Everything You Need to Know About Web Application Firewalls (WAFs)

This article is your one-stop, 360-degree useful resource protecting all the knowledge you want to learn about WAFs, together with how they perform, what they shield towards, how to implement them, and way more!

Protecting your internet functions towards malicious safety assaults is crucial. Luckily, WAFs (Web Application Firewalls) are right here to assist.

In a nutshell, a WAF works as a defend between the online software and the web, stopping mishaps that might happen with out it.

WAFs can shield you and your shoppers’ functions from cross-site forgery assaults, XSS (cross-site-scripting), and SQL injections, amongst others.

diagram of a wafWAFs are right here to assist shield your web site from hackers and malicious threats.

More and extra so, internet software safety has turn into extra essential, contemplating internet software assaults are one of the vital frequent causes for breaches.

As you’re about to see, WAFs are a vital a part of safety to guard towards vulnerabilities.

In this text, we’ll be protecting:

Let’s begin in the beginning, with…

What is a WAF?

A Web Application Firewall (WAF) is a particular sort of firewall that protects your internet functions from malicious application-based assaults.

In layman’s phrases, a WAF acts as the center particular person or safety guard on your WordPress web site.

It will assist shield internet functions from assaults like cross-site scripting (XSS), cookie poisoning, SQL injection, cross-site forgery, and extra.

WAFs will stand guard between the web and your internet functions, all of the whereas monitoring and filtering the HTTP visitors that wishes to get to your server.

It does this by adhering to insurance policies that help in figuring out what visitors is malicious and what visitors isn’t. Similar to how a proxy server acts as a mediator to shield the identification of a shopper, WAF capabilities in the same manner — however in reverse.

It’s a reverse proxy, which acts as a go-between that protects the online software server from a attainable malicious shopper.

WAFs use a algorithm (or insurance policies) to assist establish who’s truly in your visitor checklist and who’s simply trying to trigger hassle.

WAFs and Network Firewalls

WAFs shouldn’t be confused along with your customary Network Firewall (Packet Filtering), which assesses incoming information primarily based on a set of standards, together with IP addresses, packet sort, port numbers, and extra.

Network firewalls are okay and nice at what they do. The solely draw back is that they don’t perceive HTTP, and consequently, can’t detect particular assaults that focus on safety flaws in internet functions.

That’s the place WAFs save the day and may help bolster your internet safety in methods a Network Firewall can’t. There are many layers to it.

And using completely different safety measures may help you additional shield the person layers.

The OSI Model

To perceive these layers, you want to perceive the OSI Model (Open Systems Interconnection Model).

The OSI mannequin is a framework that divides the general structure of a community into seven completely different sections.

Every layer has its personal safety postures and mechanisms, and anybody overly involved with safety ought to understand how to detect and set up acceptable safety strategies for every.

The seven community layers are as follows:

A look at the various layers of a networkThe OSI mannequin breaks a community into seven distinct layers.

When analyzing the layers above, your typical Network Firewall helps safe layers 3 – 4, and a WAF assists with the safety of layer 7.

This also needs to function a reminder that WAFs are NOT a one-size-fits-all answer. And they’re greatest paired with different efficient safety measures – corresponding to a high quality Network Firewall.

Differences Between Network-Based, Host-Based, and Cloud-Based WAFs

WAFs are utilized in certainly one of three numerous methods — network-based, host-based, and cloud-based. Each has advantages and drawbacks, so let’s check out every one individually and see how they evaluate.

Network-Based: Network-based WAFs are usually hardware-based. They are put in domestically; subsequently they decrease latency. However, they’re an costly choice that additionally requires storage and upkeep of apparatus.

Host-Based: In phrases of prices, that is lower than network-based WAFs. Plus, it gives extra customization choices. One of the downsides of one of these WAF is the consumption of native server assets, upkeep prices, and it may be advanced to implement.

Cloud-Based: This is an reasonably priced choice — and it’s simple to implement. Usually, it’s only a matter of change in DNS to redirect visitors. Also, cloud-based WAFs have a low upfront price, with versatile cost choices. These WAFs are constantly up to date to assist shield towards the most recent threats that come up that received’t require any work or bills on the consumer’s aspect.

Probably the most important draw back of one of these WAF is it’s from a third get together supply, so you’re restricted to customization choices and rely solely on their providers.

Now that we now have a fundamental concept of what a WAF is and the differing types, let’s dive deeper into HOW it protects your treasured internet apps.

How WAFs Protect Your Web Applications From Malicious Attacks

According to a 2019 web applications report by Positive technologies, on common, hackers can assault customers in 9 out of 10 internet functions. Yikes!

