Microsoft Security Bulletin MS07-003 Vulnerabilities in Microsoft Outlook Could Allow Remote Code Execution (925938)

Microsoft Security Bulletin MS07-003
Vulnerabilities in Microsoft Outlook Could Allow Remote Code Execution (925938)
Published: January 9, 2007

Version: 1.0
Summary

Who Should Read this Document: Customers who use Microsoft Outlook

Impact of Vulnerability: Remote Code Execution

Maximum Severity Rating: Critical

Recommendation: Customers should apply the update immediately

Security Update Replacement: This bulletin replaces a prior security update. See the frequently asked questions (FAQ) section of this bulletin for the complete list.

Caveats: Microsoft Knowledge Base Article 925938 documents the currently known issues that customers may experience when they install this security update. The article also documents recommended solutions for these issues. For more information, see Microsoft Knowledge Base Article 925938.

Tested Software and Security Update Download Locations:

Affected Software:
•

Microsoft Office 2000 Service Pack 3
•

Microsoft Outlook 2000 — Download the update (KB921593)
•

Microsoft Office XP Service Pack 3
•

Microsoft Outlook 2002 — Download the update (KB921594)
•

Microsoft Office 2003 Service Pack 2
•

Microsoft Outlook 2003 — Download the update (KB924085)

Non-Affected Software:
•

Microsoft Office 2007
•

Microsoft Office Outlook 2007

The software in this list has been tested to determine whether the versions are affected. Other versions either no longer include security update support or may not be affected. To determine the support life cycle for your product and version, visit the Microsoft Support Lifecycle Web site.
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General Information

Executive Summary

Executive Summary:

This update addresses several newly discovered, privately and publicly reported vulnerabilities. The vulnerabilities are documented in the “Vulnerability Details” section of this bulletin.

When using vulnerable versions of Office, if a user is logged on with administrative user rights, an attacker who successfully exploited these vulnerabilities could take complete control of the system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.

We recommend that customers apply the update immediately.

Severity Ratings and Vulnerability Identifiers:
Vulnerability Identifiers Impact of Vulnerability Microsoft Outlook 2000 Microsoft Outlook 2002 Microsoft Outlook 2003

Microsoft Outlook VEVENT Vulnerability – CVE-2007-0033

Remote Code Execution

None

Important

Important

Microsoft Outlook Denial of Service Vulnerability – CVE-2006-1305

Denial of Service

Moderate

Moderate

Moderate

Microsoft Outlook Advanced Find Vulnerability - CVE-2007-0034

Remote Code Execution

Critical

Important

Important

Aggregate Severity of All Vulnerabilities

Critical

Important

Important

This assessment is based on the types of systems that are affected by the vulnerability, their typical deployment patterns, and the effect that exploiting the vulnerability would have on them.
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Frequently Asked Questions (FAQ) Related to This Security Update

What are the known issues that customers may experience when they install this security update?
Microsoft Knowledge Base Article 925938 documents the currently known issues that customers may experience when they install this security update. The article also documents recommended solutions for these issues. For more information, see Microsoft Knowledge Base Article 925938.
•

Microsoft Knowledge Base Article 925542 : Cannot open or save "Office Saved Searches (.oss)" files in Outlook after installing a security update that is dated January 9, 2007 (925542).

What updates does this release replace?
This security update replaces a prior security update. The security bulletin ID and affected operating systems are listed in the following table.
Bulletin ID Microsoft Outlook 2000 Microsoft Outlook 2002 Microsoft Outlook 2003

MS06-003

Not Applicable

Not Applicable

Replaced

Can I use the Microsoft Baseline Security Analyzer (MBSA) to determine whether this update is required?
The following table provides the MBSA detection summary for this security update.
Software MBSA 1.2.1 MBSA 2.0

Microsoft Outlook 2000

Yes

No

Microsoft Outlook 2002

Yes

Yes

Microsoft Outlook 2003

Yes

Yes

Note MBSA 1.2.1 uses an integrated version of the Office Detection Tool (ODT) which does not support remote scans of this security update. For more information about MBSA, visit the MBSA Web site.

For more information about the programs that Microsoft Update and MBSA 2.0 currently do not detect, see Microsoft Knowledge Base Article 895660.

For more detailed information, see Microsoft Knowledge Base Article 910723.

Can I use Systems Management Server (SMS) to determine whether this update is required?
The following table provides the SMS detection summary for this security update.
Software SMS 2.0 SMS 2003

Microsoft Outlook 2000

Yes

Yes

Microsoft Outlook 2002

Yes

Yes

Microsoft Outlook 2003

Yes

Yes

SMS uses MBSA for detection. Therefore, SMS has the same limitation that is listed earlier in this bulletin related to programs that MBSA does not detect.

