Is the MFA push notification approval deny method safe in O365 Concerns over phishing risks and user behavior

Question

Many organizations, including ours, are using the MFA push notification approval/deny method in Office 365 for user authentication. While it’s convenient, I’m concerned about the risk of phishing attacks where an attacker might trick users into approving a legitimate-looking push notification. How secure is this method? Are there better alternatives or steps to mitigate phishing risks while keeping user experience intact?

Answer 1

Multi-Factor Authentication (MFA) using push notifications in Office 365 enhances security by requiring users to approve or deny login attempts. However, this method is susceptible to MFA Fatigue attacks, where attackers bombard users with repeated authentication requests, hoping they will approve one inadvertently.

Security Concerns

• MFA Fatigue Attacks: Attackers exploit user fatigue by sending numerous push notifications, leading users to approve access out of frustration or confusion.

• Phishing Risks: Users may mistakenly approve malicious requests, especially if they are unaware of ongoing attack methods.

Mitigation Strategies

1. Enable Number Matching: Implement number matching in MFA, requiring users to enter a number displayed on the login screen into their authenticator app. This ensures the user is actively involved in the authentication process, reducing accidental approvals.

2. Implement Phishing-Resistant MFA: Consider adopting phishing-resistant MFA methods, such as FIDO2 security keys or certificate-based authentication, which provide stronger protection against phishing attacks.

3. User Education: Regularly train users to recognize and report unexpected MFA prompts and understand the importance of denying unsolicited authentication requests.

4. Monitor and Respond: Establish monitoring systems to detect unusual patterns of MFA requests and respond promptly to potential attacks.

Alternative MFA Methods

• Authenticator Apps with Number Matching: Enhances security by requiring user interaction beyond simple approvals.

• Hardware Security Tokens: Provide a physical layer of security, making unauthorized access more difficult.

• Biometric Authentication: Utilizes unique user characteristics, offering robust protection against unauthorized access.

While MFA push notifications offer convenience, they are vulnerable to specific attack vectors. Implementing number matching, educating users, and considering more secure MFA methods can significantly enhance your organization's defense against phishing risks and unauthorized access attempts.