The report additionally discovered that breaches of delicate information had been a risk in 68% of internet functions.

Statistics like these reinforce the necessity for simpler internet app safety.

As talked about earlier, WAFs shield your server by analyzing the HTTP visitors passing by means of – detecting and blocking something malicious BEFORE it reaches your internet functions (see beneath).

A look at how a WAF protects your site from cyber attacksTalk to the WAF hand pesky attacker.

As we simply mentioned, WAFs can be community ({hardware}) primarily based, software-based, or cloud-based, which means digital or bodily.

When it comes to how WAFs filter, detect, and block malicious visitors – they obtain this in a few alternative ways…

WAF Security Models: Blocklist, Allowlist, Or Both

WAFs usually observe both a “Blocklist” (unfavorable) or “Allowlist” (constructive) safety mannequin, or generally each.

When using a Blocklist safety mannequin, mainly, you’ll be able to assemble a listing of undesirable IP addresses or consumer brokers that your WAF will routinely block.

The Allowlist mannequin does the other and permits you to create an unique checklist of IP addresses and consumer brokers which might be permitted. Everything else is denied.

Both fashions have their execs and cons, so trendy WAFs usually supply a hybrid safety mannequin that offers you entry to each.

Attacks Prevented by WAFs

Obviously, not each assault on the market may be stopped by a WAF, nonetheless, they assist deal with a variety of them.

Some of the main assaults that WAF safety may help cease are:

SQL Injection: This is malicious code that’s injected or inserted into an online entry area. The injections permit assaults to compromise the appliance and likewise underlying techniques.

Cross-site Scripting (XSS): Client-side scripts are injected by attackers into internet pages different customers view.

Web Scraping: Used to extract information from web sites by information scraping.

Unvalidated Input: HTTP requests are tampered with by attackers to bypass safety mechanisms on a web site.

Cookie Poisoning: When a cookie is modified to acquire unauthorized information in regards to the consumer for malicious functions, corresponding to identification theft.

Layer 7 DoS: HTTP flood assault that makes use of legitimate requests in typical URL information.

Security enhancements are continuously being up to date and applied, so remember an excellent WAF can cowl much more than simply famous above.

When figuring out a WAF supplier, or implementing one, make certain it’s up-to-date and contains the necessities, particularly the OWASP Top 10 — which we’ll be discussing subsequent.

How WAFs Guard Your Web Apps Against The “The OWASP Top 10”

OWASP imageOWASP has a Top 10 that each one good WAFs ought to shield towards — or else that may sting.

As effectively as performing primarily based on one of many three safety fashions talked about earlier, WAFs come routinely armed with a particular algorithm (or insurance policies).

These insurance policies mix rule-based logic, parsing, and signatures to assist detect and stop many various internet software assaults like beforehand talked about.

In specific, WAFs are well-known for shielding towards a lot of the top 10 web application security risks listed yearly by OWASP (Open Web Application Security Project).

This contains malicious assaults corresponding to Server-Side Request Forgery (SSRF), Injections, and Security Logging.

Here’s a have a look at the present Top 10. You can see that there’s some consolidation and new classes from 2017.

owasp top 10These are what’s rating in 2021 for OWASP. (Source:

Find extra details about OWASP here.

Virtual Patch

Another satisfactory safeguard you’ll hear many WAF suppliers discuss is one thing known as a “virtual patch.”

A VP is basically a rule (or usually a algorithm) that may assist resolve a vulnerability in your software while not having to modify the code itself.

Many WAFs can deploy digital patches to restore WordPress core, plugin, and theme vulnerabilities when required.

How WAFs Also Help You Meet Legal Security Standards

Along with safety, a WAF may help with legalities.

If your group works with, processes, or shops delicate data (bank card particulars, and so on.), it’s important you adjust to safety necessities and requirements. This is the place a WAF comes into play.

WAFs may help companies of all sizes adjust to regulatory requirements just like the PCI, HIPAA, and GDPR, making the firewall precious from compliance and safety views.

For instance, the primary requirement for organizations beneath the Payment Card Industry Data Security Standard (PCI) is: “Installing and maintaining a firewall configuration to protect cardholder data.”

And let’s face it, maintaining in compliance with legalities additionally offers you an excellent popularity. It’s a win-win to use a WAF to meet authorized requirements.

Different Types of WordPress Firewalls

Considering WordPress is the world’s hottest content material supervisor and a frequent goal of assaults, it’s necessary WordPress websites have a WAF in place. There are a number of forms of firewalls varieties you’ll be able to deploy, that are:

  • WAF Security Plugins
  • On-site Dedicated WordPress WAFs
  • Online WordPress Website WAFs

Here’s a have a look at every one.

