Unknown systems
Development or test environments left online
Adversary Simulation
Perimeter Assessment
Identify exposed assets, reduce your attack surface, and uncover potential entry points through comprehensive perimeter assessments.
Discuss an engagement- Objective
- Reduce external exposure
- Maturity
- Large, distributed estates
- Approach
- Manual, expert-driven
- Result
- Mapped attack surface
Securing your external attack surface
The external perimeter is often the first point of contact for adversaries seeking to infiltrate your organisation. Misconfigured systems, forgotten development environments, and exposed services can provide attackers with direct paths to internal networks.
SilentGrid's Perimeter Assessment maps Internet-facing assets across your organisation and tests them for exploitable weaknesses. The assessment is manual and expert-driven, covering vulnerabilities automated tools miss in custom-built applications and exposures that depend on your industry's processes and systems.
Researchers investigate logic flaws, business process vulnerabilities, and exposures in third-party software not covered by mainstream security research, alongside known CVEs. Asset discovery checks for external systems that have escaped the organisation's inventory, reducing the risk of unintended exposure.
Depending on the time allocated and your budget, the exercise can simulate an opportunistic attacker looking for easy targets or a targeted attack against your organisation with specific objectives.
The growing external attack surface
Cloud platforms, third-party services and global infrastructure can make external assets difficult to track. A perimeter assessment checks for these exposures:
Shadow IT
Unmonitored systems spun up outside official processes
Legacy exposure
Forgotten or unpatched systems presenting vulnerabilities
Third-party risks
Exposed integrations and cloud service misconfigurations
Is perimeter assessment the right fit?
The assessment looks inward from the internet, so it answers what is exposed and reachable rather than what an intruder could do afterwards. Where the perimeter is already well understood, assumed breach testing picks up from the foothold onwards.
Perimeter assessments are ideal for organisations that
- Operate large, distributed or cloud-integrated infrastructures
- Require visibility into forgotten or unmonitored Internet-facing assets
- Are preparing for regulatory audits or compliance reviews
- Need to reduce external attack surfaces as part of broader security initiatives
Our methodology
SilentGrid combines reconnaissance, threat intelligence and active testing to map your external attack surface. Researchers manually validate exploitability and pursue attack paths that depend on the context of your environment.
- 01
Passive reconnaissance
- OSINT, DNS enumeration, and internet-wide scans to identify exposed assets without direct interaction
- 02
Active enumeration
- Probing for misconfigurations in public-facing services, web applications, and network devices
- 03
Vulnerability identification
- Detecting known vulnerabilities, outdated software, and misconfigured service implementations
- 04
Targeted exploitation
- Time-boxed validation of exploitability including credential stuffing and weak configurations
Run it continuously
Map the perimeter once, or test it all year.
A single perimeter assessment maps what is exposed to the internet and which entry points an attacker could use. Where new services go online faster than an annual assessment can track, CAOS (Continuous Adversary Operations Service) keeps attacking internet-facing services and identity through the year.
Explore CAOSDeliverables and reporting
Perimeter assessment reporting records the assets found, exploitable entry points and remediation priorities:
Comprehensive asset inventory
Full list of identified Internet-facing assets, subdomains, and third-party systems
Risk prioritisation
Vulnerabilities ranked by severity, exploitability, and potential business impact
Attack surface analysis
Visual mapping of external entry points, open ports, and exposed APIs
Remediation guidance
Clear, practical steps to harden exposed services and mitigate risk
Continuous perimeter monitoring
The external attack surface changes as new services are deployed and cloud resources are created, while forgotten systems remain exposed. SilentGrid's continuous perimeter monitoring combines asset discovery with manual assessment.
Researchers assess the perimeter manually, using tools to track current CVEs. They investigate third-party software and exposures that depend on your processes, industry and attack surface. Each assessment builds on their knowledge of the environment, allowing them to pursue attack vectors automated scanning misses.
Our continuous monitoring program includes
Monthly asset discovery
To identify new exposures and shadow IT
Scheduled vulnerability assessments
Flexible frequency to catch emerging threats and misconfigurations
Real-time alerts
When critical exposures are detected
Beyond the assessment: strengthening defences
Perimeter findings identify where further testing would be useful, from exposed applications to the internal paths an attacker could follow after gaining access:
Red team operations
Full-scope adversary simulation across technology, people and response processes
Assumed breach
Test internal defences once an external foothold is established
Social engineering
Test human defences against phishing and pretexting attacks
Web application testing
Focus on critical web applications to uncover application-level vulnerabilities
Why SilentGrid
SilentGrid's consultants are hand-picked, and between them they have delivered red team engagements globally over decades, including CBEST for UK financial institutions and CORIE engagements in Australia. Their sector experience covers banking and financial services, insurance, government, critical infrastructure and healthcare.
Consultants find 0-day vulnerabilities in commercial software and speak or teach at security conferences. That research produces the custom tooling used to bypass EDR and network controls, and keeps techniques current with the threat actor being simulated. The methodology follows concepts set out in NIST, OWASP, PTES and OSSTMM.
CREST ANZApproved company Individual credentials across our team include
- OSEE
- OSCE3
- OSED
- OSEP
- OSWE
- GXPN
- CRTO
- CRTE
- CRTP
- OSCP
What that looks like in practice
Human intelligence
Expert researchers who understand context, business logic, and industry-specific risks
Beyond CVE scanning
Discover vulnerabilities in custom applications and obscure third-party software
Adaptive methodology
Each assessment builds on previous findings, uncovering deeper attack vectors
Global experience
Assessed perimeters across diverse industries and regions
Australian excellence
External security assessment experience in Australia
Expert team
Seasoned professionals with offensive security backgrounds
Trial by Internet
Who tries to knock on your server's door(s)…
Common questions
What is a perimeter assessment?
A perimeter assessment tests an organisation's internet-facing footprint the way an external attacker would: it maps exposed assets, including forgotten development systems, shadow IT and third-party services, then validates which are exploitable through manual, time-boxed testing. Depending on the time and budget allocated, it can simulate an opportunistic attacker or a targeted attack with specific objectives.
How is this different from an automated vulnerability scan?
The assessment is fundamentally manual and expert-driven. Security researchers go beyond known CVEs to uncover logic flaws, business process vulnerabilities and exposures in third-party software that mainstream security research has not covered.
What is in scope?
Internet-facing assets across the organisation, including subdomains, third-party systems, open ports and exposed APIs. Assets are identified through passive reconnaissance first, then probed through active enumeration.
How long does an assessment take?
One to six weeks, depending on the size of the external estate and the depth agreed for the exercise.
Can you simulate a particular kind of attacker?
Yes. Depending on the time allocated and your budget, the exercise can simulate an opportunistic attacker looking for easy targets, or a targeted attack against your organisation with specific objectives.
Do you exploit what you find?
Exploitation is time-boxed and used to validate exploitability, including credential stuffing and weak configurations, so that reported findings are demonstrated rather than assumed.
What does continuous monitoring add?
Monthly asset discovery to identify new exposures and shadow IT, scheduled vulnerability assessments at a frequency that suits you, and real-time alerts when critical exposures are detected. It maintains continuous visibility of the external attack surface, catches exposures before attackers find them, tracks posture improvements over time and supports external compliance requirements.
What do we receive at the end?
A comprehensive inventory of Internet-facing assets, subdomains and third-party systems, vulnerabilities ranked by severity, exploitability and business impact, a visual attack surface analysis, and practical remediation guidance.
Secure your perimeter
Get started with perimeter assessment
Discover and secure your external attack surface
SilentGrid identifies exposed assets and provides guidance to reduce your organisation's external risk.