[NT] Cumulative Security Update for Internet Explorer (MS05-020)
From: SecuriTeam (support_at_securiteam.com)
Date: 04/13/05
- Previous message: SecuriTeam: "[NT] Ublog Multiple Vulnerabilities (Cross Site Scripting, Database Disclosure)"
- Messages sorted by: [ date ] [ thread ] [ subject ] [ author ] [ attachment ]
To: list@securiteam.com Date: 13 Apr 2005 11:06:46 +0200
The following security advisory is sent to the securiteam mailing list, and can be found at the SecuriTeam web site: http://www.securiteam.com
- - promotion
The SecuriTeam alerts list - Free, Accurate, Independent.
Get your security news from a reliable source.
http://www.securiteam.com/mailinglist.html
- - - - - - - - -
Cumulative Security Update for Internet Explorer (MS05-020)
------------------------------------------------------------------------
SUMMARY
A remote code execution vulnerability exists in Internet Explorer because
of the way that it handles certain DHTML objects, certain URLs and Content
Advisory files. An attacker could exploit these vulnerabilities by
constructing a malicious Web page. This malicious Web page could
potentially allow remote code execution if a user visited a malicious Web
site.
DETAILS
Affected Software:
* Microsoft Windows 2000 Service Pack 3 and Microsoft Windows 2000
Service Pack 4
* Microsoft Windows XP Service Pack 1 and Microsoft Windows XP Service
Pack 2
* Microsoft Windows XP 64-Bit Edition Service Pack 1 (Itanium)
* Microsoft Windows XP 64-Bit Edition Version 2003 (Itanium)
* Microsoft Windows Server 2003
* Microsoft Windows Server 2003 for Itanium-based Systems
* Microsoft Windows 98, Microsoft Windows 98 Second Edition (SE), and *
Microsoft Windows Millennium Edition (ME) Tested Microsoft Windows
Components:
Affected Components:
* Internet Explorer 5.01 Service Pack 3 on Microsoft Windows 2000 Service
Pack 3:
<http://www.microsoft.com/downloads/details.aspx?FamilyId=6CF45449-03D8-40B8-A4C0-09F413EE8EAB> Download the update
* Internet Explorer 5.01 Service Pack 4 on Microsoft Windows 2000 Service
Pack 4:
<http://www.microsoft.com/downloads/details.aspx?FamilyId=627F8991-7717-4ADE-A5AE-169591B6AAE0> Download the update
* Internet Explorer 5.5 Service Pack 2 on Microsoft Windows Millennium
Edition Review the FAQ section of this bulletin for details about this
version.
* Internet Explorer 6 Service Pack 1 on Microsoft Windows 2000 Service
Pack 3, on Microsoft Windows 2000 Service Pack 4, or on Microsoft Windows
XP Service Pack 1:
<http://www.microsoft.com/downloads/details.aspx?FamilyId=92E5A83D-9131-4B20-915A-A444C51656DC> Download the update
* Internet Explorer 6 Service Pack 1 on Microsoft Windows 98, on
Microsoft Windows 98 SE, or on Microsoft Windows Millennium Edition
Review the FAQ section of this bulletin for details about this version.
* Internet Explorer 6 Service Pack 1 for Microsoft Windows XP 64-Bit
Edition Service Pack 1 (Itanium):
<http://www.microsoft.com/downloads/details.aspx?FamilyId=87241BC0-E1E9-4EFC-A6EC-5413119D3100> Download the update
* Internet Explorer 6 for Microsoft Windows Server 2003:
<http://www.microsoft.com/downloads/details.aspx?FamilyId=88879B7A-3F4D-40D4-ADFD-4BBD8D4D865F> Download the update
* Internet Explorer 6 for Microsoft Windows Server 2003 for Itanium-based
Systems and Microsoft Windows XP 64-Bit Edition Version 2003 (Itanium):
<http://www.microsoft.com/downloads/details.aspx?FamilyId=FF80E80F-862A-4484-BC9D-FE05F966F1F4> Download the update
* Internet Explorer 6 for Microsoft Windows XP Service Pack 2:
<http://www.microsoft.com/downloads/details.aspx?FamilyId=974F9611-6352-4F9C-B258-346C317857C5> Download the update
Non-Affected Software:
* Microsoft Windows Server 2003 Service Pack 1
* Microsoft Windows Server 2003 with SP1 for Itanium-based Systems
* Microsoft Windows Server 2003 x64 Edition
* Microsoft Windows XP Professional x64 Edition
CVE Information:
DHTML Object Memory Corruption Vulnerability -
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2005-0553>
CAN-2005-0553
URL Parsing Memory Corruption Vulnerability -
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2005-0554>
CAN-2005-0554
Content Advisor Memory Corruption Vulnerability -
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2005-0555>
CAN-2005-0555
DHTML Object Memory Corruption Vulnerability - CAN-2005-0553:
A remote code execution vulnerability exists in Internet Explorer because
of the way that it handles certain DHTML objects. An attacker could
exploit the vulnerability by constructing a malicious Web page. This
malicious Web page could allow remote code execution if a user visited a
malicious Web site. An attacker who successfully exploited this
vulnerability could take complete control of an affected system.
