6 Web Application Security Best Practices

Understanding Modern Web Applications

Modern web applications power e-commerce platforms, customer relationship management (CRM) systems, internal line-of-business tools, application programming interfaces (APIs), and more. They are intricate, interconnected, and fraught with hidden attack surfaces.

At a high level, modern web apps consist of multiple components:

• Client-side: The presentation layer, is constructed with various combinations of HTML, CSS, and JavaScript libraries to build dynamic user interfaces (UIs).
• Server-side: The business logic layer, with server-side application code and services that process client requests, execute business logic, generate responses, and expose APIs.
• Database: A data storage layer, often composed of several distributed database systems, where web applications store and manage business and customer information.
• Infrastructure: Simple web applications are often deployed to a single server or VM. Complex cloud-based applications may span across multiple virtual machines (VMs), serverless compute functions, containers, and managed databases.
• Services: Web applications may rely on various third-party services, including content delivery networks (CDNs), message queues, search engines, and monitoring or logging tools.
• Security: Modern web applications often rely on advanced security solutions such as identity and access management (IAM) systems, network firewalls, intrusion detection systems (IDS), and web application firewalls (WAFs) or WAFaaS.

6 Web Application Security Best Practices

Here are six essential practices to fortify web applications against attack:

#1: Input Validation and Sanitization

Injection attacks come in a variety of forms, including:

• SQL injection
• Command injection
• XSS attacks

Protecting against these and other forms of injection attacks requires careful input validation and sanitization. User input must be validated to ensure that it conforms to expected formats and data types. For instance, data input should be checked against allow lists, which permit valid values, or block lists, to deny known harmful patterns.

Sanitization techniques include removal or escaping of special characters, and length checking/trimming to limit character input size. Web applications must also leverage prepared statements or parameterized queries for database interactions to prevent SQL injection attacks.

#2: HTTPS

HTTPS encrypts information sent between the user’s browser (the client) and the web application (the server), playing an important role in the authentication and protection of data.

Use of Transport Layer Security (TLS) version 1.3+ encryption algorithm ensures that.

Even if an attacker successfully intercepts data packets, they won’t be able to decipher the data without the decryption key. Obtaining valid Secure Sockets Layer (SSL) / TLS certificates from a trusted Certificate Authority (CA) prevents potential threats like eavesdropping, man-in-the-middle (MitM) attacks, and session hijacking.

#3: Data Encryption

Web applications commonly store sensitive data, including:

• Proprietary company information
• Client data

Encryption ensures the security of this data. The use of robust data encryption algorithms, such as Advanced Encryption Standard (AES) and Rivest-Shamir-Adleman (RSA), ensure that even if an attacker gains access to the storage device or database, they won’t be able to read it.

Both AES and RSA may be used at the field level to protect individual files or data fields in a database, at the volume level to encrypt entire storage devices, or at the database level to automatically encrypt and decrypt data held in database storage volumes.

#4: The Principle of Least Privilege (PoLP)

Least privilege is a fundamental concept in computer security. The PoLP recommends granting users the lowest possible permissions required to perform their intended tasks.

In the context of web applications, the PoLP applies to subsystems, automated services and user accounts that comprise the web application system. Whether by way of code or configuration, these components must only be granted the minimal permissions required to perform their functions, and no more.

This reduces the potential for damage spreading in the event a subsystem is breached and prevents privilege escalation if a user or service account becomes compromised during an incident.

#5: Output Encoding

Web applications may receive data input from a user and then re-display that input within the pages of the application. A familiar example of this is user comment functionality.

XSS is a common form of injection attack that exploits security vulnerabilities in user input vectors like comment forms. Output encoding protects web applications by encoding data in a way that prevents malicious scripts from being executed if present in user-supplied data.

For example, output encoding can convert the angle bracket characters < and > so they are displayed as plain text rather than executable HTML instructions, thus neutralizing <script> tags containing potentially malicious JS code.

#6: Access Control & Authentication

Web applications often feature a variety of user account types, and rely upon various authentication methods for access to them. Securing the roles, permissions and authentication processes for these accounts reduces the risk of a data breach.

Authentication mechanisms, including strong password policies, use of multi-factor authentication (MFA), and account lockout policies help to verify and secure user identities.

Implementation of authorization controls restricts unauthorized access to sensitive data and functions, such as

• Attribute-based access control (ABAC)
• Role-based access control (RBAC)
• Mandatory access control (MAC)

The combination of robust authentication and authorization controls enforces the least privilege principle, lowers the risk of data breaches, limits access to accounts with elevated permissions, and facilitates audit trails of user activity within the application.