How can you find a computer virus without any antivirus software?

Answer 1

Its not possible to find a virus file on your computer without using anti-virus software, so try downloading some full anti-virus software.

However, it is possible to scan for viruses without having a virus scanner installed on your computer.

If windows is functional on your computer, there is a free virus scanner available from Microsoft (XP or newer) at the Microsoft security essentials site. See link in the related links section below.

If you cannot boot normally you may have to resort to scanning your hard drive from another operating system.

Luckily, modern machines can boot-up from CD's. A LIVE-CD can be used to boot most machines, and scan from the CD's Operating system. There are some restrictions, many LIVE-CD's require 256MB of ram, and fairly standard hardware.

Use a different machine to downloaded and burn the software on a CD, then use that to clean the hard-drive on your machine.

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An example process using system rescue CD on a machine that has network access to the internet:

boot machine with systemrescuecd

choose normal 32 bit boot ( or whatever is appropriate for your machine )

choose keyboard layout (41 for USA)

when the prompt comes up type fsarchiver probe simple [enter] you'll see this:

root@sysresccd /root % fsarchiver probe simple

[======DISK======] [===========NAME============] [====SIZE====] [MAJ] [MIN]

[sda ] [ST340016A ] [ 37.27 GB] [ 8] [ 48]

[=====DEVICE=====] [==FILESYS==] [======LABEL======] [====SIZE====] [MAJ] [MIN]

[loop0 ] [squashfs ] [ ] [ 220.33 MB] [ 7] [ 0]

[sda1 ] [vfat ] [DellUtility ] [ 31.35 MB] [ 8] [ 65]

[sda2 ] [ntfs ] [MainDisk ] [ 37.24 GB] [ 8] [ 66]

look for the device with the volume name of your WINDOWS hard drive

(Yours is most likely /dev/sda1, but on my machine it is /dev/sda2)

Only run ONE of the following two commands substituting your appropriate device name:

If it is listed as having a filesystem ntfs:

run this: ntfs-3g /dev/sda1 /mnt/windows

-----OR----

If it is listed as having a vfat filesystem

run this: mount -t vfat /dev/sda1 /mnt/windows

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run ifconfig eth0 to verify your network is active:

root@sysresccd /root % ifconfig eth0

eth0 Link encap:Ethernet HWaddr 00:a0:cc:e4:88:ab

inet addr:192.168.10.100 Bcast:192.168.10.255 Mask:255.255.255.0

......

The important bit is that you have an active inet addr: if not, you may have to run net-setup (but that is a different question and answer)

Next run: freshclam

Then run clamscan -r -i /mnt/windows

Any viruses found will be reported to you, but you must be patient, this will take a long time.

Oh, and congratulations, you are now a Linux newbie! (at least)