Mobile apps and websites can be secured against common threats by integrating robust security practices throughout the entire development lifecycle. This proactive approach involves understanding prevalent risks, following secure coding standards, using strong authentication, encrypting data, and performing regular security testing.

Core security practices for both platforms

1. Use secure code practices

• Principle of least privilege: Grant only the minimum level of access necessary for a user or process to function. This limits potential damage if a part of the system is compromised.
• Data validation: All user input, regardless of its source, should be validated and sanitized on the server side to prevent injection attacks.
• Robust authentication and authorization: Enforce strong, complex passwords and multi-factor authentication (MFA). Implement proper session management with timeouts and use server-side verification for all access decisions.
• Data encryption: Encrypt sensitive data both "at rest" (in storage) and "in transit" (during communication) using strong, industry-standard algorithms like AES-256.
• Secure APIs: Secure all API connections with HTTPS/TLS, implement strong authentication, and use rate limiting to prevent abuse. 

2. Test and monitor continuously

• Regular security audits: Conduct routine code reviews and vulnerability assessments to fix bugs and address security weaknesses.
• Penetration testing: Simulate targeted cyberattacks to find and exploit vulnerabilities before attackers do. Testers can use black-box (no internal knowledge), white-box (full access), or gray-box (partial access) approaches.
• Automated security testing: Integrate tools like Static Application Security Testing (SAST) and Dynamic Application Security Testing (DAST) into your development pipeline to continuously scan for vulnerabilities.
• Monitor for suspicious activity: Use logging and monitoring tools to detect and respond to threats in real-time. 

3. Maintain your software and infrastructure

• Regular software updates: Keep all software, including content management systems (CMS), plugins, frameworks, and operating systems, up to date to patch known vulnerabilities.
• Website backups: Regularly back up your website data and store it in a secure, off-site location to ensure quick recovery after an attack.
• Web Application Firewall (WAF): Use a WAF to filter and block malicious traffic from reaching your website. 

4. Educate your team and users

• Train developers: Educate your development team on secure coding standards and the latest security threats to prevent vulnerabilities from being introduced.
• Train your users: Inform users about the importance of strong passwords, enabling MFA, and being cautious of phishing attempts.