WAF Security Plugins

Most self-hosted WordPress firewalls are WordPress plugins. They’re perfect, contemplating how simple they’re to implement and reasonably priced. Plus, it’s frequent for the WAF plugins to have malware scanners, too.

Some observe a “SAAS” mannequin, providing a simple and stress-free introduction to the world of software firewalls.

On the opposite aspect of the coin, some plugins received’t match the invoice.  It’s all depending on the extent at which the WAF sits.

For instance, some plugin WAFs sit on the DNS stage, which normally means the firewall displays and filters HTTP visitors earlier than reaching their cloud proxy servers.

This is the advisable stage for these sorts of firewall plugins. Some well-known WAF suppliers are arrange on this manner (e.g. Cloudflare — which is likely one of the suppliers we’ll be discussing later on this article).

Then you’ve different WordPress safety plugins with built-in WAFs that sit on the software stage. This means the firewall examines incoming visitors after it has already reached your server – however earlier than loading WordPress scripts.

Plugins are a easy and efficient answer to WAF and usually work for small or medium-sized web sites. We’ll be going over some choices of WAF distributors in a while on this article.

On-site Dedicated WordPress WAFs

These forms of firewalls are put in between your WordPress websites and an web connection. This implies that each HTTP request despatched to your WordPress web site initially passes by means of the WAF.

Web software WAFs are a bit safer opinion than plugins. That being stated, they’re dearer and would require some technical data to handle.

Online WordPress Firewalls

This sort of firewall doesn’t want to be put in on the identical community as your webserver to perform. It’s a web-based service that works like a proxy server, the place your web site’s visitors comes by means of it for filtering and is then forwarded to your web site.

With a web-based WordPress firewall, your web site’s area’s DNS information will want to be configured to level to the web WAF. So, this entails your WordPress guests speaking with the web WordPress firewall, not exactly along with your WordPress web site.

The draw back? Your internet server wants to be accessible over the web for the WAF to ahead visitors to your web site. In different phrases, individuals can proceed to talk straight along with your internet server if the IP tackle is thought.

Basically, in a non-targeted WordPress assault, during which attackers scan whole networks for weak websites, your internet server and web site will nonetheless be reachable.

Luckily, you’ll be able to configure your server’s firewall to solely reply to visitors coming from the web WordPress firewall, so if this assault occurs, you received’t be a sufferer.

Limitations of WordPress Firewalls

Like something, firewalls may be imperfect. Sure, they provide added safety, however there are some vulnerabilities.

A few examples of this are Limited Zero-Day Vulnerability Protection, and Web Application Firewall Bypasses.

With the zero-day WordPress vulnerability, there’s potential that your WordPress firewall received’t block an assault.

This is why your vendor responsive menu is vital. Plus, it’s best to all the time use software program from responsive and trusted companies to make sure the firewall guidelines are up to date.

In the case of internet software firewall bypasses, it’s only a matter of them having vulnerabilities. There are strategies on the market about bypassing the safety of WAFs.

Here once more, in case your vendor is responsive and might remediate points in a fast timeframe, try to be okay.

It’s additionally not unusual for WAFs to have false positives (the place they block innocent visitors) and false negatives (letting dangerous visitors by means of). This is as a result of the appliance is protected by WAF adjustments usually.

Additionally, some safety protocols are sometimes uncared for. This contains preventative measures, corresponding to code and infrastructure audits not being taken.

There will all the time be new WAF vulnerabilities that come up as new digital instruments emerge. Many safety points get resolved, however some aren’t observed immediately.

All this being stated, WAFs want to be actively maintained and configured to guarantee they’re up-to-date.

WAF Deployment

WAFs are deployed in a number of methods. This all is determined by the place your functions are deployed, what providers are wanted, the way you need them managed, and the extent of flexibility and efficiency required.

Here’s the fast rundown…

Reverse Proxy: The WAF is a proxy to the appliance server, so gadget visitors heads straight to the WAF.

Transparent Reverse Proxy: This is a reverse proxy with clear mode. Because of this, the WAF individually sends filtered visitors to internet functions, which permits for IP masking by having the tackle of the appliance server hidden.

Transparent Bridge: This is the place HTTP visitors goes straight to the online software. The result’s the WAF is clear between the gadget and the server.

You’ll have to determine what technique of deployment works greatest and covers all that you simply want.

