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- *** PC-Virus Index ***
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- YANKEE DOODLE SERIES, aka TP, VACSINA.
- ======================================
-
- There is said to be 50 versions in this series of viruses, which
- were written in Bulgaria by 'TP' during the period December 1988 to
- Summer 1990, although only 15 versions have been seen and only two
- seem to have propagated widely.
-
- All the viruses have been carefully written to avoid causing damage
- as far as possible. TP's development cycle was to write a virus and
- then to produce an antidote for it, which he called 'Vacsina' (the
- Bulgarian name for 'vaccine'. The 'VACSINA' string appeared in some
- of the early viruses, hence the name.
-
- Version 5 (Catalog entry follows) was the first version reported in
- the West in August 1989. This version 'beeped' when it it succeeded
- in infecting a file, a feature that was removed in Version 18.
-
- The viruses are version numbered and an earlier version will not
- infect a machine infected by a newer one. Some later versions play
- the tune "Yankee Doodle".
-
- An earlier but different Bulgarian virus also plays the same tune
- and this is known as YANKEE-2 (qv).
-
- The last version, Version 50, is said to use 80286 protected mode
- instructions to circumvent interrupt monitoring software when
- running on 286 machines (or later), although this has not been
- confirmed.
-
-
- ==== Computer virus catalog: VACSINA Rev. 2 (Nov. 14, 1989) ========
-
- Entry.................. VACSINA virus
- Alias(es).............. ---
- Strain................. ---
- Detected: when......... Early August 1989
- where........ University of Cologne, West-Germany
- Classification......... Filevirus/resident with update facility
- Length of virus........ length added to a COM-type file 1206-1221
- bytes
- length added to a EXE-type file 132 bytes and
- then like a COM-type file
-
- -------------------- Preconditions-----------------------------------
-
- Operating System(s).... MS-DOS
- Version/Release........ ---
- Computer models........ IBM-PC, XT, AT, PS/2 and compatibles
-
- -------------------- Attributes--------------------------------------
-
- Easy identification.... The string 'VACSINA' in the viruscode
- the last 4 bytes of an infected file show
- F4 7A 05 00
- memorysegment 0000:00C5 contains 7F 39 05
- when VACSINA is resident.
- The bytes 05 00 at the end of the file and
- the 05 in memory 0000:00C7 are version-
- numbers of VACSINA (see below).
-
- Type of infection...... VACSINA installs a TSR that trapps INT 21H
- function 4BH (load & execute). Every file
- that is loaded via this function will be
- infected (provided some constraints are met
- see below)
- VACSINA checks the version number (current is
- 0005) and will remove earlier versions of
- itself and substitute with the newer virus
- code!
-
- Infection trigger...... Executing an uninfected file after an infected
- file was used.
-
- Media affected......... Any via INT 21H funtion 4BH loadable file,
- that either starts with E9H (jump) or 'MZ'
- (EXE header). This includes COM, EXE, OVL, and
- APP (GEM) files.
- Files with the leading E9 must be bigger
- than 1206 and smaller than 62867
- Files with a EXE-Header must not be bigger
- than 64947 for the 132 loader attachment.
- after that they have to meet the constraints
- of a E9H headed file.
-
- Interrupts hooked...... INT 21H (function 4BH), INT 24H
- The INT 31 table entry is used as the VACSINA
- present flag.
-
- Damage................. After a successfull infection of a COM-type
- file a beep (DOS-BELL) is issued.
-
- NO OTHER PAYLOAD !
- This looks like test code for the infection-
- mechanism.
-
- Damage trigger......... The beep is triggered when a COM-Type file is
- successfully infected.
-
- Particularities........ Probably a test version that prematurely
- escaped since there is no payload, the beep
- when infecting another file, and some
- incomplete codesections. The virus opens a
- file 'VACSINA' and closes it after a while,
- never writing or reading from it. The
- returncodes of the open and close operations
- are ignored. The words for vaccine are
- written with two Cs in all languages that use
- latin letters except for norvegian (they write
- vaksine). The virus has an update facility
- and will replac old versions with new versions
- of itself!
-
- Similarities........... ---
-
- --------------------- Agents---------------------------------------
-
- Countermeasures........ ANTI-VD of the MVC (University of Karlsruhe)
- detects and removes the virus from any file.
- EXE-headers are reconstructed!
-
- Countermeasures successful ---
- Standard Means......... The DEL command after booting from a clean
- systemdisk.
-
- ------------------- Acknowledgements -------------------------------
-
- Location............... Micro-BIT Virus Center University of Karlsruhe
- West-Germany
- Classification by...... C. Fischer, T. Boerstler, R. Stober
- Documentation by....... C. Fischer, T. Boerstler, R. Stober
- Date................... Nov. 13, 1989
- Information source..... The update feature was first discovered by
- David M. Chess, Yorktown Heights
-
-
- ============== END OF VACSINA VIRUS =================================
-
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- ++++++++++++++++++++++++++ end of reports ++++++++++++++++++++++++
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