Guide to Web Form Security

From collecting information to completing orders, web forms provide a wealth of opportunities to connect with and learn about consumers. Unfortunately, these forms can be as risky as they are helpful. Not only are they incredibly vulnerable to attacks, but they are also frequently overlooked when developing website security solutions.

With data from market research firm Clutch suggesting that 86 percent of users complete at least one web form per week, it's clear that there's a strong need for robust security initiatives designed specifically with these vulnerable forms in mind. Equipped with the most comprehensive security solutions, you can keep malicious parties at bay. Below, we outline the web form security practices that help reduce risk and protect user data.

Why does web form security matter?

Web forms are far more vulnerable than most people realize. Much of this risk stems from their increased exposure as compared to other website applications. This, in turn, can grant malicious parties shockingly easy access to customer data. Oversights can also open the door to devastating attacks, such as form action hijacking.

Secure form data is also crucial from a legal standpoint. Today's businesses are responsible for keeping consumers' personal data protected, especially as they interact with these consumers in online spaces. Even if you manage to avoid most attacks, your failure to implement the necessary security protocol could lead to a variety of compliance concerns.

Compliance aside, a lackluster approach to web form security leaves you vulnerable to these common attacks:

• Cross-scripting attacks. While cross-site scripting (XSS) can involve a variety of web applications, web forms are a common vector. In web forms, attackers can insert malicious JavaScript directly into input fields such as contact forms, search boxes, or comment fields, which is then processed, stored, or displayed by the site and executed in users’ browsers. If successful, these attacks can capture form respondents' keystrokes, obtain their cookie information, or send them to malicious websites.

• SQL injection attacks. Structure Query Language (SQL) injections occur when spammers manipulate SQL code. This allows them to view, modify, or even delete data. This is a common approach to acquiring sensitive information. It's one of the internet's oldest attacks, and yet, it also remains one of the most dangerous.

• Cross-site request forgery. If users are forced to complete unwanted actions on web forms or other applications, they may be unwittingly involved in cross-site request forgery (CSRF) attacks. With web forms, CSRF attacks work by tricking a logged-in user into unknowingly submitting a forged form that performs an action, such as changing account details or making a request, on the attacker’s behalf. Essentially, this approach involves tricking the user into performing unwanted actions on behalf of the attacker.

• Customer data breaches. Several types of attacks can ultimately grant malicious users access to valuable customer data. When form submissions are intercepted in transit, stored insecurely, or processed by vulnerable backend systems, attackers can exploit those weaknesses to extract personal data directly from form entries. Not only does a customer data breach place customers at risk, but it can also harm your reputation, making others think twice about interacting with your brand in the future.

Legal compliance

An ever-increasing array of data privacy laws govern how — and to what extent — web application security must be provided. Your need to comply with these laws may depend, in part, on where your business is based and how you operate.

As these regulations become more common, it’s important for website owners to adopt practices that facilitate compliant forms, regardless of geographic location. Currently, the most impactful data privacy laws include:

• GDPR. Few privacy initiatives have proven as groundbreaking as the EU's General Data Protection Regulation. After taking effect in 2018, GDPR transformed how we perceive data privacy and consumer rights online. This legal framework mandates robust privacy protection practices, which extend to web form security.

• CCPA & CPRA. Similar in many respects to GDPR, the California Consumer Privacy Act (CCPA) and its follow-up, California Privacy Rights Act (CPRA or CCPA 2.0), provide clear guidance on business obligations regarding the collection of consumer information.

• HIPAA. While it's been in effect for nearly three decades, the Health Insurance Portability and Accountability Act (HIPAA) continues to play a key role in determining how healthcare data is gathered and distributed. While embedded web forms can make it easier to collect patient health information and share it with authorized parties, many are not actually HIPAA compliant. Violations can lead to major penalties.

• PCI DSS. The Payment Card Industry Data Security Standard (PCI DSS) has brought a variety of key players from the payment industry together to ensure safe payments on a global scale. While PCI compliance is not enforced by the US government, PCI compliance is often built into agreements with merchant service providers. Therefore, failure to maintain compliance can lead to large fines and many other consequences.

How to secure a web form

Web form security initiatives closely resemble security protocols for other applications. No single intervention will guarantee form security, but a layered approach can help you avoid the most dangerous attacks. The following solutions will help keep your customers safe and your web forms compliant.

Use SSL/TLS certificates

Transport Layer Security (TLS), commonly still referred to as Secure Sockets Layer (SSL), is designed to produce secure connections between clients and servers. It centers around the concept of public key cryptography, in which a combination of private and public keys are called on to exchange data. These keys then make it possible to safely encode and decode data.

SSL certificates produce encrypted links between browsers and servers. They can be categorized based on the level of validation offered, with Extended Validation (EV) providing the most extensive coverage.

Web forms are one of the most common points where sensitive data enters a website. Without SSL/TLS certificates in place, information submitted through contact forms, checkout fields, login forms, or support requests can be intercepted in transit.

Encrypt your data

End-to-end encryption (E2EE) is non-negotiable for modern website security. High-level data encryption protects data in transit and at rest, reducing exposure during transmission and storage. With web forms, this means that sensitive information can only be decrypted by authorized parties, who are equipped with private keys. Content Delivery Networks (CDNs) can secure data in transit using TLS and improve performance, but true end-to-end encryption depends on how data is encrypted, handled, and stored on the server.