WAF Vendors

When it comes to implementing WAFs, there’s no scarcity of firms and distributors which might be on the market to assist. Just google “WAF Vendors” — and a ton of outcomes will seem, together with a variety of Top 10 lists and extra.

That being stated, here’s a have a look at a few of the high firms on the market which have caught out to us as main contenders when it comes to WAFs. They all have options that cater to particular person wants.

We’ll check out the next WAF distributors:

  • AWS
  • Cloudflare
  • Azure
  • Imperva
  • Prophaze
  • Akamai
  • Wordfence
  • Sucuri

There’s a abstract of who they’re and what they’re greatest at. Plus, we’ll level out a few of the high options of every firm and the numerous preventative safety measures they maintain.


aws logo.AWS is a superb WAF answer for small to giant companies.

Amazon’s AWS WAF helps cease assaults from internet exploits and bots that may alter availability, have an effect on your safety, and eat a ton of assets.

With this WAF, you’ll be in command of how visitors reaches your functions by organising safety guidelines that run bot visitors and block frequent assault patterns (e.g. SQL Injections).

This WAF is deployed on Amazon CloudEntrance as a part of your CDN. What’s particularly beautiful about this WAF is that you simply pay just for what you employ, and the prices are primarily based on the variety of guidelines you’ve. Plus, there are prices related to the variety of internet requests your software receives.

Top Features: Amazon’s AWS WAF contains its cost-effective internet software safety. Along with that, it has an ease of deployment and upkeep. Security can also be built-in relying on the way you develop your functions, providing you with extra customization choices than different WAFs.

Best For: Businesses of all sizes, so long as they’re AWS shoppers.

Helps Mitigate: DDoS assaults, SQL Injections, and Cross-Site Scripting (XSS).


Cloudflare logo.Cloudflare is right here to assist safe your belongings with layered defenses.

Cloudflare is a top-rated cloud-delivered software safety firm. And, after all, a strong WAF is built-in with its safety. Their WAF blocks over 57 billion cyber threats per day.

Its world 100 Tbps community sees 30M requests per second, so it’s up for the job when it comes to dealing with your web sites. It gives full software safety from the identical cloud community, making it sensible and uniform when it comes to safety posture.

Cloudflare’s community has unparalleled visibility into threats, which yields the sharpest and handiest machine studying.

Top Features: It has layered defenses, together with Cloudfare managed guidelines, that supply superior zero-day vulnerability protections. Plus, it makes use of the core OWASP guidelines, makes use of customized rulesets, displays & blocks stolen or uncovered credentials, and has versatile response choices.

Additionally, it has logging & reporting, problem monitoring, analytics, and application-layer management.

Best For: Personal use to small and mid-sized companies. Also, it’s wonderful for high-level enterprises and corporations. Plus, it has WordPress WAF guidelines, so it’s nice for WordPress websites.

Helps Mitigate: OWASP Top 10, Comment Spam, DDoS assaults, SQL injections, HTTP Headers, and extra.


Azure logo.Azure is Microsoft’s WAF answer.

Microsoft’s Azure is a cloud-native WAF that is likely one of the most profitable cloud platforms on the market.

The Azure service gives a spread of software program that present utilities to different techniques, and one of many merchandise is the WAF. It tracks for the highest ten vulnerabilities logged by OWASP, and you may add customized guidelines, too.

It has a metered cost charge, calculated on an hourly charge and information throughput charge — then charged month-to-month. This gives a lot decrease upfront prices in contrast to another WAF suppliers.

Top Features: Azure has complete safety for OWASP, real-time visibility into your setting, and safety alerts. Plus, it has full REST API help in order that it could automate DevOps processes. It additionally has DDoS safety.

Best For: Major and small companies, alike.

Helps Mitigate: OWASP Top 10, DDos Attacks, and any customized guidelines (and extra).


wpmu dev logoYes, our internet hosting features a WAF.

We couldn’t let this text go by with out mentioning our very own highly optimized WAF here at WPMU DEV. Our WAF is completely free to use with our hosting, already tweaked for WordPress, updated daily, and much more.

The WAF we use uses fewer server resources by not running in PHP. Additionally, it doesn’t need to use a line of code, so your site’s performance will remain strong.

We also have over 300+ firewall rules (or policies). These policies combine rule-based logic, parsing, and signatures — which lets them detect and stop web application attacks.

See how to implement our WAF in this article.

Top Features: After testing, our WAF is 25% faster than leading plugin-based firewall. On top of our 300+ firewall ruleset, we also protect against the OWASP Top Ten. Additionally, it’s free with any hosted account!

Best For: Small to major WordPress sites, hosting resellers, and any agency or individual that manages multiple websites.

