WAF Malware Prevention

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Web Application Firewall Malware –  Before we start discussing about WAF, let us explain some basics of Web Aplication Firewall (WAF)

What is a Web Application Firewall (WAF)?

A WAF, or Online Application Firewall, aids in protecting web applications by filtering and monitoring HTTP traffic between the web application and the Internet. It typically protects online applications from cross-site forgery, cross-site scripting (XSS), file inclusion, and SQL injection, among other things. A WAF is a protocol layer 7 (in the OSI model) defense that is not intended to fight against all forms of attacks. Instead, this form of attack mitigation is typically part of a suite of technologies that, when combined, create a comprehensive defense against a variety of attack vectors.

When a WAF is deployed in front of a web application, it creates a barrier between the web application and the Internet. While a proxy server protects the identity of a client machine by acting as an intermediary, a WAF is a form of reverse proxy that protects the server from exposure by requiring clients to pass through the WAF before accessing the server.

A WAF runs according to a set of rules known as policies. These policies try to guard against application vulnerabilities by screening out harmful traffic. The utility of a WAF stems in part from the speed and ease with which policy modifications may be deployed, allowing for speedier reaction to various attack vectors; for example, rate restriction can be swiftly imposed during a DDoS attack by modifying WAF policies.

What is the operation of a web application firewall (WAF)?

A WAF secures your online applications by filtering, monitoring, and blocking any harmful HTTP/S traffic that arrives at the web application, as well as preventing unauthorized data from exiting the app. It accomplishes this by following a set of policies that determine what traffic is malicious and what traffic is safe. Thus, in the same way, a proxy server functions as an intermediary to safeguard a client’s identity. A WAF operates in the opposite direction—as a reverse proxy—acting as an intermediary to protect the web app server from a potentially dangerous client.

WAFs can be offered as software, an appliance, or a service. Policies can be tailored to match the specific requirements of your online application or set of web applications. Although many WAFs require you to update the policies regularly to handle new vulnerabilities, developments in machine learning allow some WAFs to update automatically. This automation is becoming increasingly important as the threat landscape becomes more complicated and ambiguous.

What is the difference between allowlist and blocklist WAFs?

A WAF that uses a blocklist (negative security paradigm) defends against known threats. For example, consider a blocklist WAF to be a club bouncer who is told to refuse admission to guests who do not adhere to the dress code. A WAF based on an allow list (positive security model), on the other hand, only allows pre-approved traffic. This is analogous to the bouncer at a private party; they only admit those on the list. Of course, both blocklists and allowlists have advantages and disadvantages, which is why many WAFs provide a hybrid security strategy that incorporates both.

What is the difference between network-based, host-based, and cloud-based WAFs?

A WAF can be implemented in one of three methods, each with its own set of advantages and disadvantages:

In most cases, a network-based WAF is hardware-based. Because they are placed locally, they reduce latency; however, network-based WAFs are the most expensive solution and necessitate the storage and maintenance of physical equipment.

A host-based WAF can be entirely incorporated into the software of an application. This approach is less expensive and more customizable than a network-based WAF. The disadvantages of a host-based WAF are local server resources, the complexity of the deployment, and maintenance costs. These components usually necessitate engineering work and can be pricey.

Cloud-based WAFs are a low-cost, easy-to-implement solution; they often provide a turnkey installation that is as simple as a DNS update to reroute traffic. Cloud-based WAFs also offer a low upfront cost because users pay for security as a service monthly or annually. Cloud-based WAFs can also provide a constantly updated solution to protect against the most recent attacks with no additional labor or cost on the user’s part. The disadvantage of a cloud-based WAF is that users take over the responsibility to a third party. Therefore some functionalities of the WAF may be opaque to them.

WAF Malware Prevention

How do web application firewalls work?

Web application firewalls (WAFs) are designed to be installed on the application layer, acting as a two-way gatekeeper and analyzing HTTP/HTTPS traffic entering and exiting the application; the WAF will take action anytime harmful activity is detected. WAFs have the advantage of operating independently of the application while constantly adapting to changes in application behavior. As a result, adding a new feature to the application will not result in hundreds of false-positive threat detections triggered by new data flows.

