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              AUSCERT External Security Bulletin Redistribution
                             
                  ESB-1999.182 -- CIAC INFORMATION BULLETIN
                          ExploreZip (packed) Worm
                              02 December 1999

===========================================================================

The U.S. Department of Energy Computer Incident Advisory Capability has
released the following bulletin concerning a variant of the Windows 9x/NT
Trojan horse worm ExploreZip (described previously in CIAC Bulletin J-047,
redistributed as AusCERT ESB-1999.078).  The new variant is a packed
version of the original worm and is not detectable using previous
signatures for the original worm.

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             __________________________________________________________

                       The U.S. Department of Energy
                    Computer Incident Advisory Capability
                           ___  __ __    _     ___
                          /       |     /_   /
                          \___  __|__  /     \___
             __________________________________________________________

                             INFORMATION BULLETIN

                            ExploreZip (packed) Worm
                        Addition to CIAC Bulletin J-047

December 1, 1999 17:00 GMT                                        Number K-008
______________________________________________________________________________
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:windowssystemExplore.exe

    or

        run=C:windowssystem\_setup.exe

    If  your windowssystem 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_USERSoftwareMicrosoftWindows 
NTCurrentVersionWindowsRun 

    Value = Explore.exe or _setup.exe

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

______________________________________________________________________________

CIAC, the Computer Incident Advisory Capability, is the computer
security incident response team for the U.S. Department of Energy
(DOE) and the emergency backup response team for the National
Institutes of Health (NIH). CIAC is located at the Lawrence Livermore
National Laboratory in Livermore, California. CIAC is also a founding
member of FIRST, the Forum of Incident Response and Security Teams, a
global organization established to foster cooperation and coordination
among computer security teams worldwide.

CIAC services are available to DOE, DOE contractors, and the NIH. CIAC
can be contacted at:
    Voice:    +1 925-422-8193
    FAX:      +1 925-423-8002
    STU-III:  +1 925-423-2604
    E-mail:   ciac@llnl.gov

For emergencies and off-hour assistance, DOE, DOE contractor sites,
and the NIH may contact CIAC 24-hours a day. During off hours (5PM -
8AM PST), use one of the following methods to contact CIAC:

    1.  Call the CIAC voice number 925-422-8193 and leave a message, or

    2.  Call 888-449-8369 to send a Sky Page to the CIAC duty person or

    3.  Send e-mail to 4498369@skytel.com, or

    4.  Call 800-201-9288 for the CIAC Project Leader.

Previous CIAC notices, anti-virus software, and other information are
available from the CIAC Computer Security Archive.

   World Wide Web:      http://www.ciac.org/
                        (or http://ciac.llnl.gov -- they're the same machine)
   Anonymous FTP:       ftp.ciac.org
                        (or ciac.llnl.gov -- they're the same machine)
   Modem access:        +1 (925) 423-4753 (28.8K baud)
                        +1 (925) 423-3331 (28.8K baud)

CIAC has several self-subscribing mailing lists for electronic
publications:
1. CIAC-BULLETIN for Advisories, highest priority - time critical
   information and Bulletins, important computer security information;
2. SPI-ANNOUNCE for official news about Security Profile Inspector
   (SPI) software updates, new features, distribution and
   availability;
3. SPI-NOTES, for discussion of problems and solutions regarding the
   use of SPI products.

Our mailing lists are managed by a public domain software package
called Majordomo, which ignores E-mail header subject lines. To
subscribe (add yourself) to one of our mailing lists, send the
following request as the E-mail message body, substituting
ciac-bulletin, spi-announce OR spi-notes for list-name:

E-mail to       ciac-listproc@llnl.gov or majordomo@rumpole.llnl.gov:
        subscribe list-name 
  e.g., subscribe ciac-bulletin 

You will receive an acknowledgment E-mail immediately with a confirmation
that you will need to mail back to the addresses above, as per the
instructions in the E-mail.  This is a partial protection to make sure
you are really the one who asked to be signed up for the list in question.

If you include the word 'help' in the body of an E-mail to the above address,
it will also send back an information file on how to subscribe/unsubscribe,
get past issues of CIAC bulletins via E-mail, etc.

PLEASE NOTE: Many users outside of the DOE, ESnet, and NIH computing
communities receive CIAC bulletins.  If you are not part of these
communities, please contact your agency's response team to report
incidents. Your agency's team will coordinate with CIAC. The Forum of
Incident Response and Security Teams (FIRST) is a world-wide
organization. A list of FIRST member organizations and their
constituencies can be obtained via WWW at http://www.first.org/.

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
legal liability or responsibility for the accuracy, completeness, or
usefulness of any information, apparatus, product, or process
disclosed, or represents that its use would not infringe privately
owned rights. Reference herein to any specific commercial products,
process, or service by trade name, trademark, manufacturer, or
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.

LAST 10 CIAC BULLETINS ISSUED (Previous bulletins available from CIAC)

J-070: Microsoft Windows 95 and 98 Telnet Client Vulnerability
J-071: Buffer Overflow Vulnerability in amd
J-072: IBM AIX Buffer Overflow Vulnerability
K-001: Four Vulnerabilities in the Common Desktop Environment
K-002: Microsoft IE 5 Vulnerability - "download behavior"
K-003: Windows NT 4.0 does not delete Unattended Installation File
K-004: Microsoft "Excel SYLK" Vulnerability
K-005: Microsoft "Virtual Machine Verifier" Vulnerability
K-006: Microsoft - Improve TCP Initial Sequence Number Randomness
K-007: Multiple Vulnerabilities in BIND

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