A WAF functions best with other tools supporting a comprehensive application security program, whether deployed as software, an appliance, or a cloud service.
WAFs typically employ a ruleset that analyzes user responses to ward off attacks.
A WAF works via blacklisting and whitelisting – think of it as a bouncer that rejects terrible actors or a club’s dress code.
Prevents Malware Attacks
In addition to analyzing and blocking suspicious or malicious traffic, WAFs monitor outbound data to prevent sensitive information from leaking. They do this by parsing the HTTP data sent to or from a web application and analyzing it for malicious content or patterns.
The difference between WAF vs firewall is that firewalls provide barriers between internal and external network traffic. WAFs are designed to protect applications by targeting Hypertext Transfer Protocol (HTTP) application-level vulnerabilities. They do this by residing between web servers and users, examining their communication, and comparing the information with existing vulnerability databases.
It allows them to detect, block, and mitigate various threats, including cross-site scripting attacks, SQL injection attacks, CSRF attacks, bot mitigation, denial-of-service attacks, and more. To ensure that a WAF solution can protect your organization against these threats, it should be tested and configured correctly. You should also evaluate the in-house skills and capabilities required to manage the WAF solution effectively. A managed WAF with machine learning capabilities should be deployed to continuously learn and automatically manage policies and rules for the best results.
Prevents Cross-Site Scripting (XSS) Attacks
A WAF prevents XSS attacks by inspecting the HTTP conversations between web applications and their back-end databases. Specifically, it analyzes GET and POST requests to detect and block data that contains common XSS attack signatures. It also sanitizes potentially malicious data to reduce the impact of an attack.
Since a WAF operates at the application layer, it can protect against attacks that traditional firewalls cannot. WAF solutions should be used with network firewalls for a comprehensive security solution.
A WAF can be a software or hardware appliance installed locally to minimize latency or deployed in the cloud as a fully managed service. A host-based WAF requires extensive local server resources and requires management and maintenance.
While the unique benefits of WAF include its ability to protect against threats that aren’t addressed by network solutions, it’s important to note that evolving attacks can still compromise this security tool. As attackers discover that a particular type of attack is blocked, they quickly devise new methods for evading detection by the WAF.
Prevents SQL Injection Attacks
Web application firewalls (WAF) protect web applications and servers from attacks at the application layer. A WAF sits before a website to analyze and filter all HTTP communication between external users and the web application, detecting and blocking malicious requests.
A WAF looks for patterns that indicate an attack by inspecting and filtering all input data. It includes SQL commands (insert, update, and delete) and other suspicious characters, operators, and comment symbols such as>, |, &, *. It also checks for the sanitization of data and the use of prepared statements and stored procedures to prevent SQL injection attacks.
Most WAFs are rules-based, either provided by the vendor for out-of-the-box usage or customized by users. While these rules help provide protection, they demand high maintenance and are prone to false positives that attackers can bypass with simple techniques like mixed-case letters or SQL commands not filtered by the WAF. Combining a WAF with other security measures like input sanitization and coding best practices is essential.
Prevents Cross-Site Request Forgery (CSRF) Attacks
Many web applications use back-end databases to store customer records or credit card information. When these applications are compromised, attackers can use a technique known as cross-site request forgery (CSRF) to steal sensitive data.
WAF can prevent CSRF attacks by filtering out the fake requests that hackers send to a website. These fake requests can look legitimate, such as a transfer of money from your bank account. This trickery happens because an attacker has a user-id and password for your online bank account, which allows them to pretend to be you.
Most WAF solutions analyze application behavior and structure to detect malicious patterns. Some advanced WAF solutions utilize artificial intelligence and machine learning to monitor traffic, characterize baselines, and identify anomalies. This context-based security can catch sophisticated attacks that elude generic firewalls. In addition, most WAF solutions enable organizations to define and instantly apply security rules unique to their business and app logic. It allows a degree of customization that avoids blocking legitimate traffic. Depending on the WAF implementation, these rules or policies may need to be updated periodically to address new vulnerabilities.
Prevents Hackers from Accessing Data
The WAF protects data by blocking or rate-limiting incoming traffic that may seem to be suspicious. It is conducive for businesses that must safeguard customer data, like an e-commerce site or online financial service.
While a WAF can prevent many attacks, it is not designed to avoid all threats. Moreover, hackers can use machine learning to create new forms of attack behavior that the WAF can’t detect. It makes a continuous game of cat and mouse in which the attacker devises new ways to evade detection while the WAF updates its rules to ward off the latest vulnerabilities.
A WAF can lighten the burden of web application security teams by automating a significant portion of their testing activities. It frees up security resources to focus on other vital security areas, such as monitoring and logging. Cloud-based WAFs provide additional benefits by not needing the technical team to manage hardware and software but offer similar functionality that on-premises hardware-based WAFs do. They also help reduce costs by not requiring the purchase or management of an expensive hardware appliance.