A WAF can be installed on a dedicated physical server, and while it is commonly regarded as a stand-alone application, it can also be connected with other networking components. In addition, WAF can be configured to provide several levels of scrutiny, typically on a scale of low to high, allowing the WAF to provide a higher level of protection and mitigation for the web application based on your needs. WAFs are also subject to regulatory regulations, such as the Payment Card Industry Data Security Standard (PCI DSS) and the Health Insurance Portability and Accountability Act of 1996. (HIPAA).

Request analysis and application of filter rules

WAFs evaluate all traffic or requests that reach the web application, determine whether the traffic is “healthy,” and then either approve or refuse the harmful traffic flow. Rules and policies are recommendations designed to assist the WAF in making an informed decision; these rules and policies operate at a higher level than standard firewall rules and exceptions.

WAFs employ multiple layers of filters when monitoring traffic, frequently looking for zero-day attacks, client-side attacks, bot attacks (such as DDoS attacks), hidden virus files, and web application vulnerabilities. The most sophisticated WAFs can decode and analyze HTTPS traffic and XML, JSON, and other popular data transmission types. It aids in the detection of attacks designed to circumvent the firewall, such as HPC, HPP, and Verb Tampering.

7 Types of Cyberattacks WAF Can Stop

DDoS Attacks

DDoS attacks attempt to flood a target online application/website/server with bogus traffic, depleting network bandwidth and rendering it unavailable to real users. DDoS assaults can occur in a variety of methods, including amplification, flooding, protocol-based, and reflection. DNS amplification, Ping of death, Smurf attacks, HTTP flood, SYN flood, and more frequent yet deadly types of DDoS attacks are listed here.

WAFs prevent these attacks by scanning applications on a daily basis, monitoring them around the clock, using Global Threat Intelligence, and using Machine Learning to recognise and block imposter bots, malicious requests, and so on.

SQL Injection Attacks

In these attacks, the perpetrator injects malicious SQL code into user input fields on web applications such as submission forms, contact forms, and so on. By doing so, they get access to the application’s backend database, where they can steal sensitive and secret information from customers or the business itself, gain unauthorised administrative access, edit or delete data, and so on, or even gain complete control of the online application. SQL Injection attacks are mostly caused by user input fields and submission forms that are not protected against the insertion of code and other un-sanitized inputs.

Cross-Site Scripting (XSS) Attacks

XSS attacks target users of vulnerable web applications/websites to obtain access to and control over their browsers. In this case, the attackers exploit application vulnerabilities and gaps to inject malicious scripts/codes that are executed when an unsuspecting user loads the application/website. In reflected XSS attacks, the malicious code is executed only if the user clicks the link, whereas in stored XSS attacks, the malicious payload is stored in the web browser and executed every time the user visits the website/application (it makes no difference whether they viewed/ downloaded/ clicked the link). XSS attacks damage the user’s personal and confidential information and frequently result in identity theft, session hijacking, and other malicious activities. These attacks occur either because user input areas like as comment sections, user posts, feedback, and so on are not sanitised and hence allow unencoded/ invalid inputs, or because the programme contains legacy/ redundant VBScript, Active X, JavaScript, and so on.

Zero-day Attacks

Zero-day attacks occur when an organization is unaware of the existence of vulnerabilities in hardware or software until the attack occurs. These are unforeseen and, as a result, extremely destructive to organizations because they lack quick remedies or patches to protect their application. Cyber-attackers, on the other hand, could have been snooping around the application for a long time and exploited the weaknesses as soon as they were discovered.

Business Logic Attacks

Business logic is the important component that connects and passes information between the UI and databases and software systems, allowing users to use the web application/website successfully. When there are gaps, mistakes, or overlaps in the business logic, vulnerabilities are created that are frequently exploited by cyber-attackers for monetary and other benefits. Malformed requests and malicious payload are not used by attackers to coordinate business logic attacks. They exploit contextual flaws in the application by using valid values and legal requests. These assaults are frequently carried out using Business Logic Bots.

Managed WAFs are ideally suited to combating these threats because they combine machine scalability, speed, and accuracy with the skill, intellect, and creative-thinking talents of qualified security specialists who understand the business.

Man-in-the-middle attacks

These occur when attackers place themselves between the application and genuine users in order to obtain personal information such as passwords, login credentials, credit card information, and so on by impersonating one of the two parties. The assault can be carried out using easy methods such as providing free, malicious hotspots in public places that are not password protected. When victims connect to these hotspots, the attacker gains complete view of their online data exchange. For interception of the connection, sophisticated measures such as DNS cache poisoning, IP spoofing, ARP spoofing, and so on are employed, while HTTPS spoofing, SSL hijacking, SSL beast, and so on are used for decryption of the two-way SSL communication without alerting the user or the application.