Helps Mitigate: Attacks ranging from SQL injections, XSS, and many more.


Imperva logo.Imperva is a great option that you can try for free.

Imperva’s WAF stops assaults with virtually zero errors when it comes to false positives. It additionally has a worldwide SOC to be sure that your organization is protected inside moments of discovery.

It’s an all-in-one safety answer that has all of the options required for web site safety. There are free instruments for Data Classification and Database Vulnerability Testing.

Top Features: Imperva options safe cloud and on-premises functions. It stops OWASP Top 10 and Automated Top 20, plus has assault detection, SIEM integration, and reporting.

Best For: Small to large-sized firms.

Helps Mitigate: OWASP Top 10 and Automated Top 20 and extra.


Prophaze logoPorphaze gives limitless rule units.

Prophaze WAF handles a ton when it comes to safety. Not solely is it a WAF, nevertheless it’s additionally a mixture of RASP, CDN, DDoS, and extra.

It gives real-time web site safety by implementing highly effective cloud-based applied sciences that work towards the newest threats. It routinely scans your web site for 1000’s of vulnerabilities and the OWASP Top 10. On high of that, it doesn’t want any extra configurations and computerized updates to deal with new threats.

Prophaze has limitless rule units. Plus, customized integrations with SIEM Solutions and helps all public clouds (e.g. AWS).

Top Features: Some key safety features are Bot Migration, Real-Time Dashboard, 24-7 help, and ML Based Threat Intelligence.

Best For: A spread from midmarket to excessive stage enterprise.

Helps Mitigate: OWASP Top 10 API, DDoS, Bot Protection, and extra.


Akamai WAF image.Akamai WAF makes use of crowdsourced intelligence to assist shield towards threats.

Akamai’s WAF is a reliable answer that can shield your web site towards all identified assaults. Its a world chief in DDoS, plus integrates full DDoS safety with its WAF. That makes it so that you received’t want to have visitors routed by means of two firms to obtain constructive requests to your internet server.

With Akamai, detect threats with crowdsourced intelligence. Plus, deploy and handle effectively with just some clicks.

Top Features: Akamai has extra automation than many different choices. It’s additionally simple to use with safety towards DDoS assaults and extra. It additionally includes a dashboard, alerts, and extra details about blocked assaults and the way your web site was protected.

Best For: Small to Large Companies

Helps Mitigate: DDoS Attacks and all OWASP Top 10.


Wordfence logoWordfence is a WAF that runs on the endpoint, which makes for deep integration with WordPress.

Wordfence is one other strong choice for a WAF that’s made for WordPress websites as a well-liked all-in-one safety plugin with over two million lively installs. It contains an endpoint firewall and malware scanner that was particularly constructed for WordPress.

Its WAF runs on the endpoint, which permits deep integration with WordPress, which is completely different than cloud options because it doesn’t break encryption, can’t be bypassed, and might’t leak information.

It additionally comes with a pleasant dashboard that signifies safety threats, scans, and extra.

Top Features: Spam filter, scheduled safety scans, brute pressure assault prevention, stay visitors monitoring, and extra.

Best For: WordPress websites and small to giant firms.

Helps Mitigate: Brute pressure assaults, OWASP Top 10, and different malicious assaults.


sucuri logoAnother wonderful choice on your WAF and WordPress.

Sucuri is a number one safety firm for WordPress. It includes a cloud-based WAF that’s constantly up to date to enhance detection and mitigation towards new and evolving threats. Plus, you’ll be able to add your personal customized guidelines.

With Sucuri, you may also improve your WordPress’s efficiency. It options caching optimization, Analyst CDN, and web site acceleration.

Top Features: DNS Level Firewall, malware & blocklist removing providers, and brute pressure safety.

Best For: WordPress websites and corporations/companies of any measurement.

Helps Mitigate: All identified assaults (e.g. SQL injections, RCE, RFU, and so on.).

Of course, there are a lot of extra choices on the market as effectively. This is only a shortlist of some extremely rated firms that may serve you effectively when it comes to WAFs.

It’s No Gaffe That You Need a WAF

Now that we’ve coated the spectrum of WAFs, in case you didn’t know, you’ll be able to see that they’re useful for safety, compliance, popularity, and peace of thoughts. And hopefully, you realized extra about WAFs than you ever thought you’d!

Plus, with the various distributors to present a WAF, you’ll be able to have one up and working in a matter of moments. Whether you run a WordPress web site or not — there’s a WAF for you.

Hopefully, this reference information has helped to reply any questions you or your shoppers have about WAFs.

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