Viruses that are detected by AVP engine as 'Virus.Sim' are so-called 'safe' viruses. They are generated by the Rosenthal Virus Simulator. Here's how the author of this Virus Simulator describes these viruses:
"These Virus Simulator programs generate safe and sterile, controlled test suites of sample virus programs. Virus Simulator's ability to harmlessly compile and infect with safe viruses, is valuable for demonstrating and evaluating anti-virus security measures without harm or contamination of the system. The infected programs can be used as bait for virus detecting programs to gain practical virus protection experience."
These viruses do not possess any threat as they don't replicate. They can be only used for anti-virus products testing.
Disinfection & Removal
Description Created: Mikko Hypponen, F-Secure