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