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recently I found back door on my laptop. I t was generating many files with random names only 2-3 characters only. The most of them is empty. How can I find files only with 1 to 3 characters generated in the last 30 days? Thanks Arman.

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migrated from May 16 '10 at 15:48

This question came from our site for system and network administrators.

up vote 7 down vote accepted

Use the search facility in Windows Explorer and use the '?' wildcard character.

Search for files names matching ?, ?? and ???. If the files have extensions, try ?.*, ??.* and ???.*.

You can also specify the created date.

If your laptop has/had a backdoor, you really should be less concerned with the files on the system and more concerned with reinstalling your laptop, as it is the only sure way to close the back door and remove any root kits.

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+1 nuke it from orbit. It's the only way to be sure. Don't expect anti-virus software to reliably remove all today's huge range of stealthy malware. 'Cos it won't. It'll just give you a nice false sense of security. – bobince May 16 '10 at 12:42
@Bryan: the method '??' does not find the files. but I can see in the windows/system32/ file named: 'hÏ'. – Arman May 16 '10 at 13:30
@Bryan: Well the double quotes "??" are solving the problem. Maybe it depends on locals? I am using the French WinXP. – Arman May 16 '10 at 13:32
@bobince: Yes, I agree with the clean install, but it is not always possible to reinstall all packages. – Arman May 16 '10 at 13:34
@Arman: Sorry, I didn't explain that very well, don't use any quotes as part of your search string. I've removed them from my answer and used highlighting instead. – Bryan May 16 '10 at 14:04

I think that this would work:

C:\>dir /s/b ???
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It's probably easier to find empty files generated in the last 30 days.

Go to Start menu - Search

Click When was it modified select Past month or manually pick the dates.

Click What size is it select Specify size at most 1KB

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Using Powershell:

$date = get-date

$olddate = $date.adddays(-30)

get-childitem -path c:\ -Recurse | where-object {$_.basename.length -lt "4" -and $_.creationtime -gt $olddate}
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