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How Does a WAF detect and respond to attacks?

by Mic Johnson

Nowadays a web application firewall should be an essential part of every business’s infrastructure. This single tool helps protect the application infrastructure from various cyber threats using numerous methodologies. This article explains how a WAF detects/prevents cyber-attacks.

What is a Web Application Firewall (WAF)?

In simple terms a WAF serves as a barrier between an application environment and the external online world. Here, the term “application” refers to your website or software.

Technically, it guards the seventh layer of the OSI model – that is, the application layer and covers the whole of the app infrastructure from trivial vulnerability exploits to large-scale DDoS attacks.

How a WAF detects and prevents cyber risks?

Typically, a Web Application Firewall works by monitoring HTTP traffic coming into your app and then decides whether to allow or block a request based on the rules it has been configured with. Examples of malicious attacks include SQL Injection, XSS, session hijacking, buffer overflow, DoS, and C&C communication.

For adequate protection without false positives or irrelevant traffic blocking, a WAF allows the creation of blacklist and whitelist rules to permit specific HTTP traffic to the site while blocking the rest. In this way, WAF allows customized security configuration for a website or app.

Here’s a quick review of the key WAF security features that constitute WAF detection and prevention strategies.

  • App profiling: WAF analyzes app structure, including URLs, values, allowed traffic requests, and permitted data types. Such profiling then enables the tool to detect and block anything unusual.
  • AI-based traffic pattern analysis: An AI-powered WAF monitors the usual traffic patterns for potentially safe or malicious behaviors, enabling the tool to detect and block any anomalous behavior.
  • Attack signatures database: WAF may use known malicious attack patterns/signatures databases, like the malicious IPs, server responses, or malicious request types, to detect unusual activities. However, this approach might not be helpful against novel attack patterns.
  • CDN (Content delivery network): Cloud-based WAF deployed on a network can offer a CDN for website caching and improving load times.
  • Customization: WAF allows setting up custom rules to permit a particular type of traffic. This customization ensures that only the permitted traffic is passed through, while blocking anything not allowed.
  • Correlation engine: Uses customization, attack signature analysis, traffic pattern analysis, and app profiling to analyze incoming traffic and block anything malicious.
  • DDoS protection: Cloud-based WAF redirects the traffic to the DDoS protection platform upon detecting a DDoS attack the redirection can handle large traffic volumes therefore preventing traffic reaching its intended target.

Proactive Bot Defense 

When it comes to bot management, WAFs can do a few things:

  • Detect bots by monitoring traffic and looking for certain patterns that are commonly associated with automated activity
  • Stop bots by blocking or throttling traffic from IP addresses that are known to send a high volume of automated requests
  • Identify bots by analyzing the behavior of individual requests and noting any anomalies (like a high number of requests coming from the same IP address within a short period of time)
  • Suspend or blacklist IP addresses that are determined to be bots

WAFs are important for businesses because they provide an extra layer of security that helps protect against common attacks like SQL injection, Cross-Site Scripting (XSS), malware and zero-day attacks. By using a fully managed WAF such as Indusface AppTrana, businesses can rest assured knowing that their web applications are better protected against these types of attacks.

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