Cybersecurity for startups: what you need to know before scaling

By the QuantumSec team

Founding a startup is hard enough without having to think about security. But ignoring it has very concrete consequences: a breach can sink you before your Series A, an enterprise client can block your most important contract, or a due diligence review can reveal security debt that tanks your valuation. This guide explains, without sugarcoating it, what a tech startup needs to know about security.

When to run your first pentest

The short answer: before your first enterprise client or your first fundraising round. The long answer: it depends what you're handling. If your product processes personal, financial or health data, you need a security assessment before public launch. If you're a B2B SaaS, your first enterprise client will ask for a pentest report or a security questionnaire. If you're going through a Series A, security due diligence is practically standard.

Security due diligence: what investors ask for

In Series A rounds and beyond, investors or their technical advisors review the startup's security posture. What they typically ask for: a recent pentest report (less than 12 months old), a documented security policy, vulnerability management (how do you prioritize and remediate?), access management and MFA, and an incident response plan. You don't need ISO 27001 at Series A, but you do need to show you think about security.

How to win enterprise contracts with security

Enterprise clients (banking, insurance, utilities, large retailers) have security teams that will evaluate their vendors. They'll ask you to complete a security questionnaire (CAIQ, SIG or a proprietary one), to provide evidence of an annual pentest, to have a vulnerability management policy, and in some cases, ISO 27001 or SOC 2 certification. Every "no" on that questionnaire adds friction to the sales process.

The risk of AI-generated code in startups

Many startups today build their MVPs with tools like GitHub Copilot, Cursor or ChatGPT. It's a real competitive advantage in speed, but it introduces specific security risks: AI-generated code reproduces insecure patterns from its training data, developers who don't understand the code can't identify vulnerabilities, and dependencies suggested by the AI can be outdated or compromised. An audit of AI-generated code before launch can save you from a serious incident.

FAQ

How much does a first pentest cost for a startup?

For a mid-sized web application (SaaS MVP), a grey-box pentest including the API usually runs between €2,000 and €5,000. Startup-specific plans with more accessible pricing exist. The ROI is immediate if it unlocks an enterprise contract or a funding round.

Do I need ISO 27001 to sell to large companies?

ISO 27001 is the most recognized certification, but it isn't always required. Many enterprise clients accept a pentest report plus documented security policies as sufficient evidence. ISO 27001 is usually a formal requirement in heavily regulated sectors (banking, public health) or for significant contract sizes.