What is closed-source software? Everything you need to know

There are a few big reasons organizations keep their code under wraps:

• Business interests: Protect intellectual property (IP), keep competitors from copying features or designs.

• Consistent user experience: Companies maintain full control over updates, ensuring things work as intended.

• Monetization: Closed-source software is often sold or licensed, making it easier to generate revenue.

• Security (with a caveat): By hiding the source code, it’s believed to be less vulnerable to attack, but that’s not always the case. (More on this below!)

How does closed-source software impact cybersecurity?

The cybersecurity stakes are high for all software, but closed-source comes with unique factors. Here’s the lowdown:

Pros of closed-source software for security

• Attack surface is hidden: If attackers can’t see the source code, it’s (slightly) harder to spot vulnerabilities.

• Controlled patching: The company has tight control over security updates, reducing “wild west” risk from haphazard third-party changes.

• Professional support: Most closed-source vendors offer dedicated security teams and customer support.

Cons of closed-source software for security

• Lack of transparency: Security researchers and defenders can’t easily audit how things work under the hood, so vulnerabilities might stay hidden for longer.

• Slow response to vulnerabilities: You're at the mercy of the vendor’s patching schedule.

• Risk of “security by obscurity”: Relying solely on hidden code for protection is weak; determined attackers can still reverse engineer apps.

Case in point: The infamous WannaCry ransomware used a vulnerability in closed-source Windows software. Because the code was hidden, many organizations didn’t know about the bug until after hackers did.