[NT] Microsoft Content Management Server Remote Code Execution (MS07-018)

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Microsoft Content Management Server Remote Code Execution (MS07-018)
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SUMMARY

Remote code execution, cross-site scripting and spoofing vulnerabilities
exist in Microsoft Content Management Server (MCMS).

DETAILS

Affected Software:
* Microsoft Content Management Server 2001 Service Pack 1 -
<http://www.microsoft.com/downloads/details.aspx?FamilyId=0AAC923D-A6B8-4023-9977-AEA6782DC1C7> Download the update (KB924430)
* Microsoft Content Management Server 2002 Service Pack 2 -
<http://www.microsoft.com/downloads/details.aspx?FamilyId=41D53931-BCF8-43D9-9D16-592EBFB0AC04> Download the update (KB924429)

CMS Memory Corruption Vulnerability - CVE-2007-0938:
A remote code execution vulnerability exists in Content Management Server
because of the way that it handles a specially crafted HTTP request.

An attacker who successfully exploited this vulnerability could take
complete control of an affected system. An attacker could then install
programs; view, change, or delete data; or create new accounts with full
user rights.

Mitigating Factors for CMS Memory Corruption Vulnerability -
CVE-2007-0938:
On Microsoft Internet Information Service 6.0, the W3WP.exe worker process
by default is a low-privilege process running as the built-in Network
Service account.
Note This only applies to Content Management Server 2002.

Customers who have configured Microsoft Content Management Server (MCMS)
Web sites in their own application pools to isolate them from other Web
sites could limit the impact of an attack.

FAQ for CMS Memory Corruption Vulnerability - CVE-2007-0938:
What is the scope of the vulnerability?
A remote code execution vulnerability exists in Content Management Server
because of the way that it handles a specially crafted HTTP request. An
attacker who successfully exploited this vulnerability could remotely take
complete control of an affected system. An attacker could then install
programs; view, change, or delete data; or create new accounts with full
user rights.

What causes the vulnerability?
A remote code execution vulnerability results from the way that the
Microsoft Content Management Server handles unexpected characters in an
HTTP request.

What is Microsoft Content Management Server?
Microsoft Content Management Server (MCMS) enables customers to build,
deploy, and maintain Web sites. Using MCMS, customers can create, publish
and manage Web content, as well as managing the server resources that are
available to the site.

I am running Microsoft Content Management Server 2001 and have customized
the ManualLogin.asp file, is there anything I need to do?
This security update does not update ManualLogin.asp. Any customizations
done to this page will therefore remain after this update has been
applied. We do still recommend that customized ASP pages are backed up
before doing maintenance on any Web site.

What might an attacker use the vulnerability to do?
An attacker who successfully exploited this vulnerability could take
complete control of the affected system.

How could an attacker exploit the vulnerability?
An attacker could try to exploit the vulnerability by constructing a
specially crafted URL and sending an HTTP GET request to a CMS system.

What systems are primarily at risk from the vulnerability?
Web sites that are maintained using an affected versions of Microsoft
Content Management Server.

What does the update do?
The update removes the vulnerability by modifying the way that Content
Management Server validates an HTTP request.

When this security bulletin was issued, had this vulnerability been
publicly disclosed?
No. Microsoft received information about this vulnerability through
responsible disclosure. Microsoft had not received any information to
indicate that this vulnerability had been publicly disclosed when this
security bulletin was originally issued.

When this security bulletin was issued, had Microsoft received any reports
that this vulnerability was being exploited?
No. Microsoft had not received any information to indicate that this
vulnerability had been publicly used to attack customers and had not seen
any examples of proof of concept code published when this security
bulletin was originally issued.

Cross-site Scripting and Spoofing Vulnerability in CMS Vulnerability -
CVE-2007-0939:
A cross-site scripting and spoofing vulnerability exists in Microsoft
Content Management Server (MCMS) which could allow an attacker to convince
a user to run a malicious script. If this malicious script is run, it
would execute in the security context of the user. Attempts to exploit
this vulnerability require user interaction. This vulnerability could
allow an attacker access to any data on the affected systems that was
accessible to the individual user.

It may also be possible for an attacker to exploit this vulnerability to
modify Web browser caches and intermediate proxy server caches, and put
spoofed content in those caches.

Mitigating Factors for Cross-site Scripting and Spoofing Vulnerability in
CMS Vulnerability - CVE-2007-0939:
* The vulnerability could not be exploited automatically through e-mail.
For an attack to be successful, a user must click a Web link that is sent
in an e-mail message.
* An attack would only be successful if the user that was convinced to
click on the attacker s specially crafted URL had access to the CMS Web
server.
* An attacker who successfully exploited the cross-site scripting aspect
of this vulnerability would gain only the same permissions as the user.
* Clients who have turned on the Do not save encrypted pages to disk
advanced Internet option in Internet Explorer would not be at risk from
any attempts to put spoofed content into the client cache if they accessed
their Web site through the Secure Sockets Layer (SSL) protocol.
* Clients who use SSL-protected connections to access the affected Web
sites would not be vulnerable to attempts to put spoofed content on
intermediate proxy server caches. This is because SSL session data is
encrypted and is not cached on intermediate proxy servers.
* If spoofed content is successfully put in an intermediate proxy server
s cache, it could be difficult for an attacker to predict which users
would be served the spoofed cached content.

Workarounds for Cross-site Scripting and Spoofing Vulnerability in CMS
Vulnerability - CVE-2007-0939:
Microsoft has tested the following workaround. Although these workaround
will not correct the underlying vulnerability, they help block known
attack vectors. When a workaround reduces functionality, it is identified
in the following section.

