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Re: iDefense COMRaider 'DeleteFile()' Method Arbitrary File Deletion Vulnerability


From: Jeremy Brown <0xjbrown41 () gmail com>
Date: Wed, 4 Mar 2009 17:27:05 -0500

That is actually decently accurate. Only thing is that these controls
should always (unless in a specific environment) have checks that
won't allow malicious events to occur. Even if controls aren't marked
as safe for automatic loading and execution, massive social
engineering can make them work still.

Such example would work like so...

A remote code execution exploit is found in non-safe popular
anti-virus component. Attacker sets up a website called
www.freexxxxxantivirusscan.com, convinces user to allow
loading/execution of component. Game over.

On Wed, Mar 4, 2009 at 4:42 PM, iDefense Labs
<labs-no-reply () idefense com> wrote:
Amir, et al,

We would not classify this issue as a security vulnerability.  The COM
object in question is *NOT* loadable in Internet Explorer in a default
configuration.

CLSID: {9A077D0D-B4A6-4EC0-B6CF-98526DF589E4}
 ProgId: vbDevKit.CVariantFileSystem
 Path to binary: C:\WINDOWS\vbDevKit.dll
 Doesn't implement IObjectSafety
 Registry settings:
   Registry: is not safe for initialization
   Registry: is not safe for scripting
   Killbit is NOT set

In order to load this control, the particular security setting that
would need to be modified is "Initialize and script ActiveX controls not
marked as safe for scripting".  Changing this particular setting to
"Enable", or even "Prompt", significantly impacts the browser's overall
security posture.

In short, if your machine allows this control to be loaded, then your
browser will load controls regardless of safety designations such as
"Safe for Scripting", "Safe for Initialization", and "IObjectSaftey".
This includes the ability to load controls such as WScript, which can
execute arbitrary commands out of the box.

iDefense Labs


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Charter: http://lists.grok.org.uk/full-disclosure-charter.html
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