Internal Penetration Testing: Why Testing from the Inside Matters
Internal penetration testing starts once an attacker slips past your front door. It shows what damage they could do from inside your network, like a compromised laptop or disgruntled staffer.
Most breaches begin externally, but the real cost hits when hackers move sideways inside. I’ve run hundreds of these tests for Brisbane clients, and they always reveal gaps you didn’t see coming.
What is Penetration Testing?
Penetration testing, or pentesting, mimics real hackers to find weaknesses before they strike. Testers use the same tools and tricks cybercriminals do, but legally and with your permission.
It’s not just scanning for bugs. We actively try to exploit them, grab data, or escalate access, then hand you a roadmap to fix it all.
For Australian organisations, this ties straight into ASD’s Essential Eight, where testing validates your controls against realistic attacks.
Internal vs External Pentesting
External pentesting hits your public-facing stuff: websites, emails, VPNs. It assumes zero access, probing from the internet.
Internal pentesting flips that. We plug into your LAN, like via a staff VPN or endpoint, and test what happens next. Think lateral movement across servers or privilege jumps to admin rights.
You need both. External guards the gate; internal checks the rooms behind it. Skip internal, and one breached device turns into a full takeover.
Why Internal Testing Matters for Your Business
Hackers love insiders or pivots from external wins. Once inside, weak segmentation lets them roam freely.
Australia saw 36,700 cyber hotline calls in 2023-24, up 12%, with over 1,100 incidents reported. Many stemmed from internal flaws after initial entry.
Financial firms under APRA CPS 234 must test internal controls regularly. Privacy Act fines hit AUD 3.3 million for sloppy data handling.
It builds trust too. Clients sleep better knowing we’ve stress-tested their setup end-to-end.
Vulnerabilities Internal Tests Uncover
Poor network splits top the list. Flat networks mean one foothold equals everywhere.
Weak passwords and unpatched servers come next. Testers crack them fast, then escalate to domain control.
Custom apps and databases often leak sensitive info internally. Firewalls block outsiders but not insiders sniffing traffic.
In one Brisbane gig, we jumped from a user PC to their CRM in minutes via misconfigs. Fixed it, and they passed SOC 2 audit.
How to Prepare for Internal Penetration Testing
Start with scope. Pick networks, apps, or maturity levels to test. Share diagrams, IP ranges, and no-go zones upfront.
Run your own vuln scans first. Tools like Nessus flag easy wins; we validate exploits.
Set up test accounts with real user privileges. Notify your team so alerts don’t trigger panic.
Document controls: firewalls, MFA, patching schedules. Logs access helps us track without chaos.
If you’re not sure where to start, chat with us at Siege Cyber. Our gap analysis spots low-hanging fruit before full testing.
The Internal Pentest Process Step by Step
We kick off with planning: rules of engagement, timelines, goals.
Recon follows. Map your network, sniff services, hunt weak spots without noise.
Scan for vulns, then exploit. Escalate privileges, move laterally, grab mock data.
Report details findings: screenshots, risks rated high to low, fixes prioritised.
Remediation support optional. We retest post-fix to confirm.
Expect 1-4 weeks, depending on size. Costs scale with scope; check our pricing for internals.
Real Outcomes from Internal Tests
A Queensland MSP we tested had solid externals but porous internals. We pivoted to their backups in hours.
Post-fix, they hit Essential Eight maturity 3 and won bigger contracts.
Another client prepped for ISO 27001. Internal test proved their segmentation, speeding certification.
These aren’t hypotheticals. They’re why Aussie businesses call us.
Ready to test your internals? Visit our penetration testing page or check pricing at siegecyber.com.au/#pentest-pricing.
Siege Cyber has been helping businesses across Australia with penetration testing, compliance, and cyber risk for over 20 years. If you’d like to discuss what type of testing makes sense for your organisation, or if you’re preparing for an ISO 27001 or SOC 2 audit and need testing as part of that process, get in touch.
You can reach us at siegecyber.com.au or email [email protected] directly. We’re based in Brisbane but work with clients across the country.