For SMS 2.0, the SMS SUS Feature Pack, which includes the Security Update Inventory Tool, can be used by SMS to detect security updates. SMS SUIT uses the MBSA 1.2.1 engine for detection. For more information about the Security Update Inventory Tool, visit the following Microsoft Web site. For more information about the limitations of the Security Update Inventory Tool, see Microsoft Knowledge Base Article 306460. The SMS SUS Feature Pack also includes the Microsoft Office Inventory Tool to detect required updates for Microsoft Office applications.

For SMS 2003, the SMS 2003 Inventory Tool for Microsoft Updates can be used by SMS to detect security updates that are offered by Microsoft Update and that are supported by Windows Server Update Services. For more information about the SMS 2003 Inventory Tool for Microsoft Updates, visit the following Microsoft Web site. SMS 2003 can also use the Microsoft Office Inventory Tool to detect required updates for Microsoft Office applications.

For more information about SMS, visit the SMS Web site.

For more detailed information, see Microsoft Knowledge Base Article 910723.
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Vulnerability Details

Microsoft Outlook VEVENT Vulnerability - CVE-2007-0033

A remote code execution vulnerability exists in Microsoft Outlook. An attacker could exploit this vulnerability when Outlook parses a file and processes a malformed VEVENT record.

If a user is logged on with administrative user rights, 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. Users whose accounts are configured to have fewer user rights on the system could be less affected than users who operate with administrative user rights.

Mitigating Factors for Microsoft Outlook VEVENT Vulnerability - CVE-2007-0033:
•

An attacker who successfully exploited this vulnerability could gain the same user rights as the local user. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.
•

MAPI is not a valid attack vector for this issue due to Exchange's handling of iCal calendar data embedded in messages or in .ICS attachments.
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Workarounds for Microsoft Outlook VEVENT Vulnerability - CVE-2007-0033:

Microsoft has tested the following workarounds. Although these workarounds will not correct the underlying vulnerability, they help block known attack vectors. When a workaround reduces functionality, it is identified in the following section.
•

Modify the Access Control List on the “MapiCvt Class”registry key.
Modifying the Access Control List on the MapiCvt Class registry key helps protect the affected system from attempts to exploit this vulnerability. To modify the MapiCvt Class registry key, follow these steps.

Note Using Registry Editor incorrectly can cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk. For information about how to edit the registry, view the "Changing Keys And Values" Help topic in Registry Editor (Regedit.exe) or view the "Add and Delete Information in the Registry" and "Edit Registry Data" Help topics in Regedt32.exe.

Note We recommend backing up the registry before you edit it.

For Windows 2000

Click Start, click Run, type "regedt32" (without the quotation marks), and then click OK.

Expand HKEY_CLASSES_ROOT, expand CLSID, and then click {0006F085-0000-0000-C000-000000000046}.

Click Security, and then click Permissions.

Note Make a note of the permissions that are listed in this dialog box so that you can restore them to their original values at a later time.

Click to clear the Allow Inheritable Permissions from the parent to propagate to this object check box. You are prompted to click Copy, Remove, or Cancel. Click Remove, and then click OK.

You receive a message that states that no one will be able to access this registry key. Click Yes when you are prompted to do so.

For Windows XP Service Pack 2

Click Start, click Run, type "regedit" (without the quotation marks), and then click OK.

Expand HKEY_CLASSES_ROOT, expand CLSID, and then click {0006F085-0000-0000-C000-000000000046}.

Click Edit, and then click Permissions.

Note Make a note of the permissions that are listed in this dialog box so that you can restore them to their original values at a later time

Click Advanced.

Click to clear the Inherit from parent the permission entries that apply to child objects. Include these with entries explicitly defined here check box. You are prompted to click Copy, Remove, or Cancel. Click Remove, and then check OK.

You receive a message that states that no one will be able to access this registry key. Click Yes, and then click OK to close the Permissions for {0006F085-0000-0000-C000-000000000046} dialog box.
•

Back up and remove the MIMEDIR.DLL {0006F085-0000-0000-C000-000000000046} “MapiCvt Class” registry key.
Removing the MIMEDIR.DLL {0006F085-0000-0000-C000-000000000046} “MapiCvt Class” registry key helps protect the affected system from attempts to exploit this vulnerability. To backup and remove the MIMEDIR.DLL {0006F085-0000-0000-C000-000000000046} “MapiCvt Class” registry key, follow these steps:

Note Using Registry Editor incorrectly can cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk. For information about how to edit the registry, view the "Changing Keys And Values" Help topic in Registry Editor (Regedit.exe) or view the "Add and Delete Information in the Registry" and "Edit Registry Data" Help topics in Regedt32.exe.

Note We recommend backing up the registry before you edit it.

Click Start, click Run, type “regedit" (without the quotation marks), and then click OK.

Expand HKEY_CLASSES_ROOT, expand CLSID, and then click {0006F085-0000-0000-C000-000000000046}.

