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-
- ICELANDIC SERIES
- ================
-
- There are four versions of the Icelandic virus.
-
- All infect EXE files only and they are easily distinguised by their
- file lengths:
-
- 632 One in two programs loaded are infected and one
- cluster is marked as bad on Hard Disks larger than
- 20 MB
-
- 642 Minor variant
-
- 656 One in ten programs loaded are infected
-
- 848 Displays message: "Gledileg jol" (Merry Christmas)
- if an infected program is run on 24th December.
-
-
- ==== Computer Virus Catalog 1.2: Icelandic#2 Virus (Sept. 20, 1989)=
-
- Entry...............: "Icelandic virus" (Version #2)
- Alias(es)...........:
- Virus Strain........: Icelandic Virus
- Virus detected when.: July 20 1989
- where.: Iceland
- Classification......: .EXE file infecting virus/Extending/Resident
- Length of Virus.....: 1. 632-647 bytes added to file
- 2. 2048 bytes in RAM
- -------------------- Preconditions --------------------------------
-
- Operating System(s).: MS-DOS
- Version/Release.....: 2.0 or higher
- Computer model(s)...: IBM PC,XT,AT and compatibles
-
- ------------------- Attributes ------------------------------------
-
- Easy Identification.: .EXE Files: Infected files end in 18 44 19 5F
- (hex). System: Byte at 0:37F contains FF (hex)
-
- Type of infection...: Extends .EXE files. Adds 632-647 bytes to the
- end of the file. Stays resident in RAM, hooks
- INT 21 and infects other programs when they are
- executed via function 4B. It will remove the
- Read-Only attribute if necessary, but it is not
- restored. .COM files are not infected.
-
- Infection Trigger...: Every tenth program run is checked. If it is an
- uninfected .EXE file it will be infected.
-
- Storage media affected: ---
- Interrupts hooked...: INT 21
- Damage..............: none
- Damage Trigger......:
-
- Particularities.....: The virus modifies the MCBs in order to hide
- from detection. The INT 13 checking in the
- Icelandic-1 has been removed. The virus uses
- the name of the file to determine if it is an
- .EXE file, but not the true type, as determined
- by the first 2 bytes. The virus assumes the
- program reserves all available memory (FFFF
- paragraphs needed). Programs that donot will
- cause a system crash when infected and run.
- This virus is a version of the Icelandic-1
- virus, modified so that it does not use INT 21
- calls to DOS services. This is done to bypass
- monitoring programs.
-
- Similarities........:
- ------------------- Agents ----------------------------------------
-
- Countermeasures.....: All programs which check for .EXE file length
- changes will detect infections.
- Countermeasures successful:
- Detection of infection:
- F-FCHK (from F.Skulason's F-PROT package)
- VIRUSCAN
- Prevention of infection: F-FCHK
- Removal: F-FCHK
- Standard means......: Use DEBUG to check the byte at 0:37F.
-
- -------------------- Acknowledgement -------------------------------
-
- Location............: University of Iceland/Computing Services
- Classification by...: Fridrik Skulason (frisk@rhi.hi.is)
- Documentation by....: Fridrik Skulason
- Date................: Sept 20, 1989
- Information Source..:
-
- ==================== End of Icelandic#2-Virus ======================
-
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