DHTML Object Memory Corruption Vulnerability - CAN-2005-0553
A remote code execution vulnerability exists in Internet Explorer because
of the way that it handles certain DHTML objects. An attacker could
exploit the vulnerability by constructing a malicious Web page. This
malicious Web page could allow remote code execution if a user visited a
malicious Web site. An attacker who successfully exploited this
vulnerability could take complete control of an affected system.
Mitigating Factors for DHTML Object Memory Corruption Vulnerability -
CAN-2005-0553:
* In a Web-based attack scenario, an attacker would have to host a Web
site that contains a Web page that is used to exploit this vulnerability.
An attacker could also try to compromise a Web site and have it display
malicious content. An attacker would have no way to force users to visit a
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 or to a site that has been compromised by the attacker.
* 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.
* By default, Outlook Express 6, Outlook 2002, and Outlook 2003 open HTML
e-mail messages in the Restricted sites zone. Additionally, Outlook 2000
opens HTML e-mail messages in the Restricted sites zone if the
<http://www.microsoft.com/office/outlook/evaluation/security.asp> Outlook
E-mail Security Update has been installed. Outlook Express 5.5 Service
Pack 2 opens HTML e-mail messages in the Restricted sites zone if
Microsoft Security Bulletin
<http://go.microsoft.com/fwlink/?LinkId=19527> MS04-018 has been
installed. The Restricted sites zone helps reduce attacks that could try
to exploit this vulnerability.
The risk of attack from the HTML e-mail vector can be significantly
reduced if you meet all the following conditions:
* Apply the update that is included with Microsoft Security Bulletin
<http://go.microsoft.com/fwlink?linkid=19873> MS03-040 or a later
Cumulative Security Update for Internet Explorer.
* Use Microsoft Outlook Express 6 or a later version in its default
configuration.
* Use Microsoft Outlook 2000 Service Pack 2 or a later version in its
default configuration.
* The vulnerability could not 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 or click a link in an e-mail message.
* By default, Internet Explorer on Windows Server 2003 runs in a
restricted mode that is known as
<http://msdn.microsoft.com/library/default.asp?url=/workshop/security/szone/overview/esc_changes.asp> Enhanced Security Configuration. This mode mitigates this vulnerability. See the FAQ section of this vulnerability for more information about Internet Explorer Enhanced Security Configuration.
Workarounds for DHTML Object Memory Corruption Vulnerability -
CAN-2005-0553:
Microsoft has tested the following workarounds. While 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.
* Set Internet and Local intranet security zone settings to High to
prompt before running Active Scripting in these zones.
You can help protect against this vulnerability by changing your settings
for the Internet security zone to prompt before running Active Scripting.
You can do this by setting your browser security to High.
To raise the browsing security level in Microsoft Internet Explorer,
follow these steps:
1. On the Internet Explorer Tools menu, click Internet Options.
2. In the Internet Options dialog box, click the Security tab, and then
click the Internet icon.
3. Under Security level for this zone, move the slider to High. This sets
the security level for all Web sites you visit to High.
Note If no slider is visible, click Default Level, and then move the
slider to High.
Note Setting the level to High may cause some Web sites to work
incorrectly. If you have difficulty using a Web site after you change this
setting, and you are sure the site is safe to use, you can add that site
to your list of trusted sites. This will allow the site to work correctly
even with the high security setting. See the Restrict Web sites to only
your trusted Web sites workaround for information about how you can add
sites to the Trusted sites zone.
Alternatively, you can change your settings to prompt before running
Active Scripting only. To do this, follow these steps:
1. In Internet Explorer, click Internet Options on the Tools menu.
2. Click the Security tab.
3. Click Internet, and then click Custom Level.
4. Under Settings, in the Scripting section, under Active Scripting, click
Prompt, and then click OK.
5. Click Local intranet, and then click Custom Level.
6. Under Settings, in the Scripting section, under Active Scripting, click
Prompt.
7. Click OK two times to return to Internet Explorer.
Impact of Workaround: There are side effects to prompting before running
Active Scripting. Many Web sites that are on the Internet or on an
intranet use Active Scripting to provide additional functionality.
Prompting before running Active Scripting controls is a global setting
that affects all Internet and intranet sites. You will be prompted
frequently when you enable this workaround