OROPAX Virus

 


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==== Computer Virus Catalog 1.2: OROPAX-Virus (July 15, 1989) =======


Entry...............: OROPAX Virus

Alias(es)...........: Music Virus

Virus Strain........: ---

Virus detected when.: February 1989

Classification......: Program Virus (extending), Direct Action,

                      RAM-resident

Length of Virus.....: COM-files: length increased by 2756-2806 Byte,

                                 always divisable by 51.


-------------------- Preconditions ----------------------------------


Operating System(s).: MS-DOS

Version/Release.....: 2.xx upward

Computer model(s)...: IBM-PC, XT, AT and compatibles


-------------------- Attributes ------------------------------------


Easy Identification.: Typical texts in Virus body (readable with

                      HexDump facilities):  "????????COM" and

                      "COMMAND.COM"


Type of infection...: System: RAM-resident, infected if function 33E0h

                         of interrupt 21h returns 33E0h in

                         AX-register.  .COM File:  extending by using

                         FindFirst/FindNext- function in the home

                         directory until a COM File is encountered

                         with a different Attribute than N or A.

                         Files are only infected once.


                         The following .COM-files will not be

                         infected:


                         - COMMAND.COM,

                         - COM files with length divisible by 51,

                         - COM file with an attribute other than N or

                           A,

                         - COM files longer than 61980 Bytes.


                         .EXE File:  no infection.


Infection Trigger...: When any of the following INT 21h functions:

                         39h, 3Ah, 3Ch, 3D01h, 41h, 43h, 46h, 13h,

                         16h, or 17h are called; these functions are

                         also used by other resident DOS commands,

                         e.g.  MD, RD, DEL, REN, and COPY.


Interrupts hooked...: INT08h, INT20h, INT21h, INT27h


Damage..............: Transient Damage: After 5 minutes, the virus

                         will start to play three melodies repeatly

                         with a 7 minute interval in between.  This

                         can only be stopped with a reset.  OROPAX and

                         earcaps can be used to avoid "music

                         overload".


Damage Trigger......: Using a random number generator, the virus

                         decides whether to become active.


--------------------- Agents ---------------------------------------


Countermeasures.....: Category 3: ANTIORO.EXE (VTC Hamburg)


Countermeasures successful: ANTIORO.EXE finds and restores infected

                      programs (only for OROPAX).


Standard means......: notice .COM file length


-------------------- Acknowledgement --------------------------------


Location............: Virus Test Center, University Hamburg, FRG

Classification by...: Thomas Lippke

Documentation/Translation: Morton Swimmer

Date................: July 15, 1989


==================== End of OROPAX-Virus ===========================


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  ++++++++++++++++++++++++++ end of reports ++++++++++++++++++++++++

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