Although it is considered a low tech attack ____________ is still a very effective way of gaining unauthorized access to network systems.

Sniffing is a technical attack involving the interception of network traffic, requiring specific tools and network access, which is not considered low-tech.

Eavesdropping is covertly listening to private communications, which can be a component of information gathering but is not the primary 'low-tech attack' for gaining network system access.

Social engineering is a low-tech attack that manipulates individuals into divulging confidential information or performing actions that compromise security, relying on deception rather than exploiting technical vulnerabilities.

Shoulder surfing is a physical attack where an attacker directly observes a user entering sensitive information, a specific technique rather than the broader category of psychological manipulation.