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Secure Coding Best Practices

Anjul Sahu

Anjul Sahu


Every single day, an extensive array of fresh software vulnerabilities is unearthed by diligent security researchers and analysts. A considerable portion of these vulnerabilities emerges due to the absence of secure coding practices. Exploiting such vulnerabilities can have severe consequences, as they possess the potential to severely impair the financial or physical assets of a business, erode trust, or disrupt critical services.

For organisations reliant on their software for their operations, it becomes imperative for software developers to embrace secure coding practices. Secure coding entails a collection of practices that software developers adopt to fortify their code against cyberattacks and vulnerabilities. By adhering to coding standards that embody best practices, developers can incorporate safeguards that minimise the risks posed by vulnerabilities in their code.

In a world brimming with cyber threats, secure coding cannot be viewed as optional if a business intends to maintain its shield of protection.

This article, we will explore some anti-patterns and best practices we can include in our workflow.

Anti-patterns

Now, let's briefly discuss various common mistakes or anti-patterns, categorised into insecure coding. The following are some examples:

  • Insufficient validation of input data or processing inputs without proper encoding or sanitisation.
  • Constructing SQL queries by concatenating strings, making the code vulnerable to data leaks or injection attacks.
  • Failure to implement robust authentication, such as storing credentials in plain text without proper hashing and encryption.
  • Poor design of password recovery mechanisms and infrequent rotation of security keys.
  • Software planning and design lacking strong authorisation schemes.
  • Granting excessive privileges during development or troubleshooting.
  • Exposing sensitive information in debug logging without appropriate redaction.
  • Utilising third-party libraries from untrusted sources or neglecting security checks.
  • Unsafe handling of memory pointers or allowing pointer access beyond system boundaries.

With these common mistakes in mind, let's explore practices and tools that can guide developers towards secure coding practices.

Secure Coding Best Practices

Shift left in software development lifecycle

Historically, the conventional practice involved assigning the software security team to conduct security testing towards the conclusion of a software development project. The team would assess the application and compile a list of issues that require resolution. At this stage, the identified fixes would be prioritised, resulting in some vulnerabilities being addressed while others remained unattended. The reasons for leaving certain vulnerabilities unresolved could range from cost constraints and limited resources to pressing business priorities.

However, this traditional approach is no longer sustainable. Security considerations must now be incorporated right from the outset—the initial stages—of the software development lifecycle. Security should be taken into account during the design phase itself. Both manual and automated testing should be conducted throughout the application's implementation as part of the Continuous Integration (CI) pipeline, ensuring that developers receive prompt feedback.

To aid in this endeavour, the utilisation of static code analysis becomes invaluable. This technique enables the scanning of code for security flaws and risks, even while developers are actively writing it within an integrated development environment (IDE). For instance, SAST tools offers the ability to analyse the code for security vulnerabilities during the development process, facilitating early identification and mitigation of potential risks.

Input validation

Ensuring the integrity of input data as it enters a system holds great significance. It is essential to validate the syntactic and semantic accuracy of all incoming data, considering it as untrusted. Employing checks and regular expressions aids in verifying the correctness, size, and syntax of the input.

Performing these validations on the server side is highly recommended. In the case of web applications, it involves scrutinising various components, including HTTP headers, cookies, GET and POST parameters, as well as file uploads.

Client-side validation also proves beneficial, contributing to an enhanced user experience by reducing the need for multiple network requests resulting from invalid inputs. This approach minimises back-and-forth communication and enhances efficiency.

Parameterised queries

During the process of storing and retrieving data, developers frequently engage with datastores. However, if they overlook the utilisation of parametrised queries, it can expose an opportunity for attackers to exploit widely accessible tools and manipulate inputs to extract sensitive information. SQL injection, a highly perilous application risk, exemplifies a common form of such attacks.

By incorporating placeholders for parameters within the query, the specified parameters are treated as data rather than being considered as part of the SQL command itself. To mitigate these vulnerabilities, it is recommended to employ prepared statements or object-relational mapping (ORM) techniques. These approaches offer effective measures to safeguard against SQL injection and related threats.

Encoding data

Encoding data plays a vital role in mitigating threats by transforming potentially hazardous special characters into a sanitised format. Base64 encoding serves as an exemplar of such encoding techniques, offering protection against SQL injection, cross-site scripting (XSS), and client-side injection attacks.

To enhance security, it is crucial to specify appropriate character sets, such as UTF-8, and encode data into a standardised character set before further processing. Additionally, employing canonicalisation techniques proves beneficial. For instance, simplifying characters to their basic form helps address issues such as double encoding and obfuscation attacks, thereby bolstering overall security measures.

Implement identity and authentication controls

To further enhance security and minimise the risk of breaches, secure coding practices emphasise the importance of verifying a user's identity at the outset and integrating robust authentication controls into the application's code.

Here are some recommended measures to achieve this:

  • Employ strong authentication methods, such as multi-factor authentication, to add an additional layer of security.
  • Consider incorporating biometric authentication methods, such as fingerprint or facial recognition, especially in mobile applications.
  • Ensure secure storage of passwords. Typically, this involves hashing the password using a strong hashing function and securely storing the encrypted hash in a database.
  • Implement a secure password recovery mechanism to facilitate password resets while maintaining security.
  • Enable session timeouts and inactivity periods to automatically terminate idle sessions.
  • For sensitive operations like modifying account information, enforce re-authentication to validate the user's identity.
  • Conduct regular audits of authentication transactions to detect any suspicious activities and maintain a vigilant stance against potential threats.

