Enterprise web applications are designed to handle high volumes of client-side HTTP requests each day. These requests might induce any number of responses from the underlying server, such as the retrieval, expansion, or modification of content (including files, data sets, and more). This data-centric client-server interaction is what drives online businesses forward – and it’s also what exposes these enterprises to major security threats.

Web Application Firewalls (WAFs) are critical components of enterprise cybersecurity infrastructure designed to identify and block threats targeting web application servers. Unlike network firewalls, WAFs focus specifically on application-layer threats. Their purpose is to protect enterprise web applications (and entire websites) from attack vectors like SQL injection (SQLI), cross-site scripting (XSS), unrestricted file upload, and more.

How do WAFs work?

WAFs effectively operate as reverse proxies for web applications and websites. They inspect incoming and outgoing traffic for potential threats.

All WAF implementations serve the same high-level purpose in defending enterprise web applications. However, the specific behavior of any given WAF is determined by the WAF solution provider and the enterprise implementing that solution into their network. WAFs can be configured with enterprise-use-case specific rule sets, varying levels of primitive or advanced behavioral heuristics, and even artificial intelligence (AI) threat detection capabilities.

When malicious requests for any configuration are detected, the WAF blocks those requests from reaching the application server or “sanitizes” them to neutralize the malicious input. Afterwards, it typically logs the threat incidents where human security teams can analyze them. WAFs can also be configured to redirect malicious requests to decoy or “honeypot” servers, which exist to intentionally trap and gather information on cyberattacks.

Where are WAFs deployed?

WAF deployments occur as close as possible to where HTTP requests first enter enterprise infrastructure. This reduces latency and ensures threats are blocked early (before they can reach more sensitive network edge locations). Specific deployment strategies differ from enterprise to enterprise.

Present-day deployments are most often cloud-based, hosted on either public or private cloud tenant infrastructure. However, it’s still common for enterprises to carry out WAF deployments in on-premises servers for more granular control of their solution. This latter deployment method is often a requirement in highly regulated industries like finance or healthcare.

Modern DevOps environments can also allow for containerized deployments alongside web application services hosted in Kubernetes or virtual machines.

What are some major threats WAFs help prevent?

Earlier, we mentioned some of the primary threat types WAF solutions protect enterprise applications against: SQLI, XSS, and unrestricted file upload. We’ll take a closer look at each threat below and understand how WAFs typically mitigate these attacks.

SQL Injection (SQLI)

SQLI attacks occur when a client-side attacker successfully exploits unsecured entry points (like login forms, search bars, or URL parameters) in a web application to manipulate or retrieve data stored on the application server. The idea is to induce the underlying SQL dataset into interacting with data on the attacker’s behalf, circumventing the application’s intended data access controls.

A well-configured WAF will detect SQLI query strings – or any tampering with application input parameters – before the HTTP request carrying that information reaches the application’s database. WAFs are by no means the only defense against SQL injection attacks, but they’re extremely effective at blocking and reporting them in real-time.

Cross-Site Scripting (XSS)

XSS attacks occur when a client-side threat actor injects malicious scripts into legitimate web pages. These attacks are designed to exploit weaknesses in how web applications handle user input – specifically when that input loads in a user’s browser without being sanitized or encoded correctly. Successful XSS attacks can have a wide range of outcomes, including data theft (session cookies, login credentials, etc.), session hijacking, defacement (in the case of websites), redirection of users to some malicious site, or – in extreme cases – direct delivery of malicious code onto the victim’s machine.

WAFs play an important role in preventing XSS attacks by stopping malicious scripts from being injected into web pages viewed by others. They usually accomplish this by inspecting inbound requests for known attack patterns or by analyzing requests for suspicious characteristics (such as malformed characters or script tags).

Unrestricted File Upload

Unrestricted file upload is an attack vector which broadly encompasses any scenario where a web application permits file uploads without properly validating or sanitizing them. Attackers can upload web shells, scripts, or malware-infected files designed to execute on the application server. This can lead to remote code execution (RCE), data theft, denial of service (DoS), or complete system compromise.

Since file uploads are passed to web application servers in HTTP requests, WAFs are well positioned to enact file upload validation and sanitization policies. They can intercept files from HTTP requests and root out malicious content via stringent virus/malware scanning and content verification.

Defending enterprise web applications with Cloudmersive’s AI WAF

Cloudmersive’s AI-powered web application firewall uses artificial intelligence to identify and block threats based on real-time patterns. This effectively counters AI-generated attack traffic, which is increasingly common in today’s booming AI landscape.

This solution leverages Cloudmersive’s Security API and Advanced Virus Scan API under the hood to defend against SQLI, XSS, and unrestricted file upload threats, along with other threats like insecure deserialization and server-side request forgery (SSRF). The Advanced Virus Scan API combines signature-based malware detection with robust content verification policies to prevent both established and zero-day threats alike.

Cloudmersive’s AI WAF can be deployed flexibly on public cloud, private cloud, and on-premises infrastructure to accompany enterprise web applications according to specific enterprise needs.

Final Thoughts

Web application firewalls play a crucial role in protecting modern enterprise web applications from client-side threats. They bridge the gap between traditional network security and application-layer vulnerabilities, and they defend against a broad attack surface with numerous unique policies.

For expert advice regarding Cloudmersive’s AI WAF solution for enterprises, please feel free to reach out to a member of our team.