For web forms, encryption is especially important at both the submission and storage stages. Data entered into form fields should be encrypted as it travels to your server and, when applicable, encrypted again when stored in databases or sent to internal systems. Encrypting data protects form submissions from being exposed through network interception, compromised plugins, or unauthorized database access.

Validate and sanitize

Although they are not typically used as primary solutions for preventing SQL injections or cross-scripting attacks, input validation and sanitization can provide a valuable layer of defense.

Validation determines whether requests are authorized before revealing whether the data appears as expected. Sanitization involves a more active effort to ensure that security requirements have been met. Often, this means eliminating problematic characters.

Collect only what you need

In today's data-driven world, we're often inclined to collect as much information as possible. High volumes of data aren't always beneficial, however, and this can actually place website visitors at greater risk.

This principle is especially important for web forms, which are often designed to gather more data than is strictly required. Each additional field increases the volume of sensitive information you must protect and expands the potential impact of a breach. Limiting form inputs to only what is essential reduces both security exposure and compliance risk. As you determine what to collect and how, look to legal frameworks such as GDPR and CCPA for guidance.

Anonymize and obfuscate the data when possible

Simple efforts to anonymize data can pay huge dividends for web form security. A common and surprisingly effective solution involves the visual presentation of asterisks when users type sensitive details such as credit card information, driver's license numbers, or Social Security numbers to prevent someone from reading information on their screen.

Additionally, it's standard practice to mask passwords via asterisks. Often referred to as data masking, these solutions also may incorporate substitution or shuffling, which ensures that data has limited value to intruders.

Ask for consent

Today's most impactful data privacy laws mandate that businesses secure consent prior to collecting consumer information. Because web forms are often the primary method for collecting personal data, they must clearly communicate consent at the point of submission. Consent checkboxes, inline disclosures, and links to privacy policies within the form interface ensure that users understand how their data will be handled before they click “submit.”

An accessible privacy policy is just as important; many businesses display these in website footers so that they're always within easy reach. No matter how it's accessed, this policy should detail what types of information your website may collect, how and when this information could be used, and what steps you've taken to protect users from malicious parties.

Restrict file uploads

File uploads are a popular type of user input, in part because they are so convenient for website visitors. Unfortunately, they're also among the most problematic from a security standpoint. A single vulnerable upload form can be exploited to introduce malicious scripts, execute unauthorized commands, or distribute malware.

To maintain a secure environment, place strict limits on uploads. First and foremost: anonymous users should not be allowed to upload information — they must first secure permission.

Many of the strategies outlined above should provide additional protection. SSL certificates, for example, will secure traffic between the browser and the upload servers.

Next, limit file size to reduce the risk of Denial of Service (DoS) or Distributed Denial of Service (DDoS) attacks. Experts from the Open Worldwide Application Security Project (OWASP) also recommend listing allowed extensions and adjusting file names so that they're created by the application.

Use reCAPTCHA

Designed to limit spam, reCAPTCHA is a valuable tool capable of distinguishing between humans and bots. ReCAPTCHA is a specific form of CAPTCHA, which stands for Completely Automated Public Turing test to tell Computers and Humans Apart.

Google has released several types of reCAPTCHA solutions through the years; these are periodically updated to ensure that they are still capable of telling humans and bots apart, especially as bots become more sophisticated. Implementing reCAPTCHA directly on forms helps prevent bot-driven spam, credential stuffing, and mass submission attacks that can overload systems or exploit form logic.

To add reCAPTCHA to web forms, register with Google's reCAPTCHA admin. You can select v2 (featuring the well-known "I'm not a robot" checkbox) or v3, which uses a score to verify requests. Invisible reCAPTCHA badges are also available.

Require authentication

We've already discussed the importance of authentication and permission when uploading files, but this should also apply to many other types of form submission. Any forms that involve potentially sensitive data should be limited to authorized users. Consider implementing multi-factor authentication, which goes beyond simple passwords to provide an extra layer of security. Restricting form visibility and submission privileges significantly reduces the risk of unauthorized data exposure and malicious manipulation.

Use virus and malware protection

In recent years, many alarming viruses and malware attacks have been spread via web forms. These initiatives increasingly involve contact forms, with malicious players often finding clever strategies to work around CAPTCHA protocols and send harmful email messages.

Because web forms often feed directly into email systems, CRMs, or internal databases, any malicious script submitted through a form can spread across business systems. Scanning form submissions and uploaded files in real time helps prevent malware, phishing content, and exploit scripts from reaching downstream applications or staff inboxes.

As such, any web form security solution should also encompass comprehensive virus and malware protection. To achieve maximum security, implement a layered strategy encompassing virus and malware scans, a Web Application Firewall (WAF), and intrusion detection.

Protect your site with SiteLock

Ready to give your web forms a much-needed security boost? Look to SiteLock for advanced security solutions that keep malicious players out of the picture. Our malware scanner solution can promptly detect vulnerabilities, thereby preventing damage from SQL injections or XSS attacks. We're also pleased to provide WAF cloud security services, which are capable of distinguishing between legitimate visitors and malicious traffic.

As you determine which security solution is best capable of meeting your unique needs, feel free to discuss your situation with our experts. We'd be happy to point you in the right direction.

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