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Trojan:W32/DNSChanger.ARNF

Classification

Category:Malware
Type:Trojan
Platform:W32
Aliases:

Trojan:W32/DNSChanger.ARNF, Trojan:W32/DNSChanger.ARNF, Worm.Win32.AutoRun.udt, TR/Crypt.XPACK.Gen (Avira), Trojan:​Win32/Alureon.gen!J (Microsoft)

Summary

A trojan, or trojan horse, is a seemingly legitimate program which secretly performs other, usually malicious, functions. The program is often started by the user, and it does not usually replicate.

Removal

Based on the settings of your F-Secure security product, it will either move the file to the quarantine where it cannot spread or cause harm, or remove it.

A False Positive is when a file is incorrectly detected as harmful, usually because its code or behavior resembles known harmful programs. A False Positive will usually be fixed in a subsequent database update without any action needed on your part. If you wish, you may also:

  • Check for the latest database updates

    First check if your F-Secure security program is using the latest updates, then try scanning the file again.

  • Submit a sample

    After checking, if you still believe the file is incorrectly detected, you can submit a sample of it for re-analysis.

    Note: If the file was moved to quarantine, you need to collect the file from quarantine before you can submit it.

  • Exclude a file from further scanning

    If you are certain that the file is safe and want to continue using it, you can exclude it from further scanning by the F-Secure security product.

    Note: You need administrative rights to change the settings.

Technical Details

This malicious software is dropped onto the system by Trojan-Dropper:W32/Agent.FLN. It is used to change the DNS settings on a system so that information such as passwords and credit card details can be retrieved.

During installation, this malware creates the following files:

  • c:\autorun.inf - contains the autostart routine for c:\resycled\boot.com
  • c:\resycled\boot.com - detected as Trojan:W32/DNSChanger.ARNF

It also creates this directory:

  • c:\resycled

Execution

Once installed, this malware attempts to connect to a website via HTTP POST:

  • https://94.247.2.104/[...]/generator

It is capable of changing the DNS settings in the machine to:

  • 85.255.115.237
  • 85.255.112.201.

Registry Modifications

Sets these values:

  • HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Windows\ControlActiveService = Spooler
  • HKEY_LOCAL_MACHINE\SOFTWARE\Classes\msqpdxvxmsqpdxrun = dword:00000047msqpdxpff =msqpdxaff =msqpdxinfo =msqpdxid = "rfx ||fcegeea "msqpdxsrv = dword:6802f719
  • HKEY_CLASSES_ROOT\msqpdxvxmsqpdxrun = dword:00000047msqpdxpff =msqpdxaff =msqpdxinfo =msqpdxid = "rfx ||fcegeea "msqpdxsrv = dword:6802f719

Creates these keys:

  • HKEY_LOCAL_MACHINE\Software\Classes\msqpdxvx
  • HKEY_CLASSES_ROOT\msqpdxvx

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