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- *********************************************
- *** Reports collected and collated by ***
- *** PC-Virus Index ***
- *** with full acknowledgements ***
- *** to the authors ***
- *********************************************
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- EDV Boot Virus
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- This is a forward from John McAfee:
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- Dave Chess (of IBM) sent us another new virus that uses "creative"
- techniques to avoid detection from scanning type programs. Dave
- calls it the EDV virus. The virus infects boot sectors of floppy
- diskettes and the partition table (master boot record) of hard disks
- -- similar to the STONED virus. It saves the original boot sector
- and if any program attempts to read the boot sector, the virus
- intercepts the read and retrieves the original boot sector instead.
- Thus the system will appear normal even if infected. This technique
- is not new. The Pakistani BRAIN was the first virus to use this
- avoidance technique. What is new about this virus is that it also
- avoids detection from a memory scan. The virus accomplishes this
- feat by intercepting the clock tic and at each tic the virus
- interrogates ES and DS to determine if anyone is looking at the
- virus code. If someone is looking, the virus hangs the system.
-
- All these new detection avoidance techniques can of course be
- circumvented. They do require development time, however, and are
- becoming a nuisance. We have opted in SCAN not to block the timer
- interrupt (the obvious bypass to circumvent this virus) due to
- potential problems with time dependent background code. Instead,
- we've chosen to outrun the virus using our own "creative" memory
- scan. Seems to work so far and will be included in V58 of SCAN - -
- due out Feb 15th -- if beta testing goes well.
-
- John McAfee ...................
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