F-Secure
Tools
Email-Worm:W32/Agent.EV
Summary
Email-Worm.Win32.Agent.ev arrives on systems as an e-mail attachment and attempts to download additional components onto the system if executed.
Additional Details
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:
The attachment is named Saver.zip.
When the malware is extracted and executed, it will drop the following components:
%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 as
Trojan-Downloader:W32/Agent.NSL.
The following registry entries are created to load WinNt32.dll on every system startup:
The following registry entries are created to start the [name].sys file as a service:
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:
Other slightly modified variants may attempt to connect to different addresses.
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 as
Trojan-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\WinNt32
DLLName = WinNt32.dll
StartShell = WLEventStartShell
Impersonate = 00000000
Asynchronous = 00000000
ID = 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 = 00000001
Start = 00000003
ErrorControl = 00000000
ImagePath = 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.