Insecure Design: A Complete Guide

Imagine you're building a house. In the design phase, you decide on the layout, structure, and materials. You choose the number of rooms, where the doors and windows will go, and what kind of locks and security systems you'll install. 

Let's say you overlook some critical aspects during the design phase. You forget to include a lock on the back door. You chose windows that you liked aesthetically, but they don't close securely. For the foundation, you chose concrete slabs over poured concrete, which are more prone to cracking and make your plumbing less accessible. 

Once the house is built, these design flaws create vulnerabilities and potential problems. Even if you hire the best builders and use the finest materials for construction, the house is still fundamentally insecure because of the flawed design choices made at the beginning.

Insecure software design is similar to building a house with these kinds of flaws. Suppose security isn’t considered from the start. In that case, the resulting system will have exploitable vulnerabilities, just like a poorly designed house is accessible for burglars to break into or prone to collapse.

What Is Insecure Design in Software Development?

Insecure design refers to flaws or weaknesses in a software system's architecture, design, or logic that malicious actors can exploit. If security isn’t top-of-mind during this planning period, these foundational decisions can create systemic vulnerabilities that are difficult to rectify later in development.

Common examples of insecure design include:

• Failure to enforce security policies and principles.
  
  
• Inadequate or improperly implemented access controls.
  
  
• Insufficient validation of user inputs.
  
  
• Overly complex or unnecessary features that increase the attack surface.

The OWASP Top 10 is a widely respected list of critical app security risks maintained by the Open Web Application Security Project (OWASP). In its 2021 update, the concept of insecure design was formally recognized and included in the list. 

By emphasizing the importance of secure design, OWASP aims to encourage developers and organizations to adopt a proactive approach to security, addressing potential vulnerabilities early in the development lifecycle. The inclusion serves to raise awareness among developers, architects, and other stakeholders involved in the software development process about the significance of secure design principles and practices.

Insecure Design Example 

One of the main reasons insecure design was added to the OWASP Top 10 was the growing prevalence of design flaws, which led to numerous security incidents. One of the most well-known examples is the 2017 Equifax data breach and ensuing settlement. 

Equifax, an international credit reporting giant, suffered a significant data breach, exposing the personal information of approximately 147 million people. This breach resulted from various factors, including insecure design, poor patch management, and generally inadequate security practices. 

The breach was primarily due to an unpatched vulnerability in the Apache Struts web application framework, which Equifax was using. The vulnerability (CVE-2017-5638) was well-known, and a patch had been available for several months before the breach occurred. 

However, Equifax didn't apply it on time.

Another cause of the breach was the Equifax network architecture’s lack of proper segmentation. This meant that once attackers gained access through the initial vulnerability, they could move laterally across the network relatively easily, accessing sensitive databases without encountering significant barriers.

The breach went undetected for several months, indicating that Equifax's logging and monitoring mechanisms were also inadequate. Proper design and implementation of these systems could have detected the intrusion much earlier, minimizing the damage.

As a result, Equifax faced significant financial penalties, including a settlement of up to $700 million. Additionally, the company incurred substantial costs related to reputational damage, incident response, legal fees, and efforts to improve security measures.

Common Causes of Insecure Design Vulnerability

Insecure design can manifest in various ways, often leading to significant vulnerabilities that attackers can exploit. OWASP lists over 40 common vulnerabilities and exposures (CVEs) related to insecure design. Some of the most common missteps and architectural flaws that lead to insecure design include: 

• Lack of proper input validation: Failing to validate or sanitize user inputs can lead to injection attacks (SQL injection, cross-site scripting, etc.).
  
  
• Insufficient authentication and authorization: Weak or flawed mechanisms for verifying user identities and granting permissions can allow unauthorized access control.
  
  
• Poor session management: Insecure handling of user sessions can lead to session hijacking and other exploits.
  
  
• Inadequate error handling and logging: Failing to handle errors securely and not logging security-relevant events can provide attackers with valuable information or leave security incidents undetected.
  
  
• Insufficient data protection: Not properly protecting sensitive critical data at rest and in transit can lead to data breaches.
  
  
• Overly complex or unnecessary features: Including unessential features in the core functionality can increase the attack surface and introduce vulnerabilities.
  
  
• Lack of security in the development lifecycle: Not integrating security controls and testing throughout the software development lifecycle (SDLC).
  
  
• Insufficient threat modeling: Not adequately identifying and mitigating potential threats during the design phase.

How to Prevent Insecure Design Vulnerabilities 

Avoiding security vulnerabilities in application design starts with prioritizing application security in the earliest stages of development. Understanding and integrating security requirements early in the design phase is essential. Identifying security requirements from the beginning and using methodologies such as threat modeling– a systematic process for identifying, evaluating, and addressing potential security threats to a system or application—can help analyze potential threats effectively.

Adopting secure design principles is fundamental. The principle of least privilege—a security concept that involves granting users or systems the minimum level of access or permissions necessary to perform their tasks—should be applied. 

Defense in depth is another vital security strategy for avoiding insecure design. It involves implementing multiple layers of protective measures to safeguard against failures or breaches at various levels. Systems should be designed to fail securely, maintaining security even when errors occur. Separating duties by dividing critical tasks among multiple users or processes can prevent single points of failure or abuse.

Another key strategy is following secure coding practices. Input validation and sanitization are crucial to preventing injection attacks, while output encoding helps mitigate cross-site scripting (XSS) attacks. Employing robust encryption methods ensures that sensitive data is protected in transit and at rest. Implementing robust authentication mechanisms and ensuring proper authorization checks are essential to maintaining security. Following guidelines and standards from organizations like OWASP, NIST, and ISO ensures adherence to industry best practices.

Regular security reviews and testing should be conducted throughout the development lifecycle. Peer code reviews can help identify potential security issues early. Utilizing automated tools for static code analysis and dynamic application testing can uncover vulnerabilities that manual reviews might miss. Regular penetration testing is also essential to identify vulnerabilities that automated tools may not catch.

A secure development lifecycle is critical for maintaining security. This includes providing regular security training for developers and other stakeholders, appointing security champions within development teams, and including security checkpoints at different SDLC stages to ensure continuous security measures assessment.

Developing and maintaining a security incident response plan is also crucial for handling security incidents effectively. A well-defined incident response plan and regular drills ensure the team is prepared to respond promptly and effectively to security breaches.

Engaging in continuous improvement is also necessary. Conducting post-mortem analyses after security incidents helps understand what went wrong and what can be done to prevent similar future issues. Establishing a feedback loop allows for continuously improving security practices based on lessons learned and new threats.

Automate Vulnerability Scanning to Keep Your Application Secure 

Vulnerability scanning tools can detect insecure design issues in all the components necessary for application development. One of the best ways to keep design security in check is by conducting pre-code vulnerability scans on all infrastructure resources identified during the requirements gathering phase. 

This practice helps mitigate common weaknesses before integrating them into the software development lifecycle. Codacy Security can be your partner in every application security and design phase. We provide automated tools for static and dynamic application security testing, penetration testing, insecure dependency and secrets detection scanning, Infrastructure as Code (IaC) scans, and Supply Chain Security solutions. 

To see how we can help you keep your application secure, book a demo with one of our AppSec experts today or start your 14-day free trial today.