* Setting an MCMS site to Yes-Read Only will disable content authoring
and access to that MCMS server entry point from Site Manager

Setting an MCMS site to Yes-Read Only will disable content authoring and
access to that MCMS server entry point from Site Manager, but doesn t
remove any files from the file system. If you want to use the Site Manager
tool to modify settings on a read-only MCMS site, you must first make the
site read-write in the Web Server Configuration tool.
Setting an MCMS site to read-only means that you can t use the client-side
SDAPI (or Site Manager) to deploy content. On a read-only site, you must
use the server-side SDAPI for content deployment API unless you have a
separate read-write Web entry point.

To modify the MCMS site to Yes-Read Only, follow these steps:
1. Click Start, click Programs, and then select Microsoft Content
Management Server.
2. Click Server Configuration Application.
3. Click the Web tab and then select Configure.
4. In the dialog box for the MCMS Web site you wish to configure, select
Yes Read Only.
5. Click OK to save the changes.

Impact of Workaround: Users will no longer be able to author content via
MCMS Web Author (you cannot login with edit rights on an MCMS Server) nor
via Site Manager.

FAQ for Cross-site Scripting and Spoofing Vulnerability in Microsoft
Content Management Server Vulnerability - CVE-2007-0939:
What is the scope of the vulnerability?
A cross-site scripting and spoofing vulnerability exists in Microsoft
Content Management Server (MCMS). The vulnerability could allow the
injection of a client-side script in the user's browser. In a Web-based
attack scenario a compromised Web site could accept or host user-provided
content or advertisements which could contain specially crafted content
that could exploit this vulnerability.

The script could take any action on the user's behalf that the Web site is
authorized to take. This could include monitoring the Web session and
forwarding information to a third party, running other code on the user's
system, and reading or writing cookies.

What causes the vulnerability?
The cross-site scripting (XSS) vulnerability is caused by the Microsoft
Content Management Server not completely validating input that is provided
in a HTML redirection query before it sends this input to the browser.

What is Microsoft Content Management Server?
<http://www.microsoft.com/cmserver/default.mspx> Microsoft Content
Management Server (MCMS) enables customers to build, deploy, and maintain
Web sites. Using MCMS, customers can create, publish and manage Web
content, as well as managing the server resources that are available to
the site.

What is cross-site scripting?
Cross-site scripting (XSS) is a class of security vulnerability that can
enable an attacker to "inject" script code into a user's session with a
Web site. The vulnerability can affect Web servers that dynamically
generate HTML pages. If these servers embed browser input in the dynamic
pages that they send back to the browser, these servers can be manipulated
to include maliciously supplied content in the dynamic pages. This can
allow malicious script to be executed. Web browsers may perpetuate this
problem through their assumptions of "trusted" sites and their use of
cookies to maintain persistent state with the Web sites that they
frequent. An XSS attack does not modify Web site content. Instead, it
inserts new, malicious script that can execute at the browser in the
context that is associated with a trusted server.

How does cross-site scripting work?
Web pages contain text and HTML markup. Text and HTML markup are generated
by the server and are interpreted by the client. If untrusted content is
introduced into a dynamic page, neither the server nor the client has
sufficient information to recognize that this injection has occurred and
to take protective measures.

I am running Microsoft Content Management Server 2001 and have customized
the ManualLogin.asp file, is there anything I need to do?
This security update does not update ManualLogin.asp. Any customizations
done to this page will therefore remain after this update has been
applied. We do still recommend that customized ASP pages are backed up
before doing maintenance on any Web site.

What might an attacker use the vulnerability to do?
An attacker who successfully exploited this vulnerability could inject a
client side script in the user's browser. The script could spoof content,
disclose information, or take any action that the user could take on the
affected Web site. Attempts to exploit this vulnerability would require
user interaction. It may also be possible to exploit the vulnerability to
manipulate Web browser caches and intermediate proxy server caches, and
put spoofed content in those caches.

How could an attacker exploit the vulnerability?
In an e-mail attack scenario an attacker could exploit the vulnerability
by sending a specially crafted e-mail message to a user of a server that
is running an affected software application. The attacker could then
convince the user to click a link in the e-mail message.

In a Web-based attack scenario a compromised Web an attacker could inject
a client side script in the user's browser. The script could spoof
content, disclose information, or take any action that the user could take
on the affected Web site. Attempts to exploit this vulnerability would
require user interaction.

It may also be possible to exploit the vulnerability to modify Web browser
caches and intermediate proxy server caches and to put spoofed content in
those caches.

What systems are primarily at risk from the vulnerability?
Web sites that are maintained using an affected versions of Microsoft
Content Management Server.

Could the vulnerability be exploited over the Internet?
Yes. An attacker could try to exploit this vulnerability over the
Internet. An attacker would need to know the full name of the CMS server
being targeted for an attack.

What does the update do?
The update removes the vulnerability by modifying the way that Content
Management Server validates HTTP redirection queries.

When this security bulletin was issued, had this vulnerability been
publicly disclosed?
No. Microsoft received information about this vulnerability through
responsible disclosure. Microsoft had not received any information to
indicate that this vulnerability had been publicly disclosed when this
security bulletin was originally issued. This security bulletin addresses
the privately disclosed vulnerability as well as additional issues
discovered through internal investigations.

When this security bulletin was issued, had Microsoft received any reports
that this vulnerability was being exploited?
No. Microsoft had not received any information to indicate that this
vulnerability had been publicly used to attack customers and had not seen
any examples of proof of concept code published when this security
bulletin was originally issued.


ADDITIONAL INFORMATION

The information has been provided by Microsoft Security Bulletin MS07-018.
The original article can be found at:
<http://www.microsoft.com/technet/security/bulletin/ms07-018.mspx>
http://www.microsoft.com/technet/security/bulletin/ms07-018.mspx



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