What is a Web Application Firewall (WAF)?

Websites are exposed to a lot of threats. Malware injections, plugin vulnerabilities, distributed denial of service (DDoS) attacks, brute force attacks, and many other scary possibilities exist. Without a Web Application Firewall (WAF) or other security measures, you’re leaving your WordPress site open to data loss and other serious repercussions. When securing your website, a WAF is one of the best types of protection you can implement.

What is a Web Application Firewall (WAF)?

A web application firewall (WAF) helps protect a company’s web applications by inspecting and filtering traffic between each web application and the internet. A WAF can help defend web applications from attacks such as cross-site request forgery (CSRF), cross-site scripting (XSS), file inclusion, and SQL injection.

A WAF can be especially beneficial to a company that provides an e-commerce site, online financial services, or any other type of web-based product or service involving interactions with customers or business partners. In these cases, WAFs can be especially useful in preventing fraud and data theft. However, since a WAF is not designed to ward off all types of attacks, it works best as part of a suite of tools that support a comprehensive application security program.

How does a WAF work?

A web application firewall (WAF) intercepts and inspects all HTTP requests using a security model based on a set of customized policies to weed out bogus traffic. WAFs block bad traffic outright or can challenge a visitor with a CAPTCHA test that humans can pass but a malicious bot or computer program cannot.

WAFs follow rules or policies customized to specific vulnerabilities. As a result, this is how WAFs prevent DDoS attacks. Creating the rules on a traditional WAF can be complex and require expert administration. The Open Web Application Security Project maintains a list of the OWASP top web application security flaws for WAF policies to address.

WAFs come in the form of hardware appliances, server-side software, or filter traffic as-a-service. WAFs can be considered as reverse proxies i.e. the opposite of a proxy server. Proxy servers protect devices from malicious applications, while WAFs protect web applications from malicious endpoints.

Types of Web Application Firewalls

There are three primary ways to implement a WAF:

• Network-based WAF – usually hardware-based, it is installed locally to minimize latency. However, this is the most expensive type of WAF and necessitates storing and maintaining physical equipment.
• Host-based WAF – can be fully integrated into the software of an application. This option is cheaper than network-based WAFs and is more customizable, but it consumes extensive local server resources, is complex to implement, and can be expensive to maintain. The machine used to run a host-based WAF often needs to be hardened and customized, which can take time and be costly.
• Cloud-based WAF – an affordable, easily implemented solution, which typically does not require an upfront investment, with users paying a monthly or annual security-as-a-service subscription. A cloud-based WAF can be regularly updated at no extra cost and without any effort on the part of the user. However, since you rely on a third party to manage your WAF, it is important to ensure that cloud-based WAFs have sufficient customization options to match your organization’s business rules.

Attacks that WAFs prevent

Web Application Firewall security can prevent many attacks, including:

• Cross-site Scripting (XSS) – Attackers inject client-side scripts into web pages viewed by other users.
• SQL injection – Malicious code is inserted or injected into a web entry field that allows attackers to compromise the application and underlying systems.
• Cookie poisoning – Modification of a cookie to gain unauthorized information about the user for purposes such as identity theft.
• Unvalidated input – Attackers tamper with HTTP requests (including the URL, headers, and form fields) to bypass the site’s security mechanisms.
• Layer 7 DoS – An HTTP flood attack that utilizes valid requests in typical URL data retrievals.
• Web scraping – Data scraping is used for extracting data from websites.

Why is a Web Application Firewall important?

A WAF is important for the growing number of enterprises that provide products over the Internet – including online banking, social media platform providers, and mobile application developers – because it helps prevent data leakage. A lot of sensitive data, such as credit card information and customer records, is stored in back-end databases that are accessible through web applications. Attackers frequently target these applications to gain access to the associated data.

Banks, for instance, might use a WAF to help them meet the Payment Card Industry Data Security Standard (PCI DSS), which is a set of policies to ensure that cardholder data (CHD) is protected. Installing a firewall is one of the 12 requirements of PCI DSS compliance and applies to any enterprise that handles CHD. Since many companies employ mobile applications and the growing Internet of Things, an increasing number of transactions take place at the application layer using the web. For this reason, a WAF is an important part of a modern business’s security model.

When it comes to an enterprise security model, a WAF is most effective in conjunction with other security components, including IPSes, IDSes, and classic or next-generation firewalls (NGFWs).

Who uses Web Application Firewalls?

Given how common and complex cyberattacks have become, most organizations find themselves struggling to defend themselves from malicious attacks. E-commerce businesses, healthcare organizations, online financial services, and many others face an ongoing barrage of data theft and fraud threats. This can leave any brand open to possible regulatory discipline and compromised consumer trust.

WAFs are an important addition to a suite of tools to address these problems. A web application firewall can fortify an application security program with an essential extra layer of defense. WAFs can also help security professionals maintain more control. Security teams can monitor based on predetermined rules and guidelines to alert for possible attacks in progress.

Conclusion

A Web Application Firewall (WAF) is a vital security measure for protecting web applications from a wide array of cyber threats. Utilizing a positive security model, the WAF only permits known, trusted traffic, effectively blocking all unrecognized, potentially malicious activities. By analyzing, filtering, and blocking malicious traffic in real-time, a WAF enhances overall security, supports compliance with regulatory standards, and facilitates incident response and threat analysis. As cyber threats continue to evolve, WAFs provide a dynamic and adaptable line of defense, ensuring the integrity and continuity of web services.