Remotely Exploitable Buffer Overflow in Outlook "Malformed E-mail MIME Header" Vulnerability

  Microsoft Outlook




Remotely Exploitable Buffer Overflow in Outlook "Malformed E-mail MIME Header" Vulnerability

"the new generation of virus is here.  by sending a malformed e-mail you can run arbitrary code 
on the remote machine."

USSR Advisory Code:  USSR-2000050

Release Date:
July 19, 2000

Systems Affected:
Microsoft Outlook Express 4.0
Microsoft Outlook Express 4.01
Microsoft Outlook Express 5.0
Microsoft Outlook Express 5.01
Microsoft Outlook 97
Microsoft Outlook 98
Microsoft Outlook 2000


The Ussr Labs team has recently discovered an exploitable buffer
overflow in all versions of Outlook.

The vulnerability could enable a malicious sender of an e-mail
message with a malformed header to cause and exploit a buffer overrun
on a user's machine. The buffer overrun could crash Outlook Express, 
Outlook e-mail client, or cause arbitrary code to run on the user's

The danger in this vulnerability is that the buffer overrun would
occur even if the user does not open or preview the e-mail message.

This is because the buffer overrun occurs and the vulnerability is
triggered during the process of downloading the e-mail message from
server to client.  It is unlikely that a user will be able to delete
the malicious message from the client.

Instead, the user should request that the e-mail server administrator
delete the message from the mail server.

A nice little feature about this buffer overflow is that the mail is
not deleted from the server, and next time outlook is loaded, it will
try to download the mail, causing it to crash again.

This security vulnerability research and the exploit development made
by USSR Labs was based on a previous information supplied by a
researcher of GFI Security, known as Metatron, since it against GFI
policies to create exploits.


To test this vulnerability I telneted to an SMTP server and sent the 
following to myself:

Date: Thu,13 Jun 2000 12:33:16 +1111111111111111111111111111111111111111111111111111111111111


After the remote host closed the connection and sent mail to the appropriate 
address, upon receipt of the mail the following fault was generated by Outlook:

	OUTLOOK caused an invalid page fault in
	module  at 00de:00aedc5a.
	EAX=80004005 CS=016f EIP=00aedc5a EFLGS=00010286
	EBX=70bd4899 SS=0177 ESP=0241ef94 EBP=31313131
	ECX=00000000 DS=0177 ESI=0241efc6 FS=2b57
	EDX=81c0500c ES=0177 EDI=0241efc4 GS=0000
	Bytes at CS:EIP:
	Stack dump:
	0241f360 0241f554 00000000 00000001 00000000 004580d0 00000054 00000054 
	0241efc4 0000003b 00000100 00000017 3131312b 31313131 31313131 31313131 

SPECIAL NOTE: We take no responsibility for this code.  It is for
educational purposes only.


Malformed Email Spawner.
This code will create and send an e-mail message, that when 
downloaded by outlook, will open

Unix/Linux Perl Version:

Windows Console Version:

Windows Console Version Source:

Vendor Status:  
Informed!, Contacted!.

More Information:

Microsoft Security Bulletin MS00-045: Frequently Asked Questions,

The vulnerability can be eliminated by a default installation of
either of the following upgrades:

Internet Explorer 5.01 Service Pack 1,

Internet Explorer 5.5 on any system except Windows 2000,

Vendor   Url:
Program  Url:

Related Links:

Underground Security Systems Research:

CrunchSp Product:

Attrition, w00w00, beavuh, Rhino9,,,
ADM, HNC, #Synnergy (efnet),#hackphreak (efnet), Technotronic, dethy,
thrill, RFP and Wiretrip.

Copyright (c) 1999-2000 Underground Security Systems Research.
Permission is hereby granted for the redistribution of this alert
electronically. It is not to be edited in any way without explicit
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The information within this paper may change without notice. We may
not be held responsible for the use and/or potential effects of these
programs or advisories.  Use them and read them at your own risk or
not at all. You solely are responsible for this judgement. 

Please send suggestions, updates, and comments to:

Underground Security Systems Research