A virus is generally considered to be an infection that runs code on the host (e.g., a Trojan horse). Viruses need an entry point and a host.

The entry points for a virus include:

The hosts for a virus are system-call interfaces that are accessible from the point of entry (an infected program), such as sendmail or an HTTP server. The hosts are platform-specific, so a virus for Linux would in all likelihood terminate the host under QNX Neutrino as soon as it tried to do anything damaging.

The viruses that circulate via email are OS-specific, generally targeted at Windows, and can't harm QNX Neutrino systems, since they simply aren't compatible. Most Unix-style systems aren't susceptible to viruses since the ability to do (much) damage is limited by the host. We have never heard of a true virus that could infect QNX Neutrino.

In addition, since deployed QNX Neutrino systems are highly customized to their designated application, they often don't contain the software that's open to such attacks (e.g., logins, web browsers, email, Telnet and FTP servers).