Types of Web Application Firewalls (WAFs): Cloud vs. Software vs. Hardware

Websites face constant threats from cybercriminals exploiting vulnerabilities to gain unauthorized access, steal data, or disrupt services. A  Web Application Firewall (WAF) is a critical security solution that protects web applications by  monitoring, filtering, and blocking malicious HTTP traffic before it reaches the server. 

WAFs operate at the application layer (Layer 7) of the OSI model and function as a  reverse proxy intercepting traffic and applying security rules to prevent attacks like: 

• SQL Injection 
• Cross-Site Scripting (XSS) 
• Distributed Denial-of-Service (DDoS) Attacks 
• Zero-Day Vulnerabilities 

Organizations can deploy different types of WAFs depending on their infrastructure, security needs, and compliance requirements. Below, we explore the three main categories of WAFs: Cloud-Based, Software-Based (Host-Based), and Hardware-Based (Network-Based). 

Learn more about WAF functionality in our blog: How a WAF Works.

Types of Web Application Firewalls

1. Cloud-Based WAF

A Cloud-Based WAF is a fully managed security solution provided by third-party vendors. It is deployed in-line or as an API-based, out-of-path (OOP) service, offering scalability, ease of deployment, and continuous updates. 

Who Should Use It? 

• Businesses of all sizes – from small startups to large enterprises. 
• Organizations using multi-cloud environments or seeking a hassle-free, subscription-based model. 

Advantages 

• Scalable and cost-effective – Operates on a subscription model, eliminating hardware costs.
• No maintenance required – Security updates are managed by the provider.
•  Centralized management – Protects multiple applications across different environments.
• Rapid deployment – Easy to implement without disrupting existing infrastructure. 

Disadvantages 

•  Potential latency – Traffic may be rerouted to the provider’s servers, adding delay.
• Third-party reliance – If you do not subscribe to a managed WAF, security updates, threat intelligence and app specific policy tuning need to be take care of internally. 

Examples of Cloud-Based WAFs 

• AppTrana WAAP 
• Cloudflare WAF 
• AWS WAF 
• Akamai App & API Protector 
• Imperva Cloud WAF

2. Software-Based (Host-Based) WAF

A Software-Based WAF is a virtual appliance or agent installed on a server, virtual machine, or cloud environment. It offers customizable security policies and is suitable for organizations that require greater control over their web security. 

Who Should Use It? 

• Businesses with on-premise or cloud applications requiring in-depth security controls. 
• Organizations with in-house expertise to manage and configure security policies. 

Advantages 

• H️ighly customizable – Security rules can be tailored to specific application needs.
• Lower cost than hardware-based WAFs – No need for physical infrastructure.
• Works in containerized environments – Compatible with Docker, Kubernetes, and microservices. 

Disadvantages 

• Resource-intensive – Uses server resources, potentially affecting performance.
• Complex deployment – Requires manual configuration and ongoing updates.
• User-managed updates – Security patches and rule updates must be handled internally. 

Examples of Software-Based WAFs 

• ModSecurity (open-source) 
• Naxsi (open-source) 
• NetScaler Web Application Firewall

Compare cloud and on-premise WAFs to see which solution best fits your security needs.

3. Hardware-Based (Network-Based) WAF

A  Hardware-Based WAF is a physical appliance deployed on-premise, typically installed between the web server and external traffic sources. It provides low-latency protection and full control over security policies, making it ideal for large enterprises with high-performance security requirements. 

Who Should Use It? 

• Enterprises and government organizations needing high-performance and air-gapped security. 
• Businesses handling sensitive data that require strict compliance (e.g., finance, healthcare). 

Advantages 

• Low latency – Inspects traffic locally, reducing delays.
• Highly customizable – Security policies can be fine-tuned.
• Complete control – No third-party involvement in security management. 

Disadvantages 

• High upfront cost – Requires purchasing, installing, and maintaining hardware.
• IT expertise required – Needs in-house security professionals for management.
• User-managed security updates – Patch management is handled internally. 

Examples of Hardware-Based WAFs 

• Barracuda Web Application Firewall 
• F5 Advanced WAF 
• Fortinet FortiWeb 
• Radware AppWall 

Alternative WAF Classifications

1. Blocklist WAF (Negative Security Model) – Blocks known attack patterns based on preconfigured signatures. 

Example: Prevents requests from malicious IP addresses or bots.

2. Allowlist WAF (Positive Security Model) – Only allows traffic that meets pre-approved security rules. 

Example: Restricts access to trusted users or geolocations. 

3. Hybrid WAF – Combines both blocklist and allowlist methods to enhance protection. 

Key Features to Look for in a WAF 

When selecting a WAF, consider these essential security features:

• Threat Intelligence & Automatic Updates – Cloud WAFs offer real-time threat protection.
•  DDoS Mitigation – Protection against application-layer DDoS attacks.
• API Discovery & Protection – Identifies and secures exposed APIs.
• Machine Learning & Behavioral Analysis – Detect anomalies in traffic patterns.
• Compliance Support – Helps meet PCI-DSS, HIPAA, and GDPR requirements.
•  Integration with Security Tools – Works alongside DAST, SIEM, IDPS, and other security platforms. 

Before choosing a WAF, ensure it has these critical security features: Key Features to Look for in a WAF.

Comparison Table: Cloud vs. Software vs. Hardware WAFs 

Feature	Cloud-Based WAF	Software-Based WAF	Hardware-Based WAF
Deployment	Hosted by third-party providers	Installed on a local/cloud server	Physical appliance near the server
Customization	Limited if you do not have managed offering	High	Very High
Cost	Subscription-based, low upfront	Lower than hardware-based	High upfront & maintenance costs
Performance	May introduce latency	Uses server resources	Low latency
Maintenance	In-house unless you take a managed plan	User-managed	Requires in-house maintenance
Scalability	Highly scalable	Moderate	Low scalability

 

Conclusion 

Choosing the right Web Application Firewall (WAF) depends on an organization’s infrastructure, security needs, and budget: 

• For cost-effective, scalable security → Choose a Cloud-Based WAF
• For customized security in virtual environments → Choose a Software-Based WAF
• For high-performance, on-premise protection → Choose a Hardware-Based WAF 

Each WAF type plays a crucial role in defending against web application attacks, ensuring compliance, and maintaining business continuity.