TechMag

Date: 09/07/2004 by Thejesh GN Issue: 28

Let’s dissect a virus? --1
All of us at one or other point of life would have faced virus. Now let us know what is virus, how does it spread across, how does it work etc. in detail. This article is a sort of small tutorial about virus. Along with the tutorial let us see an example code which makes reading interesting. I have not decided how long this article should it may span across 3 to 4 editions. And I would like to bring to your notice that what ever discussed in this article is only for educational purpose. I don’t guarantee anything will work nor do I take any responsibility of damages due to use of this article; you are free to do anything at your own risk. That’s enough of warnings lets start,

Virus is a piece of code which can spread, protect itself from detectors and do its duty silently. Well the duty differs from virus to virus depends on the intensions of coder. It may vary from harmless displaying of a popup to deleting all files on your drive. The possibilities are wide open and the limitation is your (??) imagination.

Most of the virus which I have seen or heard is written for windows. Usually coded in C or VB script. But you can find the virus batch program too. Macro viruses are written in VB script which is shipped along with Office suite. Ultimately the choice depends on what virus should do.

The virus may have the following characteristics:

Spreading - access the address book and send a copy of itself as an attachment, put a copy of itself on floppy disk or other drives, if the virus is in floppy disk then put a copy of itself on hard disk etc.
Disguise – hide it self so that user or other software’s can’t find it. Follow the naming convention similar to system/OS files. Make a copy of itself in system folders so that users don’t doubt. Have backups at different places. Attack when you get a chance.
Empower itself – Like downloading some more code or other stuff from net. Get privileges to run other programs.
Make space for siblings - Downloading the latest version of itself (better genes), Remove/weaken the security so that later versions can be more effective.
Routine – start working as soon as machine boots up, as soon as some other program is started or on any other event.
Job – do its job like deleting the file, or mail some sensitive data or make some other program inactive etc.

So doesn’t it match the biological virus? They too have the danger of getting eliminated by user or detectors. ‘Survival of Fittest’ applies here too. They should be able to survive and grow in hostile conditions. They should improve/evolve continuously to survive.

Let’s see a code example in the next issue. Have any ideas mail me.

Java Expert Java magazines.
Hey I found a new website where they post really good advanced java and related topics. If you are interested you can visit the site at

www.javaranch.com . They have magazine too but they post it on their web site once a month. But they post a mail when ever an edition is released.

Another very good java magazine which I am following is JavaSpecialists’ Newsletter. You can subscribe to it at http://www.javaspecialists.co.za. All previous issues are available online.

Linux Tips History substitution.
Command lines are usually saved in a history file before they are executed. You can see your previous commands by typing

$ history

1 clear

2 ls

The result will show all the commands which you have run. You can rerun a command in the history file by typing

$ r 1 # for Korn shell or

$ r: !1 # for c shell

The no (here 1) is the no associated with the command in the history file which you want to rerun.

If you have any tips and like to share it. Then send it to my e-mail id.

Editors Note: TechMag completes one year.
Hi All,

I am very happy inform you that TechMag is one year old now. It all started on one boring day 25^th June 2003, I initially sent it to few of my friends. When the list of receivers started growing I thought it’s easy to maintain if I have a list hence I created group in Yahoo. Now we have around 70 subscribers and still growing. Thanks to all TechMag readers. Keep sending your mails.
If this newsletter was forwarded to you, you can subscribe to it by sending a mail to subscription id given at the end of mail .Please forward it to any of your friends if they are interested in such magazine.

Thanks and rgds,
Thejesh GN.
thej at techie dot com

DISCLAIMER: The ideas expressed in this newsletter are solely mine. While stating this I do not represent anybody.

The articles presented in this magazine are only for educational purpose. And you can use at your own risk.
Copy left Thejesh GN 2004

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