Trojan.Win32.Qhost.b

Technical Details

This Trojan is designed to modify the mapping of domain names to IP addresses. It is a Windows PE EXE file. It is 20 585 bytes in size. It is written in Borland Delphi. It is packed using FSG. The unpacked file is approximately 70KB in size.

Payload

This Trojan is a modified Windows %System%\drivers\etc\hosts file, which is used to map domain names (DNS) to IP addresses. The following strings are added to the hosts file.

127.0.0.1 http://downloads4.kaspersky-labs.com
127.0.0.1 http://downloads3.kaspersky-labs.com
127.0.0.1 http://downloads2.kaspersky-labs.com
127.0.0.1 http://downloads1.kaspersky-labs.com
127.0.0.1 ftp://downloads4.kaspersky-labs.com
127.0.0.1 ftp://downloads3.kaspersky-labs.com
127.0.0.1 ftp://downloads2.kaspersky-labs.com
127.0.0.1 ftp://downloads1.kaspersky-labs.com
127.0.0.1 downloads-us1.kaspersky-labs.com
127.0.0.1 rads.mcafee.com
127.0.0.1 http://www.secuser.com
127.0.0.1 a188.x.akamai.net
127.0.0.1 liveupdate.symantecliveupdate.com
127.0.0.1 liveupdate.symantec.com
127.0.0.1 liveupdate.symantec.d4p.net
127.0.0.1 update.symantec.com
127.0.0.1 ftp.nai.com
127.0.0.1 www.grisoft.cz
127.0.0.1 www.grisoft.com
127.0.0.1 free.grisoft.cz
127.0.0.1 tds.diamondcs.com.au
127.0.0.1 ieupdate.gdata.de
127.0.0.1 ieupdate6.gdata.de
127.0.0.1 ieupdate5.gdata.de
127.0.0.1 ieupdate4.gdata.de
127.0.0.1 ieupdate3.gdata.de
127.0.0.1 ieupdate2.gdata.de
127.0.0.1 ieupdate1.gdata.de
127.0.0.1 www.iavs.cz
127.0.0.1 download7.avast.com
127.0.0.1 download6.avast.com
127.0.0.1 download5.avast.com
127.0.0.1 download4.avast.com
127.0.0.1 download3.avast.com
127.0.0.1 download2.avast.com
127.0.0.1 download1.avast.com
127.0.0.1 upgrade.bitdefender.com
127.0.0.1 windowsupdate.microsoft.com
127.0.0.1 www.lavasoftusa.com
127.0.0.1 www.a-2.org
127.0.0.1 updates.a-2.org
127.0.0.1 niuone.norman.no
127.0.0.1 www.diamondcs.com.au
127.0.0.1 www.attechnical.com
127.0.0.1 www.zeylstra.nl
127.0.0.1 fractus.mat.uson.mx
127.0.0.1 www.toonbox.de
127.0.0.1 radius.turvamies.com
127.0.0.1 diamondcs.fileburst.com
127.0.0.1 downloads.My-eTrust.com
127.0.0.1 acs.pandasoftware.com
127.0.0.1 v4.windowsupdate.microsoft.com
127.0.0.1 www.NoAdware.net
127.0.0.1 www.nod32.com
127.0.0.1 www.eset.sk
127.0.0.1 avu.zonelabs.com
127.0.0.1 retail.sp.f-secure.com
127.0.0.1 retail01.sp.f-secure.com
127.0.0.1 retail02.sp.f-secure.com
127.0.0.1 www.moosoft.com
127.0.0.1 secuser.model-fx.com
127.0.0.1 secuser.com
127.0.0.1 downloads-eu1.kaspersky-labs.com
127.0.0.1 downloads2.kaspersky-labs.com
127.0.0.1 downloads4.kaspersky-labs.com
127.0.0.1 downloads1.kaspersky-labs.com
127.0.0.1 pccreg.antivirus.com
127.0.0.1 dl1.antivir.de
127.0.0.1 dl2.antivir.de
127.0.0.1 dl3.antivir.de
127.0.0.1 dl4.antivir.de

The modifications made to %System%\drivers\etc\hosts make it impossible to access the resources listed above from the victim machine.

Removal instructions

If your computer does not have an up-to-date antivirus, or does not have an antivirus solution at all, follow the instructions below to delete the malicious program:

1. Delete the original Trojan file (the location will depend on how the program originally penetrated the victim machine).
2. Modify the %System%\drivers\etc\hosts file using any standard application (e.g. Notepad). Delete the strings added by the Trojan. The original hosts file has the following contents:

   # Copyright (c) 1993-1999 Microsoft Corp.
   #
   # This is a sample HOSTS file used by Microsoft TCP/IP for Windows.
   #
   # This file contains the mappings of IP addresses to host names. Each
   # entry should be kept on an individual line. The IP address should
   # be placed in the first column followed by the corresponding host name.
   # The IP address and the host name should be separated by at least one
   # space.
   #
   # Additionally, comments (such as these) may be inserted on individual
   # lines or following the machine name denoted by a '#' symbol.
   #
   # For example:
   #
   # 102.54.94.97 rhino.acme.com # source server
   # 38.25.63.10 x.acme.com # x client host
   
   127.0.0.1       localhost
   

3. Update your antivirus databases and perform a full scan of the computer (download a trial version of Kaspersky Anti-Virus).