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

This text is your one-stop, 360-degree useful resource masking all the knowledge you want to learn about WAFs, together with how they perform, what they defend in opposition to, how to implement them, and far more!

Defending your net purposes in opposition to malicious safety assaults is crucial. Fortunately, WAFs (Web Application Firewalls) are right here to assist.

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

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

WAFs are right here to assist defend your website from hackers and malicious threats.

An increasing number of so, net utility safety has change into extra essential, contemplating net utility assaults are one of the vital widespread causes for breaches.


As you’re about to see, WAFs are a important a part of safety to guard in opposition to vulnerabilities.

On this article, we’ll be masking:

Let’s begin firstly, with…

What’s a WAF?

A Web Application Firewall (WAF) is a selected kind of firewall that protects your net purposes from malicious application-based assaults.

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


It should assist defend net purposes 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 net purposes, all of the whereas monitoring and filtering the HTTP site visitors that desires to get to your server.

It does this by adhering to insurance policies that help in figuring out what site visitors is malicious and what site visitors isn’t. Comparable to how a proxy server acts as a mediator to defend the id of a consumer, WAF features in an analogous means — however in reverse.

It’s a reverse proxy, which acts as a go-between that protects the net utility server from a potential malicious consumer.

WAFs use a algorithm (or insurance policies) to assist determine who’s truly in your visitor listing and who’s simply wanting to trigger bother.

WAFs and Community Firewalls

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

Community firewalls are okay and nice at what they do. The one draw back is that they don’t perceive HTTP, and in consequence, can’t detect particular assaults that focus on safety flaws in net purposes.

That’s the place WAFs save the day and may also help bolster your net safety in methods a Community Firewall can’t. There are various layers to it.

And using totally different safety measures may also help you additional defend the person layers.

The OSI Mannequin

To grasp 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 totally different sections.

Each layer has its personal safety postures and mechanisms, and anybody overly involved with safety ought to know the way to detect and set up applicable 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 Community 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 resolution. They usually’re finest paired with different efficient safety measures – reminiscent of a high quality Community Firewall.

Variations Between Community-Based mostly, Host-Based mostly, and Cloud-Based mostly WAFs

WAFs are utilized in one in all three varied methods — network-based, host-based, and cloud-based. Every has advantages and drawbacks, so let’s check out each individually and see how they evaluate.

Community-Based mostly: Community-based WAFs are sometimes hardware-based. They’re put in regionally; due to this fact they reduce latency. Nevertheless, they’re an costly choice that additionally requires storage and upkeep of apparatus.

Host-Based mostly: By way of prices, that is lower than network-based WAFs. Plus, it provides extra customization choices. One of many downsides of this kind of WAF is the consumption of native server assets, upkeep prices, and it may be advanced to implement.

Cloud-Based mostly: That is an reasonably priced choice — and it’s simple to implement. Normally, it’s only a matter of change in DNS to redirect site visitors. Additionally, cloud-based WAFs have a low upfront price, with versatile cost choices. These WAFs are persistently up to date to assist defend in opposition to the most recent threats that come up that gained’t require any work or bills on the consumer’s facet.

In all probability the most important draw back of this kind of WAF is it’s from a third occasion supply, so you’re restricted to customization choices and rely solely on their companies.

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

How WAFs Defend Your Web Purposes From Malicious Assaults

In accordance to a 2019 web applications report by Positive technologies, on common, hackers can assault customers in 9 out of 10 net purposes. Yikes!

The report additionally discovered that breaches of delicate information had been a menace in 68% of net purposes.

Statistics like these reinforce the necessity for more practical net app safety.

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

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

As we simply mentioned, WAFs will also 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 site visitors – they obtain this in a few alternative ways…

WAF Safety Fashions: Blocklist, Allowlist, Or Each

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

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

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

Each fashions have their execs and cons, so fashionable WAFs usually provide a hybrid safety mannequin that offers you entry to each.

Assaults Prevented by WAFs

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

A few of the main assaults that WAF safety may also help cease are:

SQL Injection: That is malicious code that’s injected or inserted into an online entry subject. The injections permit assaults to compromise the applying and likewise underlying programs.

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

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

Unvalidated Enter: HTTP requests are tampered with by attackers to bypass safety mechanisms on a website.

Cookie Poisoning: When a cookie is modified to achieve unauthorized information concerning the consumer for malicious functions, reminiscent of id theft.

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

Safety enhancements are continually being up to date and applied, so have in mind 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 consists of the necessities, particularly the OWASP High 10 — which we’ll be discussing subsequent.

