Chapter 33 Anti-Virus
ZyWALL USG 100/200 Series User’s Guide
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33.7 Anti-Virus Technical Reference
Types of Computer Viruses
The following table describes some of the common computer viruses.
Computer Virus Infection and Prevention
The following describes a simple life cycle of a computer virus.
1
A computer gets a copy of a virus from a source such as the Internet, e-mail, file
sharing or any removable storage media. The virus is harmless until the execution
of an infected program.
2
The virus spreads to other files and programs on the computer.
3
The infected files are unintentionally sent to another computer thus starting the
spread of the virus.
4
Once the virus is spread through the network, the number of infected networked
computers can grow exponentially.
Types of Anti-Virus Scanner
The section describes two types of anti-virus scanner: host-based and network-
based.
Table 160
Common Computer Virus Types
TYPE
DESCRIPTION
File Infector
This is a small program that embeds itself in a legitimate program. A
file infector is able to copy and attach itself to other programs that are
executed on an infected computer.
Boot Sector
Virus
This type of virus infects the area of a hard drive that a computer
reads and executes during startup. The virus causes computer crashes
and to some extend renders the infected computer inoperable.
Macro Virus
Macro viruses or Macros are small programs that are created to
perform repetitive actions. Macros run automatically when a file to
which they are attached is opened. Macros spread more rapidly than
other types of viruses as data files are often shared on a network.
E-mail Virus
E-mail viruses are malicious programs that spread through e-mail.
Polymorphic
Virus
A polymorphic virus (also known as a mutation virus) tries to evade
detection by changing a portion of its code structure after each
execution or self replication. This makes it harder for an anti-virus
scanner to detect or intercept it.
A polymorphic virus can also belong to any of the virus types discussed
above.
Summary of Contents for ZyWALL USG 100 Series
Page 2: ......
Page 30: ...Table of Contents ZyWALL USG 100 200 Series User s Guide 30 ...
Page 31: ...31 PART I User s Guide ...
Page 32: ...32 ...
Page 46: ...Chapter 2 Features and Applications ZyWALL USG 100 200 Series User s Guide 46 ...
Page 64: ...Chapter 3 Web Configurator ZyWALL USG 100 200 Series User s Guide 64 ...
Page 186: ...Chapter 7 Tutorials ZyWALL USG 100 200 Series User s Guide 186 ...
Page 223: ...Chapter 8 L2TP VPN Example ZyWALL USG 100 200 Series User s Guide 223 ...
Page 224: ...Chapter 8 L2TP VPN Example ZyWALL USG 100 200 Series User s Guide 224 ...
Page 225: ...225 PART II Technical Reference ...
Page 226: ...226 ...
Page 240: ...Chapter 9 Dashboard ZyWALL USG 100 200 Series User s Guide 240 ...
Page 284: ...Chapter 10 Monitor ZyWALL USG 100 200 Series User s Guide 284 ...
Page 372: ...Chapter 13 Interfaces ZyWALL USG 100 200 Series User s Guide 372 ...
Page 382: ...Chapter 14 Trunks ZyWALL USG 100 200 Series User s Guide 382 ...
Page 398: ...Chapter 15 Policy and Static Routes ZyWALL USG 100 200 Series User s Guide 398 ...
Page 412: ...Chapter 16 Routing Protocols ZyWALL USG 100 200 Series User s Guide 412 ...
Page 432: ...Chapter 19 NAT ZyWALL USG 100 200 Series User s Guide 432 ...
Page 437: ...Chapter 20 HTTP Redirect ZyWALL USG 100 200 Series User s Guide 437 ...
Page 438: ...Chapter 20 HTTP Redirect ZyWALL USG 100 200 Series User s Guide 438 ...
Page 460: ...Chapter 23 Authentication Policy ZyWALL USG 100 200 Series User s Guide 460 ...
Page 478: ...Chapter 24 Firewall ZyWALL USG 100 200 Series User s Guide 478 ...
Page 519: ...Chapter 25 IPSec VPN ZyWALL USG 100 200 Series User s Guide 519 ...
Page 520: ...Chapter 25 IPSec VPN ZyWALL USG 100 200 Series User s Guide 520 ...
Page 534: ...Chapter 26 SSL VPN ZyWALL USG 100 200 Series User s Guide 534 ...
Page 544: ...Chapter 27 SSL User Screens ZyWALL USG 100 200 Series User s Guide 544 ...
Page 546: ...Chapter 28 SSL User Application Screens ZyWALL USG 100 200 Series User s Guide 546 ...
Page 554: ...Chapter 29 SSL User File Sharing ZyWALL USG 100 200 Series User s Guide 554 ...
Page 639: ...Chapter 34 IDP ZyWALL USG 100 200 Series User s Guide 639 ...
Page 640: ...Chapter 34 IDP ZyWALL USG 100 200 Series User s Guide 640 ...
Page 661: ...Chapter 35 ADP ZyWALL USG 100 200 Series User s Guide 661 ...
Page 662: ...Chapter 35 ADP ZyWALL USG 100 200 Series User s Guide 662 ...
Page 694: ...Chapter 37 Content Filter Reports ZyWALL USG 100 200 Series User s Guide 694 ...
Page 712: ...Chapter 38 Anti Spam ZyWALL USG 100 200 Series User s Guide 712 ...
Page 734: ...Chapter 39 Device HA ZyWALL USG 100 200 Series User s Guide 734 ...
Page 750: ...Chapter 40 User Group ZyWALL USG 100 200 Series User s Guide 750 ...
Page 756: ...Chapter 41 Addresses ZyWALL USG 100 200 Series User s Guide 756 ...
Page 768: ...Chapter 43 Schedules ZyWALL USG 100 200 Series User s Guide 768 ...
Page 784: ...Chapter 45 Authentication Method ZyWALL USG 100 200 Series User s Guide 784 ...
Page 806: ...Chapter 46 Certificates ZyWALL USG 100 200 Series User s Guide 806 ...
Page 818: ...Chapter 48 SSL Application ZyWALL USG 100 200 Series User s Guide 818 ...
Page 828: ...Chapter 49 Endpoint Security ZyWALL USG 100 200 Series User s Guide 828 ...
Page 880: ...Chapter 50 System ZyWALL USG 100 200 Series User s Guide 880 ...
Page 920: ...Chapter 54 Reboot ZyWALL USG 100 200 Series User s Guide 920 ...
Page 922: ...Chapter 55 Shutdown ZyWALL USG 100 200 Series User s Guide 922 ...
Page 942: ...Chapter 56 Troubleshooting ZyWALL USG 100 200 Series User s Guide 942 ...
Page 954: ...Chapter 57 Product Specifications ZyWALL USG 100 200 Series User s Guide 954 ...
Page 1126: ...Appendix F Open Software Announcements ZyWALL USG 100 200 Series User s Guide 1126 ...