LZ_Link

Alias:-
Strain:
detected when:
where:
Classification:Not reset-resident Link-Virus (ext. Hunk-length)
Length:1.Length (400) on storage medium 2.Length (400) in RAM

Preconditions

Operating System(s):AMIGA-DOS
Version/Release:DOS-V33/34, KICK 1.2 / 1.3
Computer model(s):A500,A1000,A2000,A2500
Caroname:LZ_Link

Attributes

Easy identification:none-

Type of Infection:

Self-Identification methods on Disk: None (multiple links possible) Self-Identification methods in Memory: Checks Globalvec Write for ROM-call Executable File infection: Extending Hunk-Length, only able to infect files with two Hunks correctly. Searches for RTS (Return from Sobroutine) command and substitutes this with a branch to the Virus-entry point. (hiding Virus-entry point.) not Reset-resident, RAM-Resident, hooks Globalvec 06=Write of DOS-Base Infects on File-Modification like copy (slow-Infector) Infection-Preconditions: - No residents/overlays to load - File executeable ($3e9 found) - CODE-HUNK length > 1000 Bytes - First Codehunk does not contain JMP-cmds in the last 51 Words (beeing a Library for Ex.)

Infection Technique:
Infection Trigger:- Writing Executeable file (Copy, Compile)
Storage Media affected:All media
Interrupts hooked:DOS-GLOBALVEC 06 WRITE (Internal vec.)
Stealth:
Tunneling/Selfprot:
Oligo/Polymorphism:
Encoding Method:
Damage:Permanent Damage: none Transient Damage: none Transient/Permanent damage: Some infected files will not run due to a bug in the infection routine. Multiple-Links are possible
Damage Trigger:-
Particularities:Very compact code including a complete Link-Virus within only 400 Bytes. Name of this virus is generated due to rumors that it is dropped by a lz-archiver.
Similarities:-

Agents

Countermeasures:all of the above
Standard means:VT2.58

Acknowledgements

Location:Virus Test Center, University Hamburg, FRG
Classification by:S. Freitag
Documentation by:S. Freitag
Date:14.12.1993
Information Source:Reverse-Analysis of Virus-Code, Heiner Schneegold

(c) 1996 Virus-Test-Center, University of Hamburg