[NT] Microsoft Outlook Code Execution (MS07-003)

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Microsoft Outlook Code Execution (MS07-003)
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SUMMARY

This update addresses several newly discovered, privately and publicly
reported vulnerabilities. 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.

DETAILS

Affected Software:
* Microsoft Office 2000 Service Pack 3
* Microsoft Outlook 2000 Download the update (
<http://www.microsoft.com/downloads/details.aspx?FamilyId=97CE0B32-C6AF-4C6C-ABF1-838ED89062EB> KB921593)
* Microsoft Office XP Service Pack 3
* Microsoft Outlook 2002 Download the update (
<http://www.microsoft.com/downloads/details.aspx?FamilyId=1D1991C5-3DE3-4258-9120-058FFD62B4F5> KB921594)
* Microsoft Office 2003 Service Pack 2
* Microsoft Outlook 2003 Download the update (
<http://www.microsoft.com/downloads/details.aspx?FamilyId=9E4DD8AE-2564-4176-AC2E-E3760058CB56> KB924085)

Non-Affected Software:
* Microsoft Office 2007
* Microsoft Office Outlook 2007

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.

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
1. Click Start, click Run, type "regedt32" (without the quotation marks),
and then click OK.
2. Expand HKEY_CLASSES_ROOT, expand CLSID, and then click
{0006F085-0000-0000-C000-000000000046}.
3. 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.

1. 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.
2. 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
1. Click Start, click Run, type "regedit" (without the quotation marks),
and then click OK.
2. Expand HKEY_CLASSES_ROOT, expand CLSID, and then click
{0006F085-0000-0000-C000-000000000046}.
3. 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

1. Click Advanced.
2. 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.
3. 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.

1. Click Start, click Run, type regedit" (without the quotation marks),
and then click OK.
2. Expand HKEY_CLASSES_ROOT, expand CLSID, and then click
{0006F085-0000-0000-C000-000000000046}.
3. Click File, and then click Export.
4. In the Export Registry File dialog box, type a file name in the File
Name box, and then click Save.
5. Click Edit, and then click Delete to remove the registry key.
6. 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:
1. reg.exe export
"HKEY_CLASSES_ROOT\CLSID\{0006F085-0000-0000-C000-000000000046}"
c:\MapiCvt_Class.reg
2. 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.

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.

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.

Workarounds for Microsoft Outlook Denial of Service Vulnerability -
CVE-2006-1305:
There are no known workarounds for this vulnerability.

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.

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.

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.

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
<http://go.microsoft.com/fwlink/?LinkId=21169> Protect Your PC Web site.
IT professionals can visit the
<http://go.microsoft.com/fwlink/?LinkId=21171> 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
<http://support.microsoft.com/kb/925542> 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.


ADDITIONAL INFORMATION

The information has been provided by Microsoft Security Bulletin MS07-003.
The original article can be found at:
<http://www.microsoft.com/technet/security/bulletin/ms07-003.mspx>
http://www.microsoft.com/technet/security/bulletin/ms07-003.mspx



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