Click File, and then click Export.

In the Export Registry File dialog box, type a file name in the File Name box, and then click Save.

Click Edit, and then click Delete to remove the registry key.

In the Confirm Key Delete dialog box, you receive a “Are you sure you want to delete this key and all of its subkeys” message. Click Yes.

Command Line Instructions
To back up and delete this registry key by using a command-line command, follow these steps:

reg.exe export "HKEY_CLASSES_ROOT\CLSID\{0006F085-0000-0000-C000-000000000046}" c:\MapiCvt_Class.reg

reg.exe delete "HKEY_CLASSES_ROOT\CLSID\{0006F085-0000-0000-C000-000000000046}" c:\MapiCvt_Class.reg

Impact of Workaround: Users will be unable to use the 'Send Update' feature to send updates to existing meetings from their calendar. Users will be able to create new meetings in their calendar but will be unable to use the 'Send' feature from the meeting invite to automatically send the meeting invite to other recipients. The meeting will be saved to the calendar but the invite will stay in the 'Outbox' folder. Users will be unable to forward meetings from the calendar as iCalendar requests.
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FAQ for Microsoft Outlook VEVENT Vulnerability - CVE-2007-0033:

What is the scope of the vulnerability?
A remote code execution vulnerability exists in Microsoft Outlook. An attacker could exploit this vulnerability when Outlook parses a file and processes a malformed VEVENT record.

If a user is logged on with administrative user rights, 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. Users whose accounts are configured to have fewer user rights on the system could be less affected than users who operate with administrative user rights.

What causes the vulnerability?
Outlook does not perform sufficient data validation when processing the contents of an .iCal meeting request. When Outlook opens a specially crafted .iCal meeting request and parses a malformed VEVENT request, it may corrupt system memory in such a way that an attacker could execute arbitrary code.

What is an .iCal meeting request?
An iCal is used to create a meeting request to a recipient over the Internet, or outside the organization.

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 creating a specially crafted .ICS (iCal) file or embed the contents of an iCal calendar request in the body of a specially crafted e-mail and send it to a user of Outlook who connects to a POP, IMAP or HTTP server to retrieve their e-mail.

What systems are primarily at risk from the vulnerability?
Workstations and terminal servers are primarily at risk. Servers could be at more risk if administrators allow users to log on to servers and to run programs. However, best practices strongly discourage allowing this.

Could the vulnerability be exploited over the Internet?
Yes. An attacker could try to exploit this vulnerability over the Internet. Firewall best practices and standard default firewall configurations can help protect against attacks that originate from the Internet. Microsoft has provided information about how you can help protect your PC. End users can visit the Protect Your PC Web site. IT professionals can visit the Security Guidance Center Web site.

What does the update do?
The update removes the vulnerability by modifying the way that Outlook validates the length of an .iCal meeting request before it passes the message to the allocated buffer.

When this security bulletin was issued, had this vulnerability been publicly disclosed?
No. Microsoft received information about this vulnerability through responsible disclosure.

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.
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Microsoft Outlook Denial of Service Vulnerability – CVE-2006-1305

A denial of service vulnerability exists in Outlook in its processing of e-mail header information. An attacker who successfully exploited the vulnerability could send a malformed e-mail to a user of Outlook that would cause the Outlook client to fail under certain circumstances. The Outlook client would continue to fail so long as the malformed e-mail message remained on the e-mail server. The e-mail message could be deleted by an e-mail administrator, or by the user via another e-mail client such as Outlook Web Access or Outlook Express, after which point the Outlook client would again function normally.

Mitigating Factors for Microsoft Outlook Denial of Service Vulnerability - CVE-2006-1305:
•

The vulnerability is a denial of service vulnerability only. The attacker would not be able to access the user's e-mail or system in any way. The vulnerability could not be used to read, delete, create, or alter the user's e-mail.
•

If an attacker was able to send a malformed e-mail that successfully exploited this vulnerability, the malformed e-mail could be deleted either by an e-mail administrator, or by the user via another e-mail client such as Outlook Web Access or Outlook Express. Once the specially malformed e-mail has been removed, normal operation would resume.
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Workarounds for Microsoft Outlook Denial of Service Vulnerability - CVE-2006-1305:

We have not identified any workarounds for this vulnerability.
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FAQ for Microsoft Outlook Denial of Service Vulnerability - CVE-2006-1305:

What is the scope of the vulnerability?
This is a denial of service vulnerability. An attacker who exploited this vulnerability could cause the affected system to stop responding. During that time, the server cannot respond to requests.

What causes the vulnerability?
The vulnerability results because of the way Outlook processes e-mail header information.

What might an attacker use the vulnerability to do?
Any anonymous user who could deliver a specially crafted message to the affected system could try to exploit this vulnerability.

