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Backdoor:W32/Duqu, Backdoor:W32/Duqu.A, Backdoor:W32/Duqu.B w32.Duqu (Symantec)


Backdoor:W32/Duqu silently installs files on the infected system, then collects and forwards the confidential information from the system to a remote Command and Control (CC) server. Duqu is reportedly targeted to specific organizations, possibly with a view to collecting specific information that could be used for a later attack.


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

Backdoor:W32/Duqu's source code appears to be closely related to that of Stuxnet. Unlike Stuxnet, Duqu's payload appears to be related to information gathering.

Multiple Duqu variants have reportedly been identified, though functional similarities between all the variants have yet to be confirmed.


The A variant of this malware drops the following files:

  • %Windows%\system32\Drivers\jminet7.sys - loader driver componet
  • %SystemDrive%\inf\netp191.pnf - encrypted main DLL component
  • %SystemDrive%\inf\netp192.pnf - encrypted configuration file

Similar to Stuxnet, Duqu's driver files are signed with certificates stolen from a Taiwanese company.

The malware then creates the following launch point:

  • HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\JmiNET3

The driver is loaded during system start-up and will be responsible for decrypting and loading the main DLL component.

The B variant of this malware uses different filenames (cmi4432.sys, cmi4432.pnf and cmi4464.PNF, respectively) and a differently-named launchpoint (HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\cmi4432), but further functionality appears to be the same.

Remote Communication

On successful installation, Duqu attempts to connect to a remote CC server, which may allow the attackers to update the installed components, download additional components onto the system, retrieve collected information and issue further commands.

It was reported that a standalone spying component (which we categorize as a trojan-spy) was recovered on an infected system. It was probably downloaded by the malware at some point in time. We detect the trojan-spy generically.

The trojan-spy is able to record keystrokes and collect various details of system information. The collected information is saved to an encrypted file, which the attackers can retrieve via the CC server.


Duqu is reportedly configured to run for 36 days, after which it will automatically remove itself from the system.


For more information, see: