K-008: ExploreZip (packed) Worm

PROBLEM:       A variant of the ExploreZip Worm (See CIAC Bulletin J-047) is
               spreading rapidly. The new variant is a packed version of the
               original worm and is not detected by existing antivirus
               programs. The worm spreads by sending itself as an attachment
               to e-mail. The worm is destructive, zeroing the contents of
               files and making them unrecoverable.
PLATFORM:      The worm runs on all Windows platforms but Outlook or Exchange
               are needed to spread.
DAMAGE:        The worm zeroes the contents of files making them unrecoverable
               by any reasonable means. The worm specifically targets .h, .c,
               .cpp, .asm, .doc, .xls, and .ppt files.
SOLUTION:      Do not execute an e-mail attachment named zipped_files.exe as
               this is the worm program. Update your antivirus software as
               soon as updates are available.
VULNERABILITY  Risk is high: This worm spreads rapidly using your e-mail
ASSESSMENT:    program to send itself to everyone in your e-mail inbox.


CIAC has information that the ExploreZip (packed) Worm is spreading rapidly.

The ExploreZip (packed) Worm is a variant of the ExploreZip worm described in
CIAC bulletin J-047. This variant is only different from the original in that
it is a packed executable. Packed executables are a form of file compression
that is uncompressed on the fly when the program is executed. See the CIAC
bulletin J-047 for the details of this worm.

The worm spreads as an attachment to an e-mail message that appears to be a
reply to a message you have sent. The attachment is named zipped_files.exe and
is supposed to be a self extracting archive of documents. When the attachment
is run, it checks your e-mail inbox and sends a reply to every message it
finds there. In the reply, it adds the text:

     Hi !
     I received your email and I shall send you a reply ASAP.
     Till then, take a look at the attached zipped docs.
     bye.

and attaches the worm program. After sending the e-mail messages with the
attached worm to all your associates, the worm starts zeroing the contents of
files with the following file extensions.

       .h .c. cpp .asm .doc .xls .ppt

Because this is a packed version of the original worm, current versions of
most antivirus products do not detect it. Updates are already available or are
expected momentarily.

If you have been infected and need to remove this worm by hand, perform these
steps:

    1. For Windows 95, 98, open the WIN.INI file and remove the following
line:

        run=C:\windows\system\Explore.exe

    or

        run=C:\windows\system\_setup.exe

    If  your windows\system directory is in a different location, then
    the strings above will also be different.

    For Windows NT, run REGEDIT and remove the following entry:

        HKEY_CURRENT_USER\Software\Microsoft\Windows
NT\CurrentVersion\Windows\Run

    Value = Explore.exe or _setup.exe

    2. Delete the file C:\windows\system\Explore.exe or
C:\windows\system\_setup.exe. Again, if your windows\system directory is in a
different location, use that path instead of the two listed above.




CIAC services are available to DOE, DOE Contractors, and the NIH. CIAC
can be contacted at:
    Voice:          +1 925-422-8193 (7 x 24)
    FAX:            +1 925-423-8002
    STU-III:        +1 925-423-2604
    E-mail:          ciac@llnl.gov
    World Wide Web:  http://www.ciac.org/
                     http://ciac.llnl.gov
                     (same machine -- either one will work)
    Anonymous FTP:   ftp.ciac.org
                     ciac.llnl.gov
                     (same machine -- either one will work)




This document was prepared as an account of work sponsored by an
agency of the United States Government. Neither the United States
Government nor the University of California nor any of their
employees, makes any warranty, express or implied, or assumes any
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otherwise, does not necessarily constitute or imply its endorsement,
recommendation or favoring by the United States Government or the
University of California. The views and opinions of authors expressed
herein do not necessarily state or reflect those of the United States
Government or the University of California, and shall not be used for
advertising or product endorsement purposes.


UCRL-MI-119788 

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