How WAFs Guard Your Web Apps Towards The “The OWASP High 10”

OWASP imageOWASP has a High 10 that every one good WAFs ought to defend in opposition to — or else that may sting.

In addition to performing primarily based on one of many three safety fashions talked about earlier, WAFs come mechanically armed with a selected algorithm (or insurance policies).

These insurance policies mix rule-based logic, parsing, and signatures to assist detect and forestall many alternative net utility assaults like beforehand talked about.

Specifically, WAFs are well-known for safeguarding in opposition to a variety of the top 10 web application security risks listed yearly by OWASP (Open Web Application Safety Venture).

This consists of malicious assaults reminiscent of Server-Aspect Request Forgery (SSRF), Injections, and Safety Logging.

Right here’s a take a look at the present High 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. (Supply:

Discover extra details about OWASP here.

Digital Patch

One other ample safeguard you’ll hear many WAF suppliers speak about is one thing referred to as a “digital patch.”

A VP is basically a rule (or usually a algorithm) that may assist resolve a vulnerability in your software without having to alter the code itself.

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

How WAFs Additionally Assist You Meet Authorized Safety Requirements

Together with safety, a WAF may also help with legalities.

In case your group works with, processes, or shops delicate data (bank card particulars, and many others.), it’s important you adjust to safety necessities and requirements. That is the place a WAF comes into play.

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

For instance, the primary requirement for organizations below the Payment Card Industry Data Security Standard (PCI) is: “Putting in and sustaining a firewall configuration to defend cardholder information.”

And let’s face it, conserving in compliance with legalities additionally provides you a terrific status. It’s a win-win to use a WAF to meet authorized requirements.

Completely different Forms of WordPress Firewalls

Contemplating 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 sorts of firewalls varieties you’ll be able to deploy, that are:

  • WAF Safety Plugins
  • On-site Devoted WordPress WAFs
  • On-line WordPress Web site WAFs

Right here’s a take a look at each.

WAF Safety Plugins

Most self-hosted WordPress firewalls are WordPress plugins. They’re preferrred, contemplating how simple they’re to implement and reasonably priced. Plus, it’s widespread 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 utility firewalls.

On the opposite facet of the coin, some plugins gained’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 degree, which often means the firewall screens and filters HTTP site visitors earlier than reaching their cloud proxy servers.

That is the beneficial degree for these sorts of firewall plugins. Some well-known WAF suppliers are arrange on this means (e.g. Cloudflare — which is without doubt one of the suppliers we’ll be discussing later on this article).

Then you could have different WordPress safety plugins with built-in WAFs that sit on the utility degree. This implies the firewall examines incoming site visitors after it has already reached your server – however earlier than loading WordPress scripts.

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

On-site Devoted WordPress WAFs

A majority of these firewalls are put in between your WordPress websites and an web connection. Which means each HTTP request despatched to your WordPress website initially passes by means of the WAF.

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

On-line WordPress Firewalls

One of these 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 website’s site visitors comes by means of it for filtering and is then forwarded to your web site.

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

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

Principally, in a non-targeted WordPress assault, during which attackers scan whole networks for weak websites, your net server and website will nonetheless be reachable.

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

Limitations of WordPress Firewalls

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

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

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

This is the reason your vendor responsive menu is important. Plus, you must at all times use software program from responsive and trusted companies to make sure the firewall guidelines are up to date.

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

Right here once more, in case your vendor is responsive and may remediate points in a fast timeframe, you have to be okay.

It’s additionally not unusual for WAFs to have false positives (the place they block innocent site visitors) and false negatives (letting dangerous site visitors by means of). It is because the applying is protected by WAF adjustments recurrently.

Moreover, some safety protocols are sometimes uncared for. This consists of preventative measures, reminiscent of code and infrastructure audits not being taken.

There’ll at all times be new WAF vulnerabilities that come up as new digital instruments emerge. Many safety points get resolved, however some aren’t seen immediately.

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

WAF Deployment

WAFs are deployed in just a few methods. This all depends upon the place your purposes are deployed, what companies are wanted, the way you need them managed, and the extent of flexibility and efficiency required.

Right here’s the fast rundown…

Reverse Proxy: The WAF is a proxy to the applying server, so machine site visitors heads straight to the WAF.

Clear Reverse Proxy: It is a reverse proxy with clear mode. Due to this, the WAF individually sends filtered site visitors to net purposes, which permits for IP masking by having the tackle of the applying server hidden.

