Flash Virus

 Virus Name:  Flash 
 V Status:    Rare 
 Discovered:  July 1990 
 Symptoms:    .COM & .EXE growth; decrease in available free memory; video 
              screen flicker 
 Origin:      West Germany 
 Eff Length:  688  Bytes 
 Type Code:   PRfA - Parasitic Resident .COM & .EXE Infector 
 Detection Method:  ViruScan, NAV, AVTK, F-Prot, Sweep, IBMAV, 
                    NAVDX, VAlert, PCScan, ChAV, 
                    NShld, LProt, Sweep/N, Innoc, NProt, AVTK/N, 
                    NAV/N, IBMAV/N 
 Removal Instructions:  NAV, or delete infected files 
 General Comments: 
       The Flash virus was discovered in July 1990 in West Germany.  Flash 
       is a memory resident generic file infector, and will infect .COM and 
       .EXE files, but not COMMAND.COM. 
       The first time a program infected with the Flash virus is executed, 
       the virus will install itself memory resident.  976 bytes will be 
       allocated in high memory, and available free memory will decrease by 
       a corresponding 976 bytes.  A mapping of memory will also indicate 
       that when Flash is resident in memory, interrupts 00, 23, 24, 30, 
       ED, F5, and FB are now in free memory.  Total system memory reported 
       by DOS, as well as low memory used by the operating system and TSRs 
       will not have changed. 
       Once Flash is memory resident, each time a .COM or .EXE program is 
       executed it is a candidate for infection.  An uninfected .EXE 
       program will always be infected upon execution.  Uninfected .COM 
       files are only infected if they are greater than approximately 500 
       bytes in length.  Infected files will always increase in length by 
       688 bytes. 
       After June of 1990, systems with a graphics capable monitor may 
       notice a screen flicker occurring at approximately seven minute 
       intervals. The virus causes this effect by manipulating some screen 
       blanking bits every seven minutes. 

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