CPAV is not a virus, but an antivirus program. If F-Secure
anti-virus products says that a program has been modified by Central
Point Antivirus, it means that CPAV has added a self-checking module
to the end of the program.
When a program modified in this way is executed, the added code
will first check that the length of the program is not changed,
and allows the program to execute only if this is not the case.
F-Secure anti-virus products will detect programs modified in this
way because the added code resembles virus code closely, and also
because several programs (including F-Secure anti-virus products)
will not run after a modification like this.