Clear Bridge: That is the place HTTP site visitors goes straight to the net utility. The result’s the WAF is clear between the machine and the server.

You’ll have to resolve what technique of deployment works finest and covers all that you just want.

WAF Distributors

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

That being mentioned, here’s a take a look at a number of the high firms on the market which have caught out to us as main contenders when it comes to WAFs. All of them 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 finest at. Plus, we’ll level out a number of the high options of every firm and the numerous preventative safety measures they handle.


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

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

With this WAF, you’ll be accountable for how site visitors reaches your purposes by establishing safety guidelines that run bot site visitors and block widespread assault patterns (e.g. SQL Injections).

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

High Options: Amazon’s AWS WAF consists of its cost-effective net utility safety. Together with that, it has an ease of deployment and upkeep. Safety can also be built-in relying on the way you develop your purposes, supplying you with extra customization choices than different WAFs.

Greatest For: Companies of all sizes, so long as they’re AWS shoppers.

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


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

Cloudflare is a top-rated cloud-delivered utility safety firm. And, in fact, 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 provides full utility 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 simplest machine studying.

High Options: 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, screens & blocks stolen or uncovered credentials, and has versatile response choices.

Moreover, it has logging & reporting, concern monitoring, analytics, and application-layer management.

Greatest For: Private use to small and mid-sized companies. Additionally, it’s wonderful for high-level enterprises and firms. Plus, it has WordPress WAF guidelines, so it’s nice for WordPress websites.

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


Azure logo.Azure is Microsoft’s WAF resolution.

Microsoft’s Azure is a cloud-native WAF that is without doubt one of the most profitable cloud platforms on the market.

The Azure service provides a spread of software program that present utilities to different programs, and one of many merchandise is the WAF. It tracks for the highest ten vulnerabilities logged by OWASP, and you’ll 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 supplies a lot decrease upfront prices in contrast to another WAF suppliers.

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

Greatest For: Main and small companies, alike.

Helps Mitigate: OWASP High 10, DDos Assaults, and any customized guidelines (and extra).


wpmu dev logoSure, 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 make sure that your organization is protected inside moments of discovery.

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

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

Greatest For: Small to large-sized firms.

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


Prophaze logoPorphaze provides limitless rule units.

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

It provides real-time web site safety by implementing highly effective cloud-based applied sciences that work in opposition to the newest threats. It mechanically scans your website for 1000’s of vulnerabilities and the OWASP High 10. On high of that, it doesn’t want any further configurations and automated updates to sort out new threats.

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

High Options: Some key safety features are Bot Migration, Actual-Time Dashboard, 24-7 assist, and ML Based mostly Risk Intelligence.

Greatest For: A spread from midmarket to excessive degree enterprise.

Helps Mitigate: OWASP High 10 API, DDoS, Bot Safety, and extra.


Akamai WAF image.Akamai WAF makes use of crowdsourced intelligence to assist defend in opposition to threats.

Akamai’s WAF is a reliable resolution that may defend your website in opposition to all identified assaults. Its a world chief in DDoS, plus integrates full DDoS safety with its WAF. That makes it so that you gained’t want to have site visitors routed by means of two firms to obtain constructive requests to your net server.

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

High Options: Akamai has extra automation than many different choices. It’s additionally simple to use with safety in opposition to DDoS assaults and extra. It additionally incorporates a dashboard, alerts, and extra details about blocked assaults and the way your website was protected.

Greatest For: Small to Massive Firms

Helps Mitigate: DDoS Assaults and all OWASP High 10.


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

Wordfence is one other stable 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 consists of 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 totally different than cloud alternate options because it doesn’t break encryption, can’t be bypassed, and may’t leak information.

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

High Options: Spam filter, scheduled safety scans, brute drive assault prevention, stay site visitors monitoring, and extra.

Greatest For: WordPress websites and small to giant companies.

Helps Mitigate: Brute drive assaults, OWASP High 10, and different malicious assaults.


sucuri logoOne other wonderful choice on your WAF and WordPress.

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

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

High Options: DNS Degree Firewall, malware & blocklist elimination companies, and brute drive safety.

Greatest For: WordPress websites and firms/companies of any dimension.

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

After all, there are lots of extra choices on the market as effectively. That 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 lined the spectrum of WAFs, in case you didn’t know, you’ll be able to see that they’re helpful for safety, compliance, status, and peace of thoughts. And hopefully, you discovered 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 operating in a matter of moments. Whether or not you run a WordPress website 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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