Email-Worm: ​W32/Agent.EV

Summary

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Email-Worm.Win32.Agent.ev arrives on systems as an e-mail attachment and attempts to download additional components onto the system if executed.

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.

Contact Support

For further assistance, F-Secure customers can request support online via the Request support or the Chat forms on our Home - Global site.

Technical Details

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Email-Worm:W32/Agent.EV spreads as an attachment in spam e-mail with attention grabbing lines in the subject field.

The following e-mail subjects have been observed:

• Hot News
• Hot Pictures
• Paris Hilton
• Something Hot

The attachment is named Saver.zip.

When the malware is extracted and executed, it will drop the following components:

• %Windir%\System32\WinNt32.dll
• %Windir%\System32\WinData.cab\
• %Windir%\System32\drivers\[name].sys

%Windir% is the Windows directory. This is usually C:\Windows.[name] is a random filename. Observed examples are Mvd37.sys and Irv31.sys. The contents of the files are the same.WinData.cab is a copy of WinNt32.dll.

All of the dropped components are detected asTrojan-Downloader:W32/Agent.NSL.

The following registry entries are created to load WinNt32.dll on every system startup:

• HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\Notify\WinNt32DLLName = WinNt32.dllStartShell = WLEventStartShellImpersonate = 00000000Asynchronous = 00000000ID = 0000003C

The following registry entries are created to start the [name].sys file as a service:

• HKLM\SYSTEM\CurrentControlSet\Control\SafeBoot\Minimal\[name].sys (default) = Driver
• HKLM\SYSTEM\CurrentControlSet\Control\SafeBoot\Network\[name].sys (default) = Driver
• HKLM\SYSTEM\CurrentControlSet\Services\[name]Type = 00000001Start = 00000003ErrorControl = 00000000ImagePath = System32\drivers\[name].sys

Similar changes are made in HKLM\SYSTEM\ControlSet001\Services\[name] and HKLM\SYSTEM\ControlSet002\Services\[name].

The Trojan-Downloader:W32/Agent.NSL DLL component will then attempt to connect to one of the following addresses:

• 66.232.113.80
• 208.66.195.15

Other slightly modified variants may attempt to connect to different addresses.