This worm arrives as an email with one of several attachment names and a combination of two appended extensions. It contains a set of bits that control its behavior:
001 Log every window text
002 Encrypt keylog
004 Send log file to one of its addresses
008 Send cached passwords
010 Shut down at specified time
020 Use copyname as registry name (else kernel32)
040 Use kernel32.exe as copyname
080 Use current filename as copypath (skips 100 check)
100 Copy to %system% (else copy to %windows%)
: If Norton AntiVirus detects this in an email message as W32.Badtrans@mm.enc (not as W32.Badtrans.B@mm), this is the detection for the MIME-encoded exploit in the body of the email, and it is harmless as long as the attachment has been deleted. We recommend that you delete messages detected as W32.Badtrans.B@mm.enc and notify the person who sent it to you. We also strongly recommend that you run a full system scan to make sure that no other infection exists.
For additional information on .enc detections, read the document What is an .enc detection?
When it is first executed, it copies itself to %System% or %Windows% as Kernel32.exe, based on the control bits. Then it registers itself as a service process (Windows 9x/Me only). It creates the key log file %System%\Cp_25389.nls and drops %System%\Kdll.dll which contains the key logging code.
%Windows% and %System% are variables. The worm locates the \Windows folder (by default this is C:\Windows or C:\Winnt) or the \System folder (by default this is C:\Windows\System or C:\Winnt\System32) and copies itself to that location.
A timer is used to examine the currently open window once per second and to check for a window title that contains any of the following as the first three characters:
These texts form the start of the words LOGon, PASsword, REMote, CONnection, TERminal, NETwork. There are also Russian versions of these same words in the list. If any of these words are found, then the key logging is enabled for 60 seconds. Every 30 seconds, the log file and the cached passwords are sent to one of these addresses or some others which are currently not operational:
After 20 seconds, the worm shuts down if the appropriate control bit is set.
If RAS support is present on the computer, then the worm waits for an active RAS connection. When such a connection is made, with a 33-percent chance, the worm searches for email addresses in *.ht* and *.asp in %Personal% and Internet Explorer %Cache%. If it finds addresses in these files, then it sends mail to those addresses using the victim's SMTP server. If this server is unavailable, the worm will choose from a list of its own. The attachment name will be one of the following:
In all cases, MAPI will also be used to find unread mail to which the worm will reply. The subject will be "Re:". In that case, the attachment name will be one of the following:
In all cases, the worm appends two extensions. The first is one of the following:
The second extension that is appended to the file name is one of the following:
The resulting file name would look similar to CARD.doc.pif or NEWS_DOC.mp3.scr.
If SMTP information can be found on the computer, then it will be used for the From:
field. Otherwise, the From:
field will be one of these:
- "Mary L. Adams" <firstname.lastname@example.org>
- "Monika Prado" <email@example.com>
- "Support" <firstname.lastname@example.org>
- " Admin" <email@example.com>
- " Administrator" <firstname.lastname@example.org>
- "JESSICA BENAVIDES" <email@example.com>
- "Joanna" <firstname.lastname@example.org>
- "Mon S" <email@example.com>
- "Linda" <firstname.lastname@example.org>
- " Andy" <email@example.com>
- "Kelly Andersen" <Gravity49@aol.com>
- "Tina" <firstname.lastname@example.org>
- "Rita Tulliani" <email@example.com>
- "JUDY" <JUJUB271@AOL.COM>
- " Anna" <firstname.lastname@example.org>
Email messages use the malformed MIME exploit to allow the attachment to execute in Microsoft Outlook without prompting. For information on this, go to:
The worm writes email addresses to the %System%\Protocol.dll file to prevent multiple emails to the same person. Additionally, the underscore ( _ ) character is prepended to the sender's email address, which prevents replying to infected mails to warn the sender (for example, email@example.com becomes firstname.lastname@example.org).
After sending the mail, the worm adds the value
to the registry key
This causes the worm to run the next time that you start Windows. This value can differ based on the control bits mentioned previously.
Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":