I don't normally repost security alerts but as there has been some
discussion about Outlook recently *and* the following alert (which also
applies to other flavours of MS email and Netscape) appears fairly
serious I am going to make an exception.
[ For Public Release ]
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__________________________________________________________
The U.S. Department of Energy
Computer Incident Advisory Capability
___ __ __ _ ___
/ | /_\ /
\___ __|__ / \ \___
__________________________________________________________
ADVISORY BULLETIN
Mime Name Vulnerability in Outlook and Messenger
July 27, 1998 20:00 GMT Number I-077
______________________________________________________________________________
PROBLEM: A buffer overflow vulnerability has been identified in
Microsoft Outlook, Outlook Express, and Netscape Messenger
(Mail) that allows an e-mail or news message to contain
malicious code in a mime header. That code is executed when the
header is read by the e-mail/news reader. All of these
e-mail/news readers are widely distributed with popular
packages such as Internet Explorer, Windows 98, Windows 97,
Office 97, and Netscape Communicator.
PLATFORM: Any platform that runs the vulnerable e-mail/news readers:
Windows 95, Windows 98, Windows NT, Macintosh and Solaris.
DAMAGE: If exploited, this vulnerability allows a remote user to run
arbitrary code on a users machine with the user's privileges.
The remotely executed code could do anything from sending
thousands of e-mails in the user's name to formatting the hard
drive.
SOLUTION: Apply patches from Microsoft and Netscape.
______________________________________________________________________________
VULNERABILITY Risk is high. While we have not yet heard of anyone exploiting
ASSESSMENT: this vulnerability for malicious purposes, the ease with which
it can be exploited, the wide distribution of vulnerable
readers, and the potential for damage makes it a very serious
problem.
______________________________________________________________________________
Mime Name Vulnerability in Outlook and Messenger
CIAC has received information about a vulnerability in the Microsoft and
Netscape e-mail/news products: Outlook, Outlook Express, and Messenger (Mail).
These e-mail/news programs improperly handle the mime name tags used to
identify attachments to e-mail/news messages. An improper name tag can result
in a buffer overflow condition when the program processes the attachment. As
the reader generally processes the attachments when the user reads the
message, the buffer overflow condition can be initiated, by simply reading the
e-mail/news message.
The buffer overflow condition can then be exploited to run any arbitrary code
contained in the attachment. The code runs with the user's permissions to do
anything the user can do such as re-send the e-mail to the users mailing list,
change files, or format the hard drive.
While at first glance this appears to the Good_Times hoax come to life (see
http://ciac.llnl.gov/ciac/CIACHoaxes.html#goodtimes) this is not really the
case. Good_Times was supposed to run itself on any system that downloaded and
read the Good_Times message. This mime name vulnerability is caused by
improperly handled mime headers in a few versions of some very popular e-
mail/news readers. By replacing the vulnerable readers with properly patched
versions, this vulnerability is eliminated.
BACKGROUND
==========
The Multipurpose Internet Mail Extensions or MIME is a protocol for sending
non-ASCII text or multi-part documents as part of e-mail or news message.
Users of the readers rarely see the mime headers since they are stripped out
of the message as it is downloaded onto the user's machine. The mime headers
tell the reader where the different parts of the message begin and end, what
type of data is contained in the message part, what encoding is used to
convert the message, what the name of the file is that was attached as a
message part, and other information necessary for the successful transmission
of the data.
In the vulnerable readers, the headers are read into memory without checking
their length. When the length of the header is longer than the buffer in
memory where the reader tries to store it, data in the header beyond the
length of the buffer overwrites other code and data in memory. This
overwriting is the classic "buffer overflow" condition. If the overwritten
piece of memory is part of the running program, the code from the header in
the overwritten part is executed in place of the program's code.
ASSESSMENT
==========
As of the release date of this advisory, we have not heard of anyone
exploiting this vulnerability but we believe it to be extremely serious. Users
should take immediate action to patch vulnerable systems. We base this
assessment on the ease with which the vulnerability can be exploited, the
widespread use of the vulnerable e-mail/news readers, and the potential for
doing serious damage to a computer.
An additional, serious, long-term problem is the fact that these e-mail/news
readers are automatically installed on many systems along with web browsers,
office applications and operating systems. For example, Windows 98 comes
preinstalled on many new systems and contains one of the vulnerable readers.
As the installations are usually done from a CD-ROM, reinstalling a system in
the future for any reason reinstalls the vulnerable readers. Users must insure
that if they reinstall systems that they then replace the vulnerable readers
with appropriately patched versions.
VULNERABLE APPLICATIONS
=======================
Vulnerabilities in the following applications have been confirmed by the
manufacturers:
Outlook Express v4.72.2106.4 and v4.72.3110.1
Outlook '98
Netscape Messenger (Mail) v4.05, or 4.5b1
Earlier versions of these applications are also likely to be vulnerable. The
current version of Eudora does not appear to be vulnerable. Older e-mail
readers that do not handle mime attachments are not vulnerable.
PATCHES
=======
Information is available from Microsoft at:
http://www.microsoft.com/ie/security/oelong.htm
Patched versions of Outlook and Outlook Express are available from Microsoft
at the URL:
Outlook 98
http://support.microsoft.com/support/msfe
Request the patch OLMIME from Microsoft Support
Outlook Express
First update to Internet Explorer 4.01 at:
http://www.Microsoft.com/ie
Then obtain the patch from:
http://www.microsoft.com/ie/security/oelong.htm
Patches for Macintosh and Solaris versions of Outlook Express will be
available soon at:
http://www.Microsoft.com/security
Version 4.06 of Netscape Communicator is due out around August 7 and will
contain a patched version of the e-mail reader. Patches will be available
through their Smart Update web page:
http://home.netscape.com/download/su1.html
______________________________________________________________________________
A special thanks goes to Ari Takanen and Marko Laakso of the University of
Oulu in Finland and Russ Cooper the Owner/Moderator of the NTBugtraq mailing
list for finding and verifying this vulnerability.
______________________________________________________________________________
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
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E-mail: [log in to unmask]
For emergencies and off-hour assistance, DOE, DOE contractor sites,
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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
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+1 (925) 423-3331 (28.8K baud)
CIAC has several self-subscribing mailing lists for electronic
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PLEASE NOTE: Many users outside of the DOE, ESnet, and NIH computing
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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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LAST 10 CIAC BULLETINS ISSUED (Previous bulletins available from CIAC)
I-067: AutoStart 9805 Macintosh Worm Virus
I-068: File Access Issue With Internet Information Server
I-069: Buffer overflows in some POP servers
I-070: Distributed DoS Attack Against NIS/NIS+ Networks
I-071: OpenVMS loginout Vulnerability
I-072: SunOS Solaris Vulnerabilities (libnsl, SUNWadmap)
I-073: multiscan ('mscan') Tool
I-074: Buffer Overflow in Some Implementations of IMAP Servers
I-075: Microsoft Office 98 Security Vulnerability
I-076: SGI IRIX ioconfig(1M) and disk_bandwidth(1M) Vulnerability
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--
Chris Salter (Vice Chairman) Lincolnshire Post-Polio Network
Registered Charity No. 1064177
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