A hacker initiated a social engineering attack and stole username and passwords of some users within a company. Which product should be used as a solution to this problem?

Cisco NGFW (Next-Generation Firewall) is a network security device that controls traffic based on rules and threat intelligence, not a solution for compromised user credentials.

Cisco AnyConnect is a VPN client for secure remote access, not a primary defense against stolen internal user credentials.

Cisco AMP for Endpoints focuses on advanced malware protection and detection on endpoints, not on preventing credential theft or unauthorized access via stolen credentials.

Cisco Duo provides multi-factor authentication (MFA), which adds an extra layer of security beyond just a username and password. Even if credentials are stolen via social engineering, attackers cannot access accounts without the second factor, significantly reducing the risk of unauthorized access.