What type of malware might be introduced to the network when an employee downloads unverified software?

The scenario of an employee downloading unverified software can lead to the introduction of various types of malware, but in this context, a Trojan is the most relevant.

Trojan malware often masquerades as legitimate software but contains harmful code that can compromise the system once installed. Unlike viruses and worms, which can replicate and spread independently, Trojans rely on the user to execute their payload unwittingly. When unverified software is downloaded and installed, it is common for Trojans to be embedded within, allowing attackers access to sensitive information or control over the user's system.

While a virus attaches itself to legitimate files and replicates, and a worm self-replicates across networks, it’s the Trojan that specifically ties in with the scenario of an employee actively downloading software that appears innocuous but is, in fact, malicious. Adware, while it can be intrusive and undesirable, typically does not cause the severe consequences that Trojans can, as adware is focused on displaying advertisements rather than taking control of a system or stealing data. Thus, Trojans are a direct threat in cases of downloading unverified software.