A VPN client is software that authenticates a user or device and builds an encrypted tunnel to a private network. It hides traffic from interception on untrusted networks and gives remote users access to internal resources as if they were on the local network.
In cyber security, VPN clients matter because they sit at a trust boundary: if the client, installer, or configuration is compromised, an attacker may gain a path into the environment or steal credentials and session data. Attackers may abuse this by distributing trojanized VPN clients, fake updates, or altered configuration files. Defenders reduce risk by installing clients only from trusted sources, verifying signatures, enforcing multifactor authentication, and monitoring remote-access logs for unusual connections.