Monday, February 28, 2011

What if you want to access files from infected usb drive or infected system

The best part of the viruses are that they are operating system dependent. In other words a virus that is written for windows operating system will not infect a linux based system. This is because of many reasons -
The difference in the file system  and the file types in both operating systems.
The autorun.inf  is identified by windows (used for autorunning executables like .bat and .exe) but is not idetified by linux os.

The good trick to access files from infected system  or infected usb drive is to use a live linux boot cd and accessing the files without any fear of virus infection. You even dont have to install it on hard disk. It is live.

There are many live boot cd/dvd available on internet.
One of them is lucid puppy 5.2  which can be easily downloaded from http://puppylinux.org/main/Download%20Latest%20Release.htm
or another version from
 http://distro.ibiblio.org/pub/linux/distributions/puppylinux/puppy-5.1.1/lupu-511.iso
 both are live bootabble cd iso image.

You can download it by using idm  http://www.internetdownloadmanager.com/download.html
and burn it using cd/dvd burner like CDBurnerXP which is a free CD, DVD, HD-DVD and Blu-Ray burning software from http://cdburnerxp.se/download

If you want to boot  the lucid puppy from usb (pen drive or memory card) and not from cd then you can use following two tools.

You can  download unetbootin from  http://unetbootin.sourceforge.net/ and run it. It will ask for the iso file . Provide it with the path of  iso file which you just downloaded. insert your usb drive (this pendrive is not the one from which you have to access the data) and backup your existing data if necessary. Unetbootin will make your usb drive bootable.

Another tool is  Universal USB Installer http://www.pendrivelinux.com/universal-usb-installer-easy-as-1-2-3/
It can also make usb bootable like unetbootin but please backup your existing  pendrive data if necessary.

Now the main trick. You have now got atleast a bootable pendrive or a bootable cd of lucid puppy linux.
Insert the bootable cd (before restarting the computer) or the bootable pendrive (after shuting down the computer). Till now dont connect the pendrive from which you have to access the data. Now restart computer and make changes to your bios settings for first boot device (either usb or cd/dvd which ever is applicable to you). After that the computer will boot and lucid puppy os will load in live environment.
Some times in some computers while booting live os , it gives errors due to the floppy drive or its controller. If this occors and live os dont boot then go to bios again by restarting your computer and set floppy disk drive to None  and/or dissable  the floppy disk controller. After that reboot and this time live os will boot.
when its desktop appears , now you can attach your pendrive from which you have to access the data.
You can also easily  access your files from your internal hard disk drive without any fear of virus infection.
Now you can easily and safely copy/move your data between your harddisk and pendrive without further infecting any of them. After your work is done , remove all your storage  media cd/usb by right clicking and unmounting them (or simply shut down and remove all). After that you can normally login to your windows as usual.  So, you can get relief of virus without using any antivirus.

All these process will not effect/modify  your harddisk or your previosly installed operating system (os) because you were in live environment.

If your computer bios dont support usb booting and you want to boot your usb then read my previous post
"older computers that can't boot from usb - the howto guide" at http://averma82.blogspot.in/2011/02/older-computers-that-cant-boot-from-usb.html

You can mail me to abhi.82@hotmail.com

Please  post any  suggestions or comments.

Sunday, February 27, 2011

Older computers that can't boot from usb - The howto guide

Before the actual technique, some details...

Most of the older computers cant boot from usb (pen drives or memory cards, ext hdd) because of the bios (basic input output system) limitations. This is because the older bios do not contain the usb drivers. So at the time of booting the usb drives are not recognized.

Generally, drivers are automatically loaded during boot process from 4 sources -
From bios itself
From addon cards or daughter cards (if additional bios is present)
From system disk or hard disk where we additionally install it after os installation
From os itself (win 7 itself has most of drivers)

If any device attached to computer requires driver, which is not present, will not work properly
So in this case the usb device do not get drivers from old bios and if you have to boot it then you have to provide it all the required usb drivers from some other source.

The easy and simple method to do this is to use the plop boot cd which contains required usb drivers for boot process to complete.

The technique -
Download plpbt-5.0.11-2.zip  from http://www.plop.at/en/bootmanager.html

Extract it to get the iso file plpbt.iso (can extract using 7zip http://www.7-zip.org/download.html )
Then burn iso file using any cd/dvd burning software like nero. This will be a bootable cd.

Now attach the usb device (containing any kind of  os for installation purpose or live environment) to the usb port of the computer (that doesn't support usb booting) and then boot it  from cd you just created.

Nearly every older pc bios contains cd drivers so cd booting in older pc is not a problem.

After booting from cd you will get a screen that shows the plop boot manager.
Then you will get a menu that has some options to choose from. There you have to choose the usb option.
When you select the usb option there, the usb drivers will be automatically loaded for bios and the usb device will get detected by bios. After that the usb device will start booting. then you can eject the tray and take out the cd. This will not effect the usb boot process.

The plop boot manager do not permanently change or modify the bios. It is a temporary process. That means in future if you have to boot from usb  device again then you have to repeat the whole process.

If the usb device do not boot with this process the check the device itself. May be the pendrive itself is not bootable or there something wrong in the os that is inside the usb.
In that case again prepare your pendrive properly and try again.

You can mail me to abhi.82@aol.in

Please  post any  suggestions or comments.