Security is a significant concern for .NET development companies, with challenges such as SQL injection, cross-site scripting (XSS), and unauthorized data access. Dot NET development company must implement strong authentication mechanisms, including OAuth, JWT, and multi-factor authentication (MFA). Secure coding practices like input validation, parameterized queries, and encrypting sensitive data help mitigate threats. Regular security audits, penetration testing, and compliance with industry standards such as GDPR and HIPAA are essential. Additionally, using Azure Security Center and firewall protections ensures robust security against cyber threats.