SVC 5.0 Virus

 Virus Name:  SVC 5.0 
 Aliases:     USSR 3103, SVC V5.0 
 V Status:    Common 
 Discovered:  October, 1991 
 Isolated:    Israel 
 Symptoms:    .COM & .EXE growth; decrease in total system and available 
              memory; program corruption 
 Origin:      USSR 
 Eff Length:  3,103 Bytes 
 Type Code:   PRhAK - Parasitic Resident .COM & .EXE Infector 
 Detection Method:  ViruScan, Sweep, AVTK, NAV, F-Prot, IBMAV, PCScan, 
                    NAVDX, VAlert, ChAV, 
                    NShld, Sweep/N, LProt, Innoc, NProt, IBMAV/N, 
                    AVTK/N, NAV/N 
 Removal Instructions:  Delete infected files 
 General Comments: 
       The SVC 5.0, or USSR 3103, virus was isolated in Israel in 
       October, 1991.  It is believed to have originated within the 
       USSR.  USSR3103 is a memory resident infector of .COM and 
       .EXE programs, as well as overlay files.  It is a stealth virus. 
       The first time a program infected with SVC 5.0 is executed, the 
       virus will install itself memory resident at the top of system 
       memory but below the 640K DOS boundary.  Total system and 
       available free memory, as indicated by the DOS CHKDSK program, will 
       decrease by 3,120 bytes.  Interrupts 01, 03, 08, and 21 will be 
       hooked by the virus. 
       Once memory resident, SVC 5.0 will infect .COM and .EXE programs 
       as they are executed.  SVC 5.0 is a stealth virus, and when it 
       is memory resident, the infected program's file length increase 
       of 3,103 bytes will not be visible.  Likewise, attempts to view 
       programs infected with SVC 5.0 when the virus is memory resident 
       will result in a "clean" copy of the program being made available 
       in memory.  In reality, the programs increase in size by 3,103 
       bytes with the virus being located at the end of the file.  The 
       following text string can be found within the viral code: 
               "(c) 1990 by SVC, Vers. 5.0" 
       SVC 5.0 contains code which checks files when they are opened to 
       see if the file name is "AIDSTEST.C".  If the file being opened 
       has this name, then the virus will add a copyright message to 
       the file which reads: 
               "-* 1990-91 by SVC, Vers 6.0 *- 
       SVC 5.0 may also cause program corruption when multiple files are 
       open at the same time. 
       Known variant(s) of SVC 5.0 are: 
       SVC 5.0B: Functionally equivalent to the original SVC 5.0, this 
                 variant has some minor code changes. 
                 Origin:  USSR  February, 1992. 
       SVC 5.0C: Functionally equivalent to the original SVC 5.0, this 
                 variant has some minor code changes.  It contains the 
                 following text string: 
                 "(c) 1990 by SVC,Vers. 5.0" 
                 Origin:  USSR  October, 1992. 
       SVC 5.0D: Based on the SVC 5.0 virus, there are two major 
                 differences with this variant.  First, the virus hooks 
                 interrupts 13 and 21, instead of 01, 03, 08, and 21. 
                 Second, it doesn't contain the typical copyright notice 
                 found in the SVC 5.0 viruses. 
                 Origin:  USSR  October, 1992. 
       See:   SVC 3.1    SVC 4.0   SVC 6.0   SVC-2936   SVC.3241 

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