At most software companies between $50M and $300M, CTO security responsibilities include owning the entire security function by default. It’s not in the job description. Nobody announced it. But when the board asks about risk posture or a prospect sends over a security questionnaire, every head in the room turns to the same person. Security is a technology problem.

We’ve watched this play out at dozens of companies. The CTO absorbs security because there’s nobody else technical enough to do it. What starts as answering a few vendor questionnaires turns into managing pen tests, reviewing SOC 2 controls, and explaining threat models to the board. Somewhere along the way, you realize you’re doing two jobs, and not doing either one as well as you’d like.

The Three Things You Need to Get Right

The mistake most CTOs make is trying to learn security deeply. Reading NIST frameworks cover to cover. Taking CISSP study courses on weekends. Going down rabbit holes on container security or zero-trust architecture.

You don’t need to become a security expert. You need to know three things.

Start with knowing what to measure. You need a short list of metrics that tell you whether your security posture is improving or degrading. Patch cadence, mean time to remediate critical vulnerabilities, percentage of systems covered by EDR, and the status of your compliance certifications. That’s roughly it. If those numbers are moving in the right direction, you’re probably okay. If they’re not, you know where to focus.

Then there’s knowing what to delegate. Pen testing, compliance evidence gathering, vendor risk assessments, and security awareness training are all things that don’t require your direct involvement. They require your oversight. Find people, whether internal engineers with security interest or external partners, who can own the execution. Don’t think you can do 24/7 monitoring yourself — you can’t. Hire an expert service to be on the front lines. Your job is reviewing results and making decisions, not running Burp Suite yourself.

The hardest one, and the one most CTOs get wrong, is knowing when to hand it off. More on that below.

The “Good Enough” Phase and Its Limits

There’s a window where the CTO-as-CISO model works. Usually it’s when the company has fewer than 200 employees, one or two products, a relatively simple infrastructure, and compliance requirements that haven’t yet gotten aggressive. During this phase, a technically strong CTO with the right advisors can keep the security program moving forward.

We worked with a SaaS company with about $80M in revenue. The CTO had been handling security for three years. He’d gotten them through SOC 2 Type II, managed their pen test program, and built reasonable access controls. It was working. The metrics looked fine.

Then they landed an enterprise deal that required HITRUST certification. A major prospect wanted evidence of a formal risk management program with board-level reporting. The sales team needed security reviews turned around in 48 hours. The CTO was suddenly spending 15 hours a week on security, and his engineering roadmap was slipping.

That’s the pattern. The CTO-as-CISO model doesn’t fail gradually. It fails all at once when the business hits a growth inflection and security demands spike alongside it.

Recognizing the Handoff Point

Most CTOs recognize they need a dedicated security leader about 12 months after the need was already urgent. The delay is understandable. Hiring a CISO is expensive. The CTO has context that’s hard to transfer. And when you’ve been managing security yourself, it’s difficult to see the gaps because you’re too close to it.

There are signals that the handoff point has arrived.

Security work is displacing engineering leadership time by more than 10 hours per week. Customer security reviews are creating sales bottlenecks. Your compliance scope is expanding beyond your current certifications. You’re reacting to security issues rather than running a proactive program. Questions about security are getting more specific and harder to answer confidently.

If three or more of those are true, you’ve probably passed the point where a CTO can effectively own security part-time.

The handoff doesn’t have to be a full-time CISO hire on day one. A fractional CISO can bridge the gap, typically for 12 to 24, even 36 months. They bring the security leadership experience, build the program structure, and help you figure out what the permanent role should look like. In our experience, companies that use a fractional CISO during this transition end up hiring a better full-time CISO because they understand the role’s scope before they write the job description.

The Takeaway

Owning security as a CTO is a natural phase for growing software companies, not a failure. The goal is to be competent enough to protect the business and honest enough to recognize when competence isn’t sufficient anymore.

Measure a few things well. Delegate execution. And watch for the signals that you’ve outgrown the model. The companies that handle this transition smoothly are the ones that start planning the handoff before they’re underwater.

If you’re a CTO carrying the security function and wondering whether it’s time to bring in dedicated help, we’re happy to talk through what we’re seeing at similar companies. No pitch, just a conversation. Let’s talk.

About IOmergent
IOmergent provides fractional CISO services and managed cloud security for growing organizations that need experienced security leadership without a full-time hire. We help companies build security programs, manage cloud risk, and meet compliance requirements.