As cyberattacks continue to grow in complexity, businesses are looking for tools to harden digital security. There are two main options: network firewalls and web application firewalls (WAF). What, then, do you need to know about WAF vs firewall?
A cloud-based service, virtual appliance, or hardware appliance called a web application firewall (WAF) sits in front of online-facing apps and is a barrier against various harmful threats. Network firewalls, conversely, guard against unwanted access to computer networks. Network firewalls function by dividing a network’s protected area from its less secure area, preventing unwanted access.
What is a WAF?
A WAF is a firewall between users and web applications to track and analyze HTTP communication, blocking malicious traffic before it can reach users or web apps. It can be deployed in software, an appliance, or as a cloud-based security-as-a-service solution. Policies can be configured to the organization’s needs and updated as the web application evolves or as new threats emerge.
A traditional WAF uses an attack pattern database that lists known attacks, such as SQL injection or OSCI (Operating System Command Injection), and tries to recognize them in the traffic it receives. However, hackers are constantly creating new techniques to fool these detection systems. For this reason, a modern WAF must use a combination of technologies to detect and defend against advanced bot attacks effectively.
One of the challenges with traditional WAF technology is that it can be prone to false positives and alert fatigue, which causes security teams to reduce or turn off protections.
What is a Firewall?
Firewalls act like security guards that monitor your network’s traffic based on predefined rules. These rules assess the context of data packets to decide whether to allow them into a network or deny them. Without a firewall, your network, devices, and personal data are vulnerable to cyberattacks.
Network firewalls work at the network layer and analyze data packets using criteria such as source/destination IP, ports, protocols, etc. They look for malicious code to infect your devices or network and block the packets. Firewalls can be hardware-based or software-based, depending on the needs of your business.
On the other hand, web application firewalls work at the OSI model’s application layer and protect your web applications from attack vectors such as SQL injection, cross-site scripting (XSS), cookie manipulation, DDoS attacks, and file inclusion. They typically analyze and filter HTTP traffic to and from web applications, preventing these threats before they reach web servers and users.
WAFs can be hardware-based or software-based and can be deployed as a network appliance, a virtual firewall on-premises, or a cloud-based service. The best WAF for your business will depend on where your applications are deployed, their services, and your preferred deployment method. For example, do you prefer a solution that works with your existing security infrastructure, or do you want to take advantage of the performance and architectural flexibility that a cloud-based WAF offers?
How Do WAFs Work?
A WAF works by analyzing HTTP conversations between users and web applications. It detects and analyzes the GET and POST requests to determine if they are legitimate or malicious, and then takes action accordingly.
Depending on how the WAF is configured, it can protect against various attacks, including cross-site scripting (XSS), cross-site request forgery (CSRF), and SQL injection. A well-configured WAF can reduce the risk of downtime, data theft, and security breaches by blocking attacks at layer 7.
Your WAF type depends on your business needs and technical resources. It can be deployed as software, an on-premises appliance, or a cloud-based service. WAF policies can be configured using behavioral analysis, AI, application profiling, and custom rules.
A good WAF can reduce risk by implementing both blocklisting and allowlisting approaches. In a whitelisting approach, a WAF uses machine learning and behavior modeling algorithms to define what packets should be allowed through. By comparison, in a blacklisting approach, a WAF uses preset signatures against known vulnerabilities to define what packets should be blocked. A WAF also offers a hybrid model, which combines the two to provide an effective defense-in-depth security model for your web applications. In addition, a WAF can help you meet compliance requirements such as PCI DSS for enterprises handling cardholder data.
Which is Right For You?
Web application firewalls provide a layer of security that goes well beyond what traditional network firewalls, IDSes, and IPSes do. They monitor and protect against the most dangerous vulnerabilities, exploits, and threats that target a business’s web applications, including zero-day attacks, malware infections, impersonation, and other advanced threats.
A WAF analyzes HTTP conversations—specifically, GET and POST requests—to determine what is malicious or benign. Using rules deployed by an organization, the WAF decides how to respond to each request, which can include a variety of actions, such as granting access or blocking unauthorized activity. The organization maintains the rules, which can be based on some characteristics of each request, including approved characters, IP addresses, file types, and other aspects.
The rule set also includes a blacklisting approach, whereby the WAF denies all traffic that doesn’t match a specific pattern. This is more resource-intensive than whitelisting, but it is more precise and can prevent the unintentional blocking of benign traffic.
A WAF is an essential tool for any modern company’s security strategy. While a traditional firewall guards the perimeter and networks based on ports, protocols, and other characteristics, WAF zooms in to defend specific web applications from attack. It’s a key part of an in-depth defense strategy that can complement other technologies such as threat intelligence, behavioral analytics, and machine learning.