Email-Worm:W32/Agent.EV

Classification

Malware

Email-Worm

W32

Email-Worm:W32/Agent.EV

Summary

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

Removal

Automatic action

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.

Suspect a file is incorrectly detected (a False Positive)?

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 detection database 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.

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Submit a sample

Submit a file or URL for further analysis.

Technical Details

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

The following email 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.