Who could exploit the vulnerability?
On Outlook, any anonymous user who could deliver a specially crafted message to the affected system could try to exploit this vulnerability.

How could an attacker exploit the vulnerability?
An attacker could try to exploit the vulnerability by creating a specially crafted message and sending the message to an affected system. The message could then cause Outlook to fail.

What systems are primarily at risk from the vulnerability?
Workstations and terminal servers are primarily at risk. Servers could be at more risk if administrators allow users to log on to servers and to run programs. However, best practices strongly discourage allowing this.

What does the update do?
The update removes the vulnerability by modifying the way that Outlook validates the length of the header in the message.

When this security bulletin was issued, had this vulnerability been publicly disclosed?
Yes. This vulnerability has been publicly disclosed. It has been assigned Common Vulnerability and Exposure number CVE-2006-1305.

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.
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Microsoft Outlook Advanced Find Vulnerability - CVE-2007-0034

A remote code execution vulnerability exists in Microsoft Outlook. An attacker could exploit this vulnerability when Outlook parses an .oss file.

If a user is logged on with administrative user rights, 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. Users whose accounts are configured to have fewer user rights on the system could be less affected than users who operate with administrative user rights.

Mitigating Factors for Microsoft Outlook Advanced Find Vulnerability - CVE-2007-0034:
•

An attacker who successfully exploited this vulnerability could gain the same user rights as the local user. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.
•

In a Web-based attack scenario, an attacker would have to host a Web site that contains an Office Saved Searches (.oss) file that is used to attempt to exploit this vulnerability. In addition, compromised Web sites and Web sites that accept or host user-provided content could contain specially crafted content that could exploit this vulnerability. An attacker would have no way to force users to visit a malicious Web site. Instead, an attacker would have to persuade them to visit the Web site, typically by getting them to click a link that takes them to the attacker's site.
•

The vulnerability cannot be exploited automatically through e-mail. For an attack to be successful, a user must open an attachment that is sent in an e-mail message.
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Workarounds for Microsoft Outlook Advanced Find Vulnerability - CVE-2007-0034:
•

Do not open or save Office Saved Searches (.oss) files that you receive from untrusted sources or that you receive unexpectedly from trusted sources. This vulnerability could be exploited when a user opens a specially crafted file.
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FAQ for Microsoft Outlook Advanced Find Vulnerability - CVE-2007-0034:

What is the scope of the vulnerability?
A remote code execution vulnerability exists in Microsoft Outlook. An attacker could exploit this vulnerability when Outlook parses an Office Saved Searches (.oss) file.

If a user were logged on with administrative user rights, 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. Users whose accounts are configured to have fewer user rights on the system could be less affected than users who operate with administrative user rights.

What causes the vulnerability?
Outlook does not perform sufficient data validation when processing the contents of .oss file. When Outlook opens a specially crafted .oss and parses the request, it may corrupt system memory in such a way that an attacker could execute arbitrary code.

What is an Office Saved Searches (.oss) File?
Saved Searches are virtual folders that contain views of e-mail items that satisfy specific search criteria. The specific search criteria are stored in .oss file.

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 creating a specially crafted .oss file in a specially crafted e-mail and send it to a user of Outlook who connects to a POP, IMAP or HTTP server to retrieve their e-mail.

What systems are primarily at risk from the vulnerability?
Workstations and terminal servers are primarily at risk. Servers could be at more risk if administrators allow users to log on to servers and to run programs. However, best practices strongly discourage allowing this.

Could the vulnerability be exploited over the Internet?
Yes. An attacker could try to exploit this vulnerability over the Internet. Firewall best practices and standard default firewall configurations can help protect against attacks that originate from the Internet. Microsoft has provided information about how you can help protect your PC. End users can visit the Protect Your PC Web site. IT professionals can visit the Security Guidance Center Web site.

What does the update do?
The update removes the ability to save these searches as well as removing the ability to open these searches.

Does this update contain any changes to functionality?
Yes. After the update for Outlook 2000, Outlook 2002, or Outlook 2003 is installed, users will not be able to save these searches as well as the ability to open these Searches. For more information, see Cannot open or save Office Saved Searches files in Outlook (KB925542).

When this security bulletin was issued, had this vulnerability been publicly disclosed?
No. Microsoft received information about this vulnerability through responsible disclosure.

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.

Acknowledgments

Microsoft thanks the following for working with us to help protect customers:
•

Lurene Grenier of Sourcefire for reporting the Microsoft Outlook VEVENT Vulnerability – CVE-2007-0033.
•

Stuart Pearson of Computer Terrorism for reporting the Microsoft Outlook Advanced Find Vulnerability - CVE-2007-0034.

Disclaimer:

The information provided in the Microsoft Knowledge Base is provided "as is" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply.

Revisions:

V1.0 (January 9, 2007): Bulletin published.