Sunday, August 21, 2011

Virus Infection Symptoms

Some of the very common shown by a system infected by a virus are given next.

Unexpected slowdown of the System

This is one main symptom of the virus infection. If the system without any apparent reason starts to take more time to load programs from the disk or starts to operate slower than its normal speed then you can suspect a virus infection.



Decrease in the amount of available memory

This is another symptom of virus infection. When checked with the CHKDSK, the system shows some KB of memory missing from the main memory or when checked with the MEM/D/P command, the memory module list shows some program resident in the memory without any proper module name.



Increase in BAD Sectors/Lost clusters etc.

When the number of bad sector start increasing, or when the number of lost clusters reported by the SCANDISK or CHKDSK start increasing without any special reason then one main reason behind this could be a virus infection



Cannot Execute Executable Files

If you find that the executable files (.EXE, COM etc) which you are able to execute till yesterday start missing from the directories or when executing them you start getting some errors messages then this again could be one major indication of the virus attack.



Screen Shows Some Unusual Outputs

Getting of some message such as “legalize marijuana” or dropping of letter to the bottom of the screen or some special character appearing or moving of virus infection.

Another indication could be some music being played by the computer without running any special music program.

Drive’s Light Turns on

The drive’s light may turn on indicating that a read or write is taken place even when you have not given any read or write to the disk without any write command being issued are some other symptoms of virus infection.

Some software as windows keep temporary data on the disk read and writes to them periodically.


New “.COM” files appear for the “.EXE” files

This shows a companion type virus where the virus stays as a .COM file for and .EXE file. This gives the virus a chance to get executed because the DOS always executes the .COM file before executing a .EXE file of both the files are of same name.

Some DOS program and utility program contain both .COM and .EXE file with the same name. For example, the DOS program MSD (Microsoft Diagnostic) contains both MSD.COM and MSD.EXE.

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