TUCoPS :: Browsers :: bt45.txt

Internet Explorer Plugin.ocx heap overflow (#NISR24042003)

NGSSoftware Insight Security Research Advisory

Name:    Internet Explorer ActiveX Control Heap Overflow
Systems Affected:  IE 5.01 SP3, 5.5 SP2, 6.0 Gold, 6.0 SP1
Severity:  Critical Risk
Category:               Heap Overflow
Vendor URL:   http://www.microsoft.com
Author:   Mark Litchfield (mark@ngssoftware.com)
Date:   24th April 2003
Advisory number: #NISR24042003

Internet Explorer is the most popular web browser in use by the internet
community with a reported 95% user base of internet users. IE suffers from a
heap based buffer overflow vulnerability that can be exploited via e-mail or
by viewing a web page.

There is an exploitable heap overflow vulnerability in Microsoft's ActiveX
control, Plugin.ocx. By default, plugin.ocx is marked safe for scripting,
and as such, if an IE user were to visit a malicious web page, the overflow
could be triggered allowing for a "remote" compromise of the user's machine.
Alternatively, an attacker could send their target a specially crafted
e-mail, loaded with an exploit to take advantage of this vulnerability. The
problem arises by passing an overly long string to the Load method of the

Fix Information
NGSSoftware alerted Microsoft to this vulnerability on 13th December 2002.
The patch information is available from

Further Information
For further information about the scope and effects of buffer overflows,
please see


About NGSSoftware
NGSSoftware design, research and develop intelligent, advanced application
security assessment scanners. Based in the United Kingdom, NGSSoftware have
offices in the South of London and the East Coast of Scotland. NGSSoftware's
sister company NGSConsulting, offers best of breed security consulting
services, specialising in application, host and network security


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