Why Vendor Security Testing Matters (Even if It’s Not Required)
When people think about getting breached, they usually imagine something going wrong in their own systems.
But that’s not always how it happens.
Plenty of security incidents start with a third-party vendor. A scheduling tool, a chat plugin, a data enrichment API — something outside your direct control, but deeply integrated into your stack. And when they get compromised, it’s your users, your data, and your reputation on the line.
Just because a vendor has a sleek website and a SOC 2 badge doesn’t mean they’re secure — or even taking security seriously. The only way to know is to ask.
Vendors Can Get You Hacked
The attack surface doesn’t stop at your perimeter. Modern systems are connected to dozens of other platforms, and the weakest one often becomes the entry point.
That might be:
- An API integration that leaks more than it should
- A plugin or SDK with hidden behavior
- A backend vendor who never disabled a default password
Once an attacker gains access through a trusted third party, they can often move freely — bypassing your controls entirely.
Just Because It’s Not Required Doesn’t Mean It’s Optional
SOC 2, ISO 27001, and similar frameworks require vendor oversight — but not always actual technical testing.
That creates a gap. One that attackers are happy to exploit.
If a vendor has access to your data, infrastructure, or production environment, they should be able to show evidence of independent security testing — not just policies and paperwork.
What to Look for in Vendor Security Testing
Not all penetration testing is the same. If you’re vetting a vendor, here’s what to look for:
- A recent penetration test report, ideally within the last 12 months
- Manual testing, not just an automated vulnerability scan
- Web application, API, and infrastructure coverage — internal and external if applicable
- A clear methodology, like OWASP ASVS for apps or PTES for infrastructure
- Risk ratings with context, not just copy-pasted CVSS numbers
- Clear remediation guidance with steps to reproduce and verify fixes
Good vendors work with testers who go beyond checkbox compliance. They don’t hand over a scanner dump or a report that only serves their ego. They give you something your team can understand, prioritize, and act on.
If a vendor can’t explain what was tested or how, or refuses to share anything at all — that’s not a good sign.
Don’t Reward Vendors Who Can’t Prioritize Security
Security testing is one of the few ways to validate a vendor’s claims. If they handle sensitive data or connect deeply into your environment, it’s not unreasonable to expect them to prove they’re doing things right.
If they won’t invest in it, or if the results show a low-effort checkbox approach, you’re the one left holding the risk.
Final Thoughts
Vendor risk isn’t theoretical — it’s a common, documented cause of real-world breaches.
You can’t secure what you don’t control, but you can make better choices about who you rely on.
Ask for testing. Ask for proof. And work with vendors who care about security as much as you do.
Want help reviewing vendor test results — or running tests on a vendor system yourself? Let’s chat.
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