Wednesday, November 26, 2008

Actions can take to protect computer systems

Adopt the following practices for protecting your system from various attacks:
1. Consult your system support personnel.
2. Use virus protection software
3. Use a firewall
4. Don’t open unknown email attachments
5. Don’t run programs of unknown origin
6. Disable hidden filename extensions
7. Keep all applications (including your operating system) patched
8. Turn off your computer or disconnect from the network when not in use
9. Disable Java, JavaScript, and ActiveX if possible
10. Disable scripting features in email programs
11. Make regular backups of critical data
12. Make a boot disk in case your computer is damaged or compromised
Consult your system support personnel if you work from home
If you use your broadband access to connect to your employer's network via a Virtual Private Network (VPN) or other means, your employer may have policies or procedures relating to the security of your home network. Be sure to consult with your employer's support personnel, as appropriate, before following any of the steps outlined in this document.

Use virus protection software
Be sure to keep your anti-virus software up-to-date. Many anti-virus packages support automatic updates of virus definitions. Use these automatic updates when available.

Use a firewall
It is recommend the use of some type of firewall product, such as a network appliance or a personal firewall software package. Intruders are constantly scanning home user systems for known vulnerabilities. Network firewalls (whether software or hardware-based) can provide some degree of protection against these attacks. However, no firewall can detect or stop all attacks, so it’s not sufficient to install a firewall and then ignore all other security measures.

Don't open unknown email attachments
Before opening any email attachments, be sure you know the source of the attachment. It is not enough that the mail originated from an address you recognize. If you must open an attachment before you can verify the source, we suggest the following procedure:
Be sure your virus definitions are up-to-date
Save the file to your hard disk
Scan the file using your anti virus software
Open the file
For additional protection, you can disconnect your computer's network connection before opening the file.

Don't run programs of unknown origin
Never run a program unless you know it to be authored by a person or company that you trust. Also, don't send programs of unknown origin to your friends or co-workers simply because they are amusing -- they might contain a Trojan horse program.

Disable hidden filename extensions
Windows operating systems contain an option to "Hide file extensions for known file types". The option is enabled by default, but you can disable this option in order to have file extensions displayed by Windows. After disabling this option, there are still some file extensions that, by default, will continue to remain hidden.
There is a registry value which, if set, will cause Windows to hide certain file extensions regardless of user configuration choices elsewhere in the operating system. The "NeverShowExt" registry value is used to hide the extensions for basic Windows file types. For example, the ".LNK" extension associated with Windows shortcuts remains hidden even after a user has turned off the option to hide extensions.

Keep all applications, including your operating system, patched
Vendors will usually release patches for their software when a vulnerability has been discovered. Most product documentation offers a method to get updates and patches. You should be able to obtain updates from the vendor's web site. Read the manuals or browse the vendor's web site for more information.
Some applications will automatically check for available updates, and many vendors offer automatic notification of updates via a mailing list. Look on your vendor's web site for information about automatic notification. If no mailing list or other automated notification mechanism is offered you may need to check periodically for updates.

Turn off your computer or disconnect from the network when not in use
Turn off your computer or disconnect its Ethernet interface when you are not using it. An intruder cannot attack your computer if it is powered off or otherwise completely disconnected from the network.
Disable Java, JavaScript, and ActiveX if possible
Be aware of the risks involved in the use of "mobile code" such as ActiveX, Java, and JavaScript. A malicious web developer may attach a script to something sent to a web site, such as a URL, an element in a form, or a database inquiry. Later, when the web site responds to you, the malicious script is transferred to your browser.
The most significant impact of this vulnerability can be avoided by disabling all scripting languages. Turning off these options will keep you from being vulnerable to malicious scripts. However, it will limit the interaction you can have with some web sites.

Make regular backups of critical data
Keep a copy of important files on removable media such as ZIP disks or recordable CD-ROM disks (CD-R or CD-RW disks). Use software backup tools if available, and store the backup disks somewhere away from the computer.

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