Whitelisting, blacklisting, and greylisting (sometimes graylisting) are integral to the security landscape of today's organizations, industries, and even governments. Despite that, the concept is fairly new to many businesses and individuals when it comes to understanding IT and cybersecurity.

Your security and functionality depend on how good you are at blacklisting, whitelisting, and graylisting. So what's the difference between the three? What are their pros and cons? And which is the best for you to implement?

What Is Whitelisting?

Whitelisting is a process in which you make a list of entities, apps, users, websites, behaviors, and/or regions, and grant them exclusive access or permissions in your system, devices, or assets.

Everyone and everything else is denied access by default. Only your whitelist is authorized to access and work with the assets in question.

There’s still a chance something might slip by if your system is big enough, your team is larger, or the members of the whitelist lenient enough to share access. Nonetheless, whitelisting is still one of the safest methods to block spam.

It may work well if you’re looking to protect an asset—like a database or classified records. But large businesses like eCommerce stores, big corporations, and other organizations can’t whitelist every process they carry out.

It impedes their growth by ruining the user experience, limiting their reach, and decreasing their options or opportunities.

Whitelisting is also not practical because the number of things you want to allow or need in your system often outnumber the entities you want to block. Sometimes, such cases are so severe that it takes years’ worth of trial and error to get the system to function.

Like every other mechanism, whitelisting has its pros and cons.

Pros

• Safe.
• Strict.
• Exclusive.
• Helps you maintain confidentiality.
• You’re aware of everyone and everything that has access.
• Easier to investigate and deal with breaches.

Cons

• Counterproductive for public-oriented organizations.
• Hard to maintain.
• Larger systems face greater malfunctions.

What Is Blacklisting?

Blacklisting is the exact opposite of whitelisting. It's when you create a list of entities, people, behavior, apps, algorithms, bots, and more to block them from your system and assets.

Everything else is allowed access by default. It works well for organizations looking to expand fast, attract the public, and run smoothly with little maintenance.

The blacklist needs constant updating because countless malware types and disguise tricks are discovered and exploited daily. If your system happens to have any zero-day vulnerabilities and your blacklist doesn’t have the malware targeting it listed, it's a matter of time before you suffer damage.

Pros

• Low maintenance.
• Keeps your system running smoothly.
• Doesn’t limit your opportunities.
• Takes fewer resources.
• Less manual labor.

Cons

• Risky.
• Newer Malware can slip by.
• Disguise techniques can work.

Disguise techniques can work on both the whitelists and the blacklists. The reason is that both of these lists look at filenames, sizes, and paths. If an attacker slips in a file with the same name and size and saves it in the same location, it can bypass whitelist-based security systems.

What Is Greylisting?

Most of our systems are multifaceted and complex. That’s why many of us use blacklisting and whitelisting simultaneously.

In such cases, we often come across a lot of things that are neither blacklisted nor whitelisted. That’s where greylisting comes in.

A greylist, or graylist, is a list of items, people, files, apps, algorithms, and more that you haven’t decided to blacklist or whitelist yet. These items go into the greylist until you decide which list to put them in or where they belong.

Greylists often come in handy for systems where you often need to allow temporary access to newcomers, visitors, or third parties.

What’s Better For You?

Blacklisting and whitelisting are both layers of security you can add to different areas of your system. If you must choose, you’ll have to figure out how your system works and so which would be more advantageous for each area.

If you have a huge number of operations and people you want to allow, to the point where you can’t name them all while you have a handful of things you need to block, blacklisting should be your go-to.

On the other hand, if you’re only comfortable with a few entities accessing your data or assets, you can create your whitelist and have their credentials on record.

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