Worm:Win32/Samael.A is a worm that spreads in all writeable drives in the system. It modifies the system's NTLDR file, which is a Windows boot file, in such a way that may possibly lock the user out of the system. It also drops another malware in the system.
Installation
Upon execution, Worm:Win32/Samael.A drops the following files:
- %windir%\smms.exe - copy of the worm
- %windir%\inf\csrss.exe - copy of the worm
- %windir%\inf\diskini.xp - copy of the worm
- %windir%\smss.bat - detected as Worm:BAT/Samael.A; it is a batch file used to shut down the system
Note that a Windows file named csrss.exe exists by default in the Windows system folder.
It also modifies the system registry so that it runs every time Windows starts:
Adds value: "Proyecto1"
With data: "%windir%\smms.exe"
To subkey: HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
It also creates the file %ProgramFiles%\emule\incoming\[traffik]Crack for windows.sik, which contains the following strings:
Samael 3.0
<system time>
<system date>
<system language>
Spreads Via...
Logical Drives
Worm:Win32/Samael.A spreads by dropping copies of itself as info.exe in all logical drives, such as mapped and removable drives. It also drops a corresponding autorun.inf file, which enables its dropped copy to run whenever the drive is accessed and Autorun is enabled.
Payload
Modifies System File
Worm:Win32/Samael.A modifies the Windows boot file
%Systemdrive%\ntldr. The modified NTLDR file is detected as
Virus:DOS/Samael.
If the system year ends with "09", for example, 2009 or 1909, this worm displays the following message on the screen when the system restarts:
No matter what the user enters, after three tries, this worm displays the following message:
And user login is not continued, effectively locking the user out and rendering the system unusable.
If the system does not end with "09", the worm does not display the above messages. However, the NTLDR file is still corrupted, and the system is still unusable.
Drops Other Malware
As indicated above, Worm:Win32/Samael.A drops the file
%windir%\smss.bat, which is detected as
Worm:BAT/Samael.A, in the system. It is used to shut the system down, presumably to display the above messages when the system is restarted.
Analysis by Elda Dimakiling