In defacement assaults, the culprits change the website content and replace it with their own content to reflect a political ideology/ agenda, shock people with provocative messages or imagery, and so on. Users may be unable to use the online application until the defacement is repaired.

As previously said, Web Application Firewalls that are controlled, intelligent, and equipped with Global Threat Intelligence and Machine Learning capabilities can successfully and efficiently combat each of these eight forms of cyber-attacks.

Web application firewalls are classified into several types.

Web application firewall that is network-based

Network-based web application firewalls (NWAF) are generally hardware-based and benefit from latency reduction due to local installation. This means that NWAF is installed near the application server and is easily accessible. Furthermore, NWAFs support rule and setting replication in many cases, allowing for deployment across medium- or large-scale companies; cost is usually the most major disadvantage.

Web application firewall depending on the host

Host-based web application firewalls (HWAF) are available as web server modules. It is a substantially less expensive alternative than hardware-based WAFs, which are designed for modest web applications. The majority of software WAFs are designed to be easily integrated with popular web servers. However, because host-based WAF depletes the resources of your application server, it can cause performance issues. In addition, keep in mind that some web server assaults can escape WAF and deactivate its operations from within, such as when a malicious file is put on the server directly via unprotected file transfer channels.

Web application firewall in the cloud

Cloud-based web application firewalls offer the same advantages as other software-based WAF solutions, such as cheap cost and the absence of on-premises resources to administer. When you don’t want to limit your performance possibilities or avoid a system that requires maintenance, cloud-based solutions are an ideal choice. Cloud service providers can supply a limitless pool of hardware with skilled setup and maintenance. However, the service costs may become too expensive at some point, or you may want a powerful tailored solution depending on your physical appliance.

WAF blacklist vs. allowlist WAF vs. hybrid WAF WAFs can function in various paradigms, including blacklist (negative security), whitelist (positive security), and hybrid security.

The blacklist paradigm protects the web application from known attacks or specific signatures, preventing assaults that exploit known flaws or vulnerabilities. The disadvantage of this strategy is that, due to the high percentage of zero-day assaults, all earlier blacklists became obsolete the instant they were created.

The whitelist paradigm, like signatures, applies logical decision-making and allows traffic that fits certain criteria; this means that requests from specific URLs may be accepted while all others are denied. The model’s weakness is the additional maintenance required each time a new application feature is introduced. To classify the new application behavior as “healthy,” you will most likely need to fine-tune the WAF basic rules and expand an allowlist.

As the name implies, the hybrid approach employs both the blacklist and whitelist models.

The difference between a web application firewall and a network firewall

The distinction between a network firewall and a web application firewall may appear ambiguous, yet there are significant differences between the two. It is critical to understand how different types of firewalls affect security and usability.

Network firewall applications control all access to local network resources, acting as gatekeepers between the local network and the Internet. Network firewalls have rules in place that decide which web traffic is permitted. These security solutions, like WAF, can be hardware or software-based.

As previously stated, web application firewalls are intended to monitor traffic entering and exiting an online application. Individually, the illicit traffic is reviewed and then filtered based on whether it is regarded detrimental or not. Because of the changeable nature of WAFs and the various settings that can be used, they are frequently used by enterprises that provide internet-based services.

Intrusion prevention system vs. web application firewall (IPS)

Web application firewalls and intrusion prevention systems are vital components of digital security, but they perform different functions in protecting digital assets.

IPS solutions are not designed to understand the underlying application, which means they are not designed to check for everything classified as an attack on the web application; the attack must trigger specified parameters for a response to be triggered. On the other hand, WAF is designed to detect and block several attack techniques against a web application, but, unlike IPS, they do not just scan all traffic that occurs.

Any firm that already has an IPS should think about adding a WAF to supplement the security solution.

Benefits of web application firewalls and final remarks

Web application firewalls respond intelligently (depending on web security settings) to potential threats to your network. In addition, WAFs are designed to protect your network from unknown threats, which means that deploying this solution can save your company from zero-day threats, security vulnerabilities, SQL injections, cross-site scripting assaults, and other forms of threats.

When bot attacks or high traffic events occur, well-developed WAFs take mitigation measures. Thus, WAF will maintain “clean” application traffic while fighting all harmful data flows.