Implement access controls

Incorporating a well-thought-out authorisation strategy during the initial stages of application development can greatly enhance the overall security posture. Authorisation entails determining the specific resources that an authenticated user can or cannot access.

Consider the following guidelines to strengthen the authorisation framework:

  • Establish a sequential flow of authentication followed by authorisation. Implement a mechanism where all requests undergo access control checks.
  • Adhere to the principle of least privilege, initially denying access to any resource that has not been explicitly configured for access control.
  • Enforce time-based limitations on user or system component actions by implementing expiration times, thereby ensuring that actions have defined timeframes for execution.

By following these practices, developers can create a robust and effective authorisation system that bolsters the overall security of the application.

Protect sensitive data

In order to comply with legal and regulatory obligations, it is the responsibility of businesses to safeguard customer data. This sensitive data encompasses various categories, including:

  • Personally identifiable information (PII)
  • Financial transactions
  • Health records
  • Web browser data
  • Mobile data etc

To prevent data leakage, it is crucial to employ robust encryption methods for both data at rest and data in transit. Consider the following practices to enhance data protection:

  • Utilise a well-established, peer-reviewed cryptographic library and functions that have been vetted and approved by your security team.
  • Avoid storing encryption keys alongside the encrypted data to prevent unauthorised access.
  • Refrain from storing confidential or sensitive data in memory, temporary locations, or log files during processing.
  • Implement redaction technique in log forwarders to remove sensitive information.
  • Implement mandatory re-authentication when accessing sensitive data within the application.

Implement logging and intrusion detection

Even the most meticulously designed system can be susceptible to exploitation by attackers. Therefore, it is advisable to incorporate a monitoring system that can detect and identify unusual events. It is crucial to ensure that sufficient information is logged concerning authentication, authorisation, and resource access events. This logging should include details such as timestamps, the origin of access requests, IP addresses, and information pertaining to the requested resource. It is important to store this information in a secure and protected log. Typically, these logs are transmitted in real time to a centralised system where they are analysed for any anomalies. Prior to logging, apply encoding techniques to the untrusted data to safeguard against log injection attacks.

In the event of a security breach, it is essential to have a well-documented playbook in place to promptly terminate system access, mitigating the risk of further data leakage. By following these practices, organisations can enhance their ability to detect and respond to potential intrusions, minimising the impact of security incidents.

Leverage security frameworks and libraries

Avoid unnecessary duplication of effort. Instead, leverage established security frameworks and libraries that have been proven effective. When incorporating such components into your project, ensure they are sourced from reliable and trusted third-party repositories. It is important to regularly assess these libraries for any vulnerabilities or weaknesses and proactively keep them up to date.

By adopting this approach, you can benefit from the expertise and experience embedded in these established security solutions, saving valuable time and effort while maintaining a strong security posture.

Monitor error and exception handling

In line with the best practices of logging, it is advisable to adopt a centralised approach for handling and monitoring errors and exceptions with tools like Sentry. Effective management of errors and exceptions is crucial as mishandling them can inadvertently expose valuable information to potential attackers, enabling them to gain insights into your application and platform design.

Consider the following measures to strengthen error and exception handling:

  • Avoid logging sensitive information within error messages to prevent inadvertent disclosure.
  • Regularly conduct code reviews to identify and address any weaknesses or vulnerabilities in the error handling implementation.
  • Utilise negative testing techniques, such as exploratory and penetration testing, fuzzing, and fault injection, to actively identify and rectify potential issues related to error handling.

By implementing these practices, you can ensure that error and exception handling is performed securely and with minimal risk of exposing sensitive information to potential attackers.

Benefits of implementing secure coding practices

At this point, the advantages of embracing secure coding practices should be evident:

  • Incorporating automated checks and code analysis during the development process enhances developer productivity by promptly providing feedback to improve code security. This leads to quicker time-to-market and higher-quality code.
  • Cost optimisation within the software development lifecycle is achieved by minimising bugs at the early stages.
  • Static application security testing (SAST) tools offer developers of all skill levels guardrails, AppSec governance, and valuable insights through IDE plugins. These tools equip developers with the necessary knowledge and resources to bolster application security.

Conclusion

Throughout our examination of coding flaws that can result in vulnerabilities, we have also explored best practices to enhance the security stance of software. However, in the context of large-scale projects, it can be daunting to implement these practices while ensuring proper governance.

In the realm of extensive projects, the following considerations can help navigate these challenges effectively:

  • Establish clear governance frameworks that outline security requirements, procedures, and responsibilities.
  • Develop comprehensive guidelines and standards that align with secure coding practices and provide actionable steps for implementation.
  • Foster collaboration and communication among development teams, security experts, and stakeholders to ensure a shared understanding of security goals and the necessary measures to achieve them.
  • Prioritise the implementation of security measures by identifying high-risk areas and focusing resources accordingly.
  • Regularly assess and review the security posture of the software throughout the development lifecycle, enabling continuous improvement and adjustments as needed.

By adopting these approaches, the process of implementing secure coding practices within large projects becomes more manageable and ensures that proper governance is in place to safeguard against vulnerabilities effectively.

It is advisable to create and automate workflows using SAST tools and integrate in CI to enforce the best practices. Feel free to schedule a non-obligatory call with us to discuss DevSecOps strategy and we can help you improve your current practice.

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