Working with the Windows Desktop and File System
Transcript of Working with the Windows Desktop and File System
Copyright © 2005 Heathkit Company, Inc. All rights reserved.
Unit 4
Working with the
Windows Desktop
and File System
55
File Extensions
• Extensions control how a file is
opened.
• By default, you can’t see file
extensions.
• Extensions are displayed for
unregistered file types.
65
A Virus is...
• An intentionally destructive computer program.
• Human generated vs. machine generated.
• Somebody’s illness they intentionally give to you and hope you pass it on.
67
How a Virus Spreads
Hard disk driveHard Disk Drive
Infected
Floppy Disk
Virus
Virus
Virus
Floppy Disks
Virus
68
How a Virus Spreads
Hard disk driveHard Disk Drive
Virus
Virus
Virus
Floppy Disks
Virus
From Network,
BBS, or Internet
69
Where Viruses Hide
• Executable files (Parasitic Virus)
• The hard or floppy disk DOS Boot
Record (Boot Sector Virus)
• Hard disk partition record
continued...
70
Where Viruses Hide
• Added to end of legitimate
program.
• In unused memory areas
• In a disk sector.
• In memory - TSRs
71
Parasitic Viruses
Attach themselves to
executable programs and
do their dirty work when
that program is run.
82
How a Virus Works...
• Your system “catches” the virus.
• The virus activates.
• The Worm spreads the virus
83
Macro Virus• Probably most common virus today.
• Open doc with Macro and you’ve got it.
• Often found in Word and Excel docs.
• Written in the app’s macro language.
• Easy to spread.
• Transferred over the internet.
• Macro languages are easy to learn.
86
HD
Win 98
Boot Disk
HD
Win 98
Boot Disk
HD
Win 98
Boot Disk
HD
Win 98
Boot Disk
My
Important
Data
Regular Backups are More
Important than any Virus
Protection Procedures
87
Use Software Only From
Reputable Sources...
• Don’t use pirated software.
• Don’t borrow software.
• Don’t loan software.
• Make sure you have the original software distribution disks -floppies, CD-ROM, etc.
88
Use a Virus Scanner Regularly
• Get the latest virus definitions from WWW.
• Educate users in using virus scanning
software.
• Scan diagnostic and boot disks regularly.
90
Have a Quarantine Machine
for Disk Testing
• Scan disks on quarantine machine.
• Load the disk contents onto
quarantine machine HDD and scan.
• Cold boot quarantine computer from
your EBD and check hard disk.
92
If you get a virus...
• Ignore messages saying “Do not
turn this computer off or the data
will be destroyed”.
• Cold boot from the EBD, run
scanner and clean infected files.
• Scan any recently used floppies.