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TUCoPS :: Hacking Techniques :: ciaci085.txt

MSIE Upgrade Trojan Horse Program



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

                             INFORMATION BULLETIN

                   Microsoft IE Upgrade Trojan Horse Program

August 14, 1998 18:00 GMT                                         Number I-085
PROBLEM:       An e-mail message with an attachment claiming to be a software
               update for Internet Explorer from Microsoft Technical Support 
               actually contains a Trojan Horse program. This Trojaned 
               attachment, if executed, sends out Spam e-mail to several 
               locations on the Internet.
PLATFORM:      Windows 95/98 and Windows NT. 
DAMAGE:        No physical damage or lost data. Damage to reputation due to 
               Spam mail sent from users machine and clogged e-mail servers.
SOLUTION:      Do not execute attachments in e-mail messages from unknown 
               sources that are either unsolicited and/or not digitally 
               signed. To remove the Trojan after it has run, delete the 
               Trojaned file, shell32.exe, from the %system root% directory 
               and remove the reference to shell32.exe from the Window's 
               registry key.
VULNERABILITY  Medium. Several reports have been sent to CIAC of the
ASSESSMENT:    existence of this Trojan Horse circulating the Internet thus it 
               is in the wild.


CIAC has received information that an e-mail message is being circulated on
the Internet that professes to be from Microsoft technical support. This
message, which isn't from Microsoft technical support, claims to be a
security update for Microsoft Internet Explorer. The message contains an
attachment typically named ie080898.exe, however variations of the file name
have been reported. The attachment is actually a Trojan Horse program
targeted at Microsoft Windows 95, 98, and NT, which sends Spam e-mail
messages to several locations on the Internet. For a more detailed
explanation on Spam refer to CIAC Bulletin I-005C at:

The message looks something like the following:

Subject: FREE! Your upgrade for Microsoft Internet Explorer

As user of Microsoft Internet Explorer Microsoft Corporation provide you an
upgrade for your Microsoft Internet Explorer. Please run Ie080898.exe to
install the upgrade. This file will fix some serious bugs in your Internet

When the user restarts the computer with the Trojaned program installed an
Internet connection is made to multiple remote locations and Spam e-mail is
sent. This e-mail Spamming continues until the computer is shutdown.

The recipient address is randomly selected from the following list:

Windows 95/98 and Windows NT:
When the e-mail attachment is executed it installs shell32.exe into the
Windows %system root% directory (usually c:\winnt for Windows NT and
c:\windows for Windows 95/98) and adds a reference to that program to the
following Window's registry key
The modification causes the Trojaned shell32.exe to execute each time the
machine is restarted.


CIAC highly recommends if you receive this e-mail message do not execute the
attachment. Turn the message over to your local computer security officer
for appropriate handling. There are several clues that this e-mail message
is not a legitimate message from Microsoft Corporation. Microsoft has stated
they never send program updates by e-mail attachments to their users.
Although the e-mail message sounds technically correct, it is poorly written
and uses improper grammar. For more information on how to spot e-mail
hoaxes, see CIAC's hoax web page at:

If the Trojan program was run, you can remove the added files by taking the
following steps.

Warning: "Using Registry Editor incorrectly can cause serious, system wide
problems that may require you to reinstall Windows 95/98, or Windows NT to
correct them. Microsoft cannot guarantee that any problems resulting from
the use of Registry Editor can be solved. Use this tool at your own risk."
[Microsoft Corp.]

Windows 95/98:
Reboot the infected computer into DOS mode and delete shell32.exe located in
the Window's 95/98 %system root% directory. This step stops the unwanted
Spam e-mail from being sent out from the machine. The reference to
shell32.exe should be removed from the Window's registry from the Window's
registry key
however this is not absolutely necessary. It is important that when looking
for and removing the shell32.exe file you don't mistake this file for

Windows NT
Delete shell32.exe located in the Window's NT %system root% directory. This
will stop the unwanted Spam e-mail from being sent out from the machine. The
reference to shell32.exe should be removed from the Window's NT registry key
however this is not absolutely necessary. It is important that when looking
for and removing the shell32.exe file you don't mistake this file for

As a broader way to address this class of problems, users should always take 
care when opening attachments sent in e-mail (specially that are either 
unsolicited and/or not digitally signed).  Ie., today it is this e-mail, 
tomorrow it may be some other person, spoofing some other corporation or 
government entity.


CIAC wishes to acknowledge the contributions of Microsoft Corp. for the 
information contained in this bulletin.

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

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), call the CIAC voice number 925-422-8193 and leave a message,
or call 800-759-7243 (800-SKY-PAGE) to send a Sky Page. CIAC has two
Sky Page PIN numbers, the primary PIN number, 8550070, is for the CIAC
duty person, and the secondary PIN number, 8550074 is 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:
                        (or -- they're the same machine)
   Anonymous FTP:
                        (or -- 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
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
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 or
        subscribe list-name 
  e.g., subscribe ciac-bulletin 

You will receive an acknowledgment email immediately with a confirmation
that you will need to mail back to the addresses above, as per the
instructions in the email.  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 email to the above address,
it will also send back an information file on how to subscribe/unsubscribe,
get past issues of CIAC bulletins via email, 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

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)

I-075: Microsoft Office 98 Security Vulnerability
I-076: SGI IRIX ioconfig(1M) and disk_bandwidth(1M) Vulnerability
I-077: Mime Name Vulnerability in Outlook and Messenger
I-078: HP-UX ftp Security Vulnerability
I-079: IBM AIX "sdrd" daemon Vulnerability
I-080: Microsoft Exchange  Denial of Service Attacks
I-081: HP-UX & MPEix Predictive Vulnerability
I-082: HP-UX Netscape Servers Vulnerability
I-083: Eudora Pro E-Mail Attachment Vulnerability
I-084: Cisco IOS Remote Router Crash

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