Backdoor: W32/Duqu

Summary

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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.

Removal

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Automatic action

Once detected, the F-Secure security product will automatically disinfect the suspect file by either deleting it or renaming it.

More

More information on scanning and removal options available in your F-Secure product can be found in the Help Center.

You may also refer to the Knowledge Base on the F-Secure Community site for more information.

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Technical Details

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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.

Duqu is reportedly targeted to specific organizations, possibly with a view to collecting specific information that could be used for a later attack.

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

Installation

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.

Removal

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

More

For more information, see:

• Labs Weblog post: Duqu - Stuxnet 2
• Symantec white paper containing technical analysis: W32.Duqu - The precursor to the next Stuxnet