TL;DR
Users sharing passwords is a huge risk. This guide covers strategies to detect and prevent this, focusing on multi-factor authentication (MFA), session management, anomaly detection, user education, and account monitoring. It’s about making accounts harder to compromise even if credentials are leaked.
1. Implement Multi-Factor Authentication (MFA)
This is the single most effective step. Even if a password is shared, MFA adds another layer of security that makes it much harder for an attacker to gain access.
- Choose strong MFA methods: Avoid SMS-based MFA where possible (SIM swapping attacks are common). Prefer authenticator apps (Google Authenticator, Authy), hardware security keys (YubiKey), or platform authenticators (Windows Hello, Touch ID).
- Enforce MFA for all users: Don’t make it optional.
- Consider risk-based MFA: Prompt for MFA more often when a user logs in from an unusual location or device.
Example (using Google Authenticator):
# This is conceptual - implementation varies by system2. Robust Session Management
How your application handles user sessions impacts security.
- Session timeouts: Shorten session lifetimes to reduce the window of opportunity for a compromised account.
- Invalidate sessions on password change: Force users to re-authenticate after changing their password.
- IP address binding (with caution): Tie a session to a specific IP address. This can be disruptive if users travel, so use it carefully and allow for trusted IP ranges.
- User agent string tracking: Monitor changes in the user agent string during a session – a sudden change could indicate account takeover.
Example (session timeout configuration – conceptual):
# Session lifetime set to 30 minutes3. Anomaly Detection
Look for unusual activity that might indicate a shared account.
- Failed login attempts: Monitor for repeated failed logins, especially from different locations.
- Simultaneous logins: Detect when the same account is logged in from multiple locations at the same time. This is a strong indicator of compromise.
- Unusual access patterns: Track which resources users are accessing and flag any deviations from their normal behaviour.
- Geographic location monitoring: Alert on logins from unexpected countries or regions.
Example (detecting simultaneous logins – conceptual):
# Check for multiple active sessions per user4. User Education
Teach users about the risks of sharing their credentials.
- Regular security awareness training: Explain why password sharing is dangerous and the consequences it can have.
- Phishing simulations: Help users identify phishing attacks that attempt to steal their passwords.
- Password management tools: Encourage users to use strong, unique passwords generated by a reputable password manager.
5. Account Monitoring and Auditing
Regularly review account activity for suspicious behaviour.
- Audit logs: Enable detailed audit logging that records all login attempts, password changes, and access to sensitive resources.
- Automated alerts: Set up automated alerts to notify administrators of any suspicious activity.
- Regular reviews: Periodically review user accounts and permissions to ensure they are still appropriate.
Example (audit log entry – conceptual):
# Log entry showing a successful login from a new location6. Consider Passwordless Authentication
Where feasible, move away from passwords altogether.
- Biometric authentication: Use fingerprint or facial recognition.
- Magic links: Send a unique link to the user’s email address that allows them to log in without a password.
- Passkeys: A modern standard for secure, passwordless login using cryptographic keys stored on devices.