Trojan:Win32/Nebular.gen!D is a trojan that gathers information from the affected machine and sends it to remote sites. It has been distributed as an executable file that is approximately 43,000 to 47,000 in size (depending on the small differences across minor variants).
System Changes
The following system changes may indicate the presence of Trojan:Win32/Nebuler.gen!D:
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The presence of the following files:
%userprofiletemp%\twe[one random character].tmp
%userprofiletemp%\twe[one random character].bat (same filename as used above, for example twec.tmp and twec.bat).
<system folder>\win[three random characters]32.dll file. (for example winjte32.dll)
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The presence of the following registry modifications:
Adds value: "Asynchronous"
With data: "1"
To subkey: HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\Notify\<trojan DLL minus .dll extension>
Adds value:"C:\Program Files\Internet Explorer\iexplore.exe"
With data: "internet explorer"
To subkey: HKCU\Software\Microsoft\Windows\ShellNoRoam\MUICache
Adds value:"NodeSlots"
With data: ""
To subkey:HKCU\Software\Microsoft\Windows\ShellNoRoam\BagMRU
Adds value:"Locked"
With data: "1"
To subkey: HKCU\Software\Microsoft\Internet Explorer\Toolbar
Adds value:"Order"
With data: "."
To subkey: HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\MenuOrder\Favorites\Links
- The presence of the following registry keys:
HKLM\SOFTWARE\Microsoft\MSSMGR\Data
HKLM\SOFTWARE\Microsoft\MSSMGR\LSTV
HKLM\SOFTWARE\Microsoft\MSSMGR\BSTV
HKLM\SOFTWARE\Microsoft\MSSMGR\PSTV
HKLM\SOFTWARE\Microsoft\MSSMGR\SSTV
HKLM\SOFTWARE\Microsoft\MSSMGR\SSLIST
Trojan:Win32/Nebular.gen!D is a trojan that gathers information from the affected machine and sends it to remote sites. It has been distributed as an executable file that is approximately 43,000 to 47,000 in size (depending on the small differences across minor variants).
Installation
When executed Trojan:Win32/Nebular.gen!D creates a mutex that consists of 4 ascii digits, for example "1006", or "3002" (this mutex differs across minor variants of the trojan). If the mutex already exists, the trojan terminates.
If the mutex does not already exist, the trojan drops the following files:
- %userprofiletemp%\twe[one random character].tmp
- %userprofiletemp%\twe[one random character].bat (same filename as used above, for example twec.tmp and twec.bat). This batch file is used to delete the .tmp file and itself.
- <system folder>\win[three random characters]32.dll file. (for example winjte32.dll)
Note - <system folder> and %userprofiletemp% refer to variable locations that are determined by the malware by querying the Operating System. The default installation location for the System folder for Windows 2000 and NT is C:\Winnt\System32; and for XP and Vista is C:\Windows\System32. Whereas %userprofiletemp% is normally located at %UserProfile%\Local Settings\Temp
The trojan also drops an additional batch file in the current directory to delete both its original executable and the batch file itself.
Trojan:Win32/Nebular.gen!D launches a hidden instance of iexplore and injects the dropped dll into the iexplore process space.
The trojan also modifies the following registry entry in order to run on every start up:
Adds value: "Asynchronous"
With data: "1"
To subkey: HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\Notify\<trojan DLL minus .dll extension>
It encodes and stores information for its own use in the following keys:
HKLM\SOFTWARE\Microsoft\MSSMGR\Data
HKLM\SOFTWARE\Microsoft\MSSMGR\LSTV
HKLM\SOFTWARE\Microsoft\MSSMGR\BSTV
HKLM\SOFTWARE\Microsoft\MSSMGR\PSTV
HKLM\SOFTWARE\Microsoft\MSSMGR\SSTV
HKLM\SOFTWARE\Microsoft\MSSMGR\SSLIST
The trojan also makes the following further modifications to the registry:
Adds value:"C:\Program Files\Internet Explorer\iexplore.exe"
With data: "internet explorer"
To subkey: HKCU\Software\Microsoft\Windows\ShellNoRoam\MUICache
Adds value:"NodeSlots"
With data: ""
To subkey:HKCU\Software\Microsoft\Windows\ShellNoRoam\BagMRU
Adds value:"Locked"
With data: "1"
To subkey: HKCU\Software\Microsoft\Internet Explorer\Toolbar
Adds value:"Order"
With data: "."
To subkey: HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\MenuOrder\Favorites\Links
Using the dropped DLL, the trojan creates the mutex 'm3d5rt10' to avoid running multiple copies of itself in memory.
Payload
Collects Information
Trojan:Win32/Nebular.gen!D collects hardware information from the affected machine and sends it to the following sites:
- smart-security.biz
- searchmeup.biz
Collected information may include the affected machine's Media Access Control (MAC) address, Volume Serial Number, Brand, Version and a Unique ID of an RAS capable device, (which would normally be a modem).
The trojan is also able to update itself through from the URLs listed above.
Analysis by Oleg Petrovsky
Take the following steps to help prevent infection on your system:
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Enable a firewall on your computer.
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Get the latest computer updates for all your installed software.
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Use up-to-date antivirus software.
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Use caution when opening attachments and accepting file transfers.
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Use caution when clicking on links to web pages.
Enable a firewall on your computer
Use a third-party firewall product or turn on the Microsoft Windows Internet Connection Firewall.
To turn on the Windows Firewall in Windows Vista
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Click Start, and click Control Panel.
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Click Security.
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Click Turn Windows Firewall on or off.
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Select On.
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Click OK.
To turn on the Internet Connection Firewall in Windows XP
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Click Start, and click Control Panel.
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Click Network and Internet Connections. If you do not see Network and Internet Connections, click Switch to Category View.
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Click Change Windows Firewall Settings.
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Select On.
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Click OK.
Get the latest computer updates
Updates help protect your computer from viruses, worms, and other threats as they are discovered. It is important to install updates for all the software that is installed in your computer. These are usually available from vendor websites.
You can use the Automatic Updates feature in Windows to automatically download future Microsoft security updates while your computer is on and connected to the Internet.
To turn on Automatic Updates in Windows Vista
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Click Start, and click Control Panel.
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Click System and Maintainance.
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Click Windows Updates.
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Select a setting. Microsoft recommends selecting Install updates automatically and choose a time that is convenient for you. If you do not choose Automatic, but you choose to be notified when updates are ready, a notification balloon appears when new downloads are available to install. Click the notification balloon to review and install the updates.
To turn on Automatic Updates in Windows XP
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Click Start, and click Control Panel.
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Click System.
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Click Automatic Updates.
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Select a setting. Microsoft recommends selecting Automatic. If you do not choose Automatic, but you choose to be notified when updates are ready, a notification balloon appears when new downloads are available to install. Click the notification balloon to review and install the updates.
Use up-to-date antivirus software
Most antivirus software can detect and prevent infection by known malicious software. To help protect you from infection, you should always run antivirus software that is updated with the latest signature files. Antivirus software is available from several sources. For more information,
see http://www.microsoft.com/protect/computer/viruses/vista.mspx.
Use caution when opening attachments and accepting file transfers
Exercise caution with e-mail and attachments received from unknown sources, or received unexpectedly from known sources. Use extreme caution when accepting file transfers from known or unknown sources.
Use caution when clicking on links to web pages
Exercise caution with links to web pages that you receive from unknown sources, especially if the links are to a web page that you are not familiar with or are suspicious of. Malicious software may be installed in your system simply by visiting a web page with harmful content.
