Closed-source software refers to programs whose source code isn’t shared with the public. You can use the app, but you can’t peek “under the hood” to see how it works or make changes.
If you’ve ever wondered what makes a program “closed source,” why it matters for cybersecurity, and how to spot risks and benefits, you’re in the right spot. We’ll break it all down with real-world examples, analogies, and some pro-level best practices—for everyone from cybersecurity newcomers to seasoned pros.
Closed-source software is software whose creators don’t release the program’s original instructions (called the “source code”) to the public. This means only authorized people (usually the software company’s employees and partners) can see, change, or share the code that makes the app run.
Anyone can buy, download, or use “closed source” software—but you won’t get access to what’s inside it or the ability to change how it works. Big names like Microsoft Office, Adobe Photoshop, and macOS fall into this category.
Simply put, it’s open. It comes down to transparency and control.
Closed source: Source code is hidden. Only the company or its partners can view or modify it. You can install and use the app, but that’s it.
Open source: Source code is shared publicly. Anyone can look at it, change it, or even help improve and redistribute it (as long as they follow some licensing rules).
Analogy time: Think of closed source like buying a car with the hood welded shut. You can drive it, but can’t tinker with the engine. Open source? That’s a car with a wide-open hood and a manual, free for you (and your friends) to fix, modify, or upgrade.
Closed-source software is everywhere. Some hallmarks:
Proprietary licensing: You pay for a license to use the software, not “own” it fully.
Updates and support: The company controls updates, bug fixes, and new features.
Limited customization: Customizing or expanding the program is usually a no-go (unless you have a special contract).
Legal restrictions: Reverse engineering or copying the software is restricted or outright illegal.
Everyday examples include:
Microsoft Office suite (Word, Excel, PowerPoint)
macOS and Windows operating systems
Adobe Creative Cloud (Photoshop, Illustrator)
Zoom, Slack, and most major antivirus programs
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:
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.
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.
Keep your devices and organization safe using these practical steps:
Update promptly: Always install patches and updates as soon as they’re available.
Understand vendor policies: Know how your vendor handles vulnerability disclosures, patch development, and support timelines.
Supplement with open source: Where possible, use open source alternatives for tasks that require more transparency.
Audit permissions: Limit software privileges to the minimum necessary for daily tasks.
Stay informed: Sign up for cybersecurity advisories that mention new vulnerabilities in the closed-source tools you use (US-CERT is a great start).
Closed-source software is a staple of the digital world, powering everything from personal laptops to massive enterprise networks. While you don’t get to peek at (or hack) the code, you do get structure, support, and a consistent experience.
Security isn’t about hiding your code; it’s about keeping your software well-maintained and informed. If you use closed-source tools, stay vigilant with updates, policy reviews, and basic cybersecurity hygiene. Mix in open-source options where transparency matters.
