps organisations understand their actual security posture and prioritise remediation efforts based on real risk.
UK offensive security consultancy delivering CREST-accredited penetration testing, adversary simulation and CBEST, TIBER-EU and TBEST threat-led testing, mainly for financial services and other large organisations.
Penetration testing firm trusted by nine of the top ten US banks, with the Resolve platform for continuous attack surface management.
Global enterprise cybersecurity consultancy founded in 1999 in Oxford, holding rare CREST STAR-FS accreditation and delivering penetration testing, red and purple teaming, and PCI QSA services across five international offices.
Munich- and Budapest-based embedded cybersecurity experts focused on financial services, automotive and mobility, manufacturing and industrial automation, energy and more. The services and platform go beyond compliance, supporting the requirements of the Cyber Resilience Act, PCI PTS, UN R155, ISO/SAE 21434 and other standards and regulations.
US penetration testing firm founded in 2011, running 600+ engagements a year with a fully remote, US-based team. Manual, expert-led testing across web, network, cloud, mobile, wireless, OT/ICS, and AI/LLM. Gartner Sample Vendor for PTaaS.
Global Big Four professional services firm delivering CREST, CHECK, and CBEST-accredited penetration testing and red teaming services from London, serving the UK's largest enterprises and regulated organisations.
CREST and CHECK-accredited UK penetration testing and managed security provider formed in 2026 from Pentest People, Bulletproof, and Target Defense, with CREST STAR/TLPT-FS capability and the GuardNest vulnerability management platform.
Elite UK offensive security consultancy specialising in CBEST/STAR/TIBER red teaming, advanced adversary simulation, and CREST-accredited penetration testing for FTSE 100 clients.
Full-service London-based cybersecurity consultancy with CREST, CHECK, and NCSC accreditations delivering offensive testing, managed detection, and strategic advisory services.
Global managed security provider with the elite SpiderLabs penetration testing team and deep PCI DSS compliance expertise.
Manchester-based independent cybersecurity consultancy with over 20 years of experience delivering CREST and CHECK-accredited penetration testing, red teaming, and compliance certification services.
CREST and CHECK-accredited UK penetration testing consultancy with CBEST approval, specialising in infrastructure, application, and simulated attack assessments across the public and private sectors.
External testing targets internet-facing systems to find ways an attacker could breach the perimeter. Internal testing simulates an attacker already inside the network, testing for lateral movement and privilege escalation.
Professional penetration testers take precautions to avoid service disruption. Testing is typically scheduled during agreed windows and testers avoid denial-of-service attacks unless specifically requested and authorised.
For external testing, provide IP ranges and domains in scope. For internal testing, provide network access (VPN or on-site), IP ranges, and any systems to exclude. Clear scoping and rules of engagement should be agreed in advance.