NGSSoftware Insight Security Research Advisory Name: Microsoft Internet Explorer BufferOverrun Systems Affected: All versions IE Severity: Critical Category: Indirect Remote Buffer Overrun Vendor URL: http://www.mircosoft.com Author: Mark Litchfield (markat_private) Date: 26th August 2002 Advisory number: #NISR26082002 Description *********** Microsoft® ActiveX® controls, formerly known as OLE controls or OCX controls, are components (or objects) you can insert into a Web page or other application to reuse packaged functionality someone else programmed. Whether you use an ActiveX control (formerly called an OLE control) or a Java object, Microsoft Visual Basic Scripting Edition and Microsoft Internet Explorer handle it the same way. Details ******* An unchecked buffer exists in the ActiveX control used to display specially formatted text. This could be executed by encouraging an unsuspecting user to visit a malicious web page including the below code. <OBJECT classid="clsid:99B42120-6EC7-11CF-A6C7-00AA00A47DD2" id=lblActiveLbl width=250 height=250 align=left hspace=20 vspace=0 > <PARAM NAME="Angle" VALUE="90"> <PARAM NAME="Alignment" VALUE="4"> <PARAM NAME="BackStyle" VALUE="0"> <PARAM NAME="Caption" VALUE="long char string"> <PARAM NAME="FontName" VALUE="NGS Software Font"> <PARAM NAME="FontSize" VALUE="50"> <PARAM NAME="FontBold" VALUE="1"> <PARAM NAME="FrColor" VALUE="0"> </OBJECT> By supplying an overly long value for the "Caption" parameter a saved return address stored on the stack will be overwritten allowing an attacker to gain control of Internet Explorer's path of execution. Any arbitary code would execute in the context of the logged on user. By sending the intended targer a specially crafted e-mail or by enticing them to a malicious website an attacker will be able to gain remote control of that users desktop. Fix Information *************** NGSSoftware alerted Microsoft to these problems on the 29th April 2002. NGSSoftware highly recommend installing Microsoft Patch found at http://www.microsoft.com/windows/ie/downloads/critical/q323759ie/default.asp Further Information ******************* For further information about the scope and effects of buffer overflows, please see http://www.ngssoftware.com/papers/non-stack-bo-windows.pdf http://www.ngssoftware.com/papers/ntbufferoverflow.html http://www.ngssoftware.com/papers/bufferoverflowpaper.rtf http://www.ngssoftware.com/papers/unicodebo.pdf
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