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Leaktest information
Website : http://www.klake.org/~jt/dnshell/
Author : Jarkko Turkulainen
Dates : April 2004 (v1.0)
Categories : : recursive request
Download : dnstester.exe (View EULA)
(sources : dnstester.zip)
MD5 4F7102D6FC15C46790F9951A4EF07D6D
SHA-160 D94A4B768F28A50532B274DD68A80C3348C35622
Operating System : Windows 2000/XP/2003



Detected by Antivirus as Trojan.Win32.Agent.pc
THIS IS NOT A VIRUS

download password protected archive (pass = leaktest)



Leaktest description
By default on NT OSs since windows 2000, a Windows service 'DNS client' is running and handles all DNS requests. Thus, all DNS requests coming from various applications you can have will be transmitted to the DNS client (SVCHOST.EXE under XP) which will, itself, do the DNS request.
This behaviour can be used to transmit data to a remote computer by crafting a special DNS request without the firewalls notice it. Indeed, the DNS client windows service must be allowed to acces the Internet. DNStester uses this kind of DNS recursive request to bypass your firewall.

=> In order to use DNStester, you must left enabled the DNS client windows service (a real trojan could kindly do it for you)


Meaning
If the test is a success, this means that your firewall checks too late DNS requests, when they want to go out the computer, and just see the DNS client windows service and not the leaktest.
If the test fails, probably your DNS client windows service is disabled, enable it before to try again.

Download DNStester Leaktest
(View EULA)



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