The Basics and Brief of Secure Software Development Lifecycle (SDLC) Checklist

Overview

Security in software development is often an afterthought, leaving applications vulnerable to attacks. This checklist provides essential, actionable security requirements to ensure secure coding practices are integrated throughout the software development lifecycle (SDLC). Designed for developers and teams, it helps mitigate common vulnerabilities, meet compliance standards, and build robust, secure applications.

What You’ll Learn

Security requirements gathering and analysis
Common attack patterns and vulnerabilities
Secure coding practices and guidelines
Password security and cryptographic implementations
Threat modeling and risk assessment
Security testing and monitoring strategies

Prerequisites

Basic understanding of software development
Familiarity with web application architecture
Understanding of common programming languages
Basic knowledge of cybersecurity concepts

Security in Software

Gather Software Requirements

In the software development process, gathering requirements is crucial for aligning security and functionality. Key types of requirements include:

Security Requirements: Ensure the software addresses compliance and protection needs, such as user access control, data protection, and role-based access.

User Requirements: Define what users should be able to do, like login methods and feature access.

Business Requirements: Identify the specific needs the software must meet for the organization.

Compliance Requirements: Consider legal and industry standards (e.g., HIPAA, PCI-DSS).

Platform Requirements: Specify deployment environments, whether on-premises or cloud-based.

Factors that Undermine Software Security

Security can be compromised by three key factors:

Product: Software vulnerabilities and poor configurations can expose the system to attacks.
People: Users and developers can unintentionally create security risks through errors or assumptions.
Process: Without proper security reviews and testing, flaws can go unnoticed.

Software Vulnerabilities & Attack Phase

Software vulnerabilities expose systems to attacks. Attackers often follow these phases:

Survey and Assess: Attackers identify weaknesses by observing software behavior, looking for exploitable flaws (e.g., no SSL, input fields vulnerable to cross-site scripting).
Exploit and Penetrate: Once vulnerabilities are found, attackers exploit them to gain access (e.g., using buffer overflows or privilege escalation techniques).
Maintain Access: Attackers secure long-term access by creating accounts or using backdoors.
Deny Service: If attackers cannot exploit the system further, they may disrupt it by overloading resources (e.g., denial-of-service attacks).

Attack Patterns

Attackers often follow recognizable patterns to exploit software vulnerabilities:

Reconnaissance: Gathering information, such as version numbers or system configurations, to identify weaknesses.
Brute Force: Automated attempts to guess login credentials by trying numerous combinations.
Authentication Abuse: Exploiting weak authentication mechanisms or bypassing login processes.
Input Manipulation: Injecting harmful data into forms or inputs, such as cross-site scripting (XSS) or command injection.
Denial of Service (DoS): Overloading a system to make it unavailable to legitimate users.

Password Security

New Password Requirements

To strengthen password security, implement policies that disallow sequences of three or more repeating characters (e.g., “111” or “aaa”). Developers must modify their password validation functions to ensure:

Minimum requirements: At least 8 characters, including uppercase, lowercase, a number, and a special character.
No repetition: Passwords should not contain sequences of three or more identical characters.

Hashing Passwords

Storing passwords securely requires hashing, not plain text storage. To improve security:

Use a Salt: Add a unique, cryptographically secure salt to each password before hashing to prevent attacks using precomputed tables (rainbow tables).
Select Strong Algorithms: Avoid outdated algorithms like MD5. Use more secure options like PBKDF2 with SHA-512, bcrypt, or scrypt.
Increase Iterations: Implement key derivation functions with many iterations (e.g., 100,000 or more) to slow down brute force attacks.

Vulnerability Management

Vulnerabilities Intelligence

Keeping up with software vulnerabilities is essential for preventing exploits:

Vulnerability Databases: Regularly check sources like Exploit DB, OWASP, and MITRE for updates on known vulnerabilities.
Automated Alerts: Subscribe to services (e.g., Microsoft Security Bulletins, GitHub notifications) to receive real-time updates on security patches and risks.
Monitor Dependencies: Track vulnerabilities in your software’s dependencies and third-party libraries to ensure no inherited risks.
Active Research: Regularly search issue trackers (e.g., Node.js, Python) for bugs that could introduce security risks.

Handling Vulnerabilities

Bugs in Software

Bugs are inevitable in software and can lead to significant security vulnerabilities:

Bug Lifecycle: Bugs are discovered, reported, and fixed, but may introduce new bugs in the process.
Types of Errors: Error, Fault, Defect, Failure
Security Risks: Bugs like buffer overflows can lead to serious exploits, such as remote code execution.
Preventative Measures: Proactively design with security in mind, conduct thorough testing, and use standardized coding practices.

External Libraries and Software

Using external libraries and third-party services can save development time but introduces risks:

Dependencies: Libraries and cloud services may have vulnerabilities. Always vet them thoroughly.
Trust Issues: Don’t assume standard libraries are free of security flaws.
Encryption: Never create your own encryption—always rely on trusted, vetted algorithms.
Cloud Service Security: Use proper configurations and secure data transmissions.

Secure Design Principles

Principles of Secure Design

Secure design should be integrated from the beginning:

Minimize Attack Surface: Only include necessary features to reduce points of vulnerability.
Secure Defaults: Systems should be secure by default, without requiring extra configuration.
Least Privilege: Limit user and system permissions to only what is necessary.
Fail Securely: In case of failure, systems should default to a secure state, denying access.
Don’t Trust External Services: Always validate and sanitize data coming from external services.
Keep It Simple: Simple designs are easier to secure, maintain, and audit.

Common Security Design Flaws

Avoid these common security design flaws:

Hardcoded Credentials: Storing sensitive information like passwords or API keys directly in the code
SQL Injection: Failing to properly sanitize user inputs
Weak Cryptography: Using outdated algorithms like MD5 for hashing
Excessive Trust: Assuming user inputs or external services are safe without validation
Rigid Authorization: Hardcoding roles and user IDs in the system

Risk Management

Understanding Risk and Threats

Managing risk involves identifying potential threats and vulnerabilities:

Threats: Malicious attackers, natural disasters, or unintended user actions
Vulnerabilities: Weak points in the system that could be exploited
Consequences (Impact): The impact of a successful attack

Risk Formula:

Risk = Threat × Vulnerability × Impact

Threat Modeling

Define Security Objectives: Establish guidelines and compliance requirements
Decompose the System: Break down the application into components
Identify Threats: Consider potential attacks and rank them by severity
Countermeasures: Implement best practices to mitigate risks

Risk Response Strategies

Risk Avoidance: The most secure code is code that isn’t written
Risk Transfer: Outsource risk to external services better equipped to handle specific threats
Risk Mitigation: Identify vulnerabilities and take steps to minimize likelihood or impact
Risk Acceptance: Accept low-impact risks based on cost-benefit analysis

Secure Coding Guidelines

General Guidelines

Input Validation: Always validate and sanitize user inputs
Avoid Deprecated Functions: Use updated libraries and functions
Memory Management: Ensure proper handling of memory
Principle of Least Privilege: Limit user access to necessary functions and data
Error Handling: Implement proper exception handling
Secure Configurations: Use HTTPS, secure tokens, and strong encryption
Check External Dependencies: Regularly review and update third-party libraries

Buffer Overflows and Prevention

Buffer overflows occur when data exceeds a buffer’s capacity:

Prevention:

Use safe functions like strncpy
Validate inputs to ensure data stays within limits
Perform bounds checking on memory buffers
Use higher-level languages like Python or Rust

Race Conditions

Race conditions occur when multiple processes access shared resources simultaneously:

Prevention:

Use locks to control access to shared resources
Employ atomic operations
Use asynchronous programming patterns

Platform-Specific Vulnerabilities

Web Application Vulnerabilities

Weak Authentication and Session Management
Injection Attacks
Cross-Site Scripting (XSS)
Insecure Access Control
Misconfigurations

Mobile Application Vulnerabilities

Misuse of Device Permissions
Insecure Data Storage
Unencrypted Communication
Weak Authentication

IoT Vulnerabilities

Insecure Web Interfaces
Unencrypted Data Transmission
Lack of Updates
Physical Security

Desktop Vulnerabilities

DLL Injection
Shell Code Injection
Debugging Ports

Implementation Protections

Secure Session Management

Store session IDs in cookies, not URLs
Use “secure” and “HTTP-only” flags
Implement session timeouts

Users, Protections, and Passwords

Use third-party authentication services
Enforce strong password policies
Enable two-factor authentication
Implement secure password recovery

Encryption and Data Protection

Symmetric Encryption: Same key for encryption and decryption
Asymmetric Encryption: Public key for encryption, private key for decryption
Hashing: One-way process for password storage
Salting: Add random data to hashes

Best Practices:

Use strong algorithms like AES or RSA
Avoid outdated algorithms like MD5 or SHA-1
Encrypt data in transit and at rest
Safeguard keys and avoid hardcoding credentials

Testing and Monitoring

Testing Software for Security

Penetrate and Patch: Find and fix security flaws quickly
Penetrate and Improve: Use findings to strengthen overall security
Build Security In: Review code, policies, and architecture
Static and Dynamic Testing: Check code before and during runtime
Code Reviews: Regular code review and unit testing

Monitoring and Logging

Active & Passive Monitoring: Real-time alerts and pattern analysis
Comprehensive Logging: Log key events from critical systems
Alert on Anomalies: Set alerts for unusual behavior
Coordinate with Security: Ensure logs are securely stored and reviewed

Conclusion

This SDLC security checklist provides a comprehensive framework for integrating security throughout the software development lifecycle. By following these guidelines and implementing the recommended practices, development teams can significantly reduce security risks and build more robust, secure applications.

Remember that security is not a one-time effort but an ongoing process that requires continuous attention, monitoring, and improvement as new threats and vulnerabilities emerge.

References

CERT Secure Coding Standards. Top 10 Secure Coding Practices. Software Engineering Institute, Carnegie Mellon University
CertNexus. (2023). Cyber Secure Coder Exam CSC-210 Blueprint. CertNexus.
National Institute of Standards and Technology. Security and Privacy Controls for Information Systems and Organizations. NIST Special Publication 800-53, Revision 5, 2020
National Institute of Standards and Technology. Security Considerations in the System Development Life Cycle. NIST Special Publication 800-64, Revision 2, 2008
The OWASP Foundation. OWASP Top Ten. 2021
Stallings, William. Cryptography and Network Security: Principles and Practice. 8th ed., Pearson, 2020.
Whitman, Michael E., and Herbert J. Mattord. Principles of Incident Response & Disaster Recovery. 3rd ed., Cengage Learning, 2021.
MITRE. “Software Configuration.” MITRE ATT&CK®

Next Steps

Implement secure coding practices in your current projects
Conduct security assessments using the provided checklist
Stay updated with the latest security vulnerabilities and patches
Consider additional security training and certifications