. https://www.alienvault.com/blogs/security-essentials/making-your-mfa-secure-tips-from-a-security-architect/
blog article
Many security breaches take place when attackers gain access to Internet-facing applications by using compromised credentials. As an added layer of security against leaked credentials, organizations have been implementing multi-factor authentication (MFA) mechanisms to verify the identity of users connecting to critical online assets. One of many multi-step authentication methods is phone call back. The authentication process starts with a user inputting a password that, once successfully validated, leads to a phone call on a registered device associated with the user’s account. After the user answers the phone and approves the login request, she is allowed to login. Unfortunately, phone callback verification is prone to misconfigurations resulting in compromises even in the presence of MFA. Things to watch out for in MFA. Ensure the option to enroll the next time users attempt to log is not available to connecting users. If available, attackers with a valid password can complete the enrollment on a user’s behalf using the phone number of their choice before the legitimate user ever accesses the system. It is critical that enrollment of legitimate users’ devices is completed prior to allowing access to applications protected by phone call back. Otherwise, the first step in the authentication process using a valid password should fail if a user has not completed the enrollment. READ MORE