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-
-
- CASCADE SERIES
- ==============
-
- Version 1 (1701 bytes):
-
- The virus occurs attached to the end of a COM file. COM files
- increase in length by 1701 bytes. The first three bytes of the
- program are stored in the virus, and replaced by a branch to the
- beginning of the virus. The virus is encrypted (apart from the
- first 35 bytes) using an algorithm that includes the length of the
- host program, so every sample looks different. It becomes
- memory-resident when the first infected program is run, and it will
- then infect every COM file run (even if the file has an EXE
- extension). If the system date is between October and December 1988
- the cascade display will be activated at random intervals. The
- virus tests the BIOS for the string 'COPR. IBM', and will not infect
- if it finds this - however there are errors in the code which
- prevent it from working. Because recognition depends on the length
- of the virus, it will infect programs already infected by variants
- with different lengths.
-
-
- Version 2 (1704 bytes):
-
- COM files increase in length by 1704 bytes. The only differences
- from Version 1 are the removal of a conditional jump (which would
- never have been taken) and some necessary segment overrides on the
- BIOS tests missing in the previous version. There is still a
- mistake preventing an IBM machine from being recognised.
-
-
- Version 3 (1704 bytes):
-
- Same as Version 2 but has been modified, without recompiling, to
- format the hard disk. The formatting routine from Datacrime (1) has
- been written over the cascade display, and the activation routine
- changed to 1st October to 31st December, any year except 1993.
- Formatting will be after a random interval, maximum 5 minutes.
-
- ==== Computer Virus Catalog 1.2: Autumn Virus (July 15, 1989) ========
-
- Entry...............: Autumn (Leaves) Virus
- Alias(es)...........: Blackjack =1704- =Herbst(laub)= Cascade A-Virus
- Virus Strain........: Cascade- = Autumn- =Herbst-Virus
- Virus detected when.: September 1988
- where.: University of Konstanz, FRG
- Classification......: Program Virus (extending .COM), RAM resident
- Length of Virus.....: .COM filelength increases by 1704 byte
- -------------------- Preconditions -----------------------------------
-
- Operating System(s).: MS-DOS
- Version/Release.....: 2.xx upward
- Computer model(s)...: IBM-PC, XT, AT and compatibles
-
- -------------------- Attributes -------------------------------------
-
- Easy Identification.: ---
- Type of infection...: System: is infected if the call of interrupt 21h
- with function 4Bh and subfunction FFh is
- possible and without error and 55AAh is returned
- in DI- register.
-
- .COM file: Program virus, increases COM files by
- 1704 Byte. A .COM file is infected if the first
- instruction is a three byte jump with DISP16 =
- (filelength minus viruslength).
-
- .EXE file: no infection.
-
- Infection Trigger...: Infects all files that are loaded via the
- function 4Bh and subfunction 00h of the
- interrupt 21h (MS-DOS uses this function to
- start any program)
-
- Interrupts hooked...: Int21h, Int28h (only if Clockdevice Year =
- 1980), Int1Ch (only if damage is triggered)
-
- Damage..............: Transient Damage: Modifies screen by making the
- characters on the screen "fall down" on the
- screen in connection with clicking noises.
-
- Damage Trigger......: IF function GetDate returns with
- 1. ( year=1988 AND month>= 10 ) OR
- 2. ( year=1980 AND
- 2.1. clock is changed by user to year=1988
- month>=10 OR
- 2.2. clock is changed by user to year>1988 )
- AND a random number generator activates damage.
-
- Particularities.....: 1. If the system is _not_ infected, the
- invocation of an infected program produces
- errors (system crash is possible).
-
- 2. COM-files up to a length of 63800 bytes will
- be infected, but files with a length of more
- than 63576 bytes are not loadable after
- infection.
-
- 3. The virus-program is encoded, dependent of
- the .COM-filelength.
-
- 4. The distinction between .EXE and .COM files
- is made by testing the "magic number (MZ)" in
- the .EXE-Header.
-
- ------------------- Agents -----------------------------------------
-
- Countermeasures.....: Category 3: ANTIHBST.EXE (VTC Hamburg)
-
- Countermeasures successful: ANTIHBST.EXE is an antivirus that only
- looks for the HERBST-virus and, if
- requested, will restore the file.
-
- Standard means......: ---
-
- ------------------- Acknowledgement --------------------------------
-
- Location............: Virus Test Center, University Hamburg, FRG
- Classification by...: Michael Reinschmiedt
- Documentation by....: Michael Reinschmiedt
- Morton Swimmer
- Date................: July 15, 1989
-
-
- =================== End of Autumn-Virus ============================
-
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