What is a foreign computer program that often enters a system through email attachments?

A virus is indeed a type of foreign computer program that typically enters a system through email attachments. This type of malicious software is designed to replicate itself and infect other files or systems, often without the user's knowledge. Viruses can cause a range of issues, from minor annoyances, such as slowing down a system, to more serious problems like data corruption or loss.

In many cases, a virus masquerades as a harmless file or program that encourages users to open it, such as a document or image sent via email. Once opened, the virus can execute its payload, leading to the aforementioned consequences. This characteristic of spreading through file attachments distinguishes it from other types of malicious software, such as spyware or malware in general, which may have different vectors of infection and objectives.

Spyware, for example, is designed specifically to gather information about a user without their knowledge, while malware is a broader term encompassing various malicious software types, including viruses and spyware. A browser hijacker, on the other hand, redirects a user's web browser to specific webpages, often as part of adware practices, and does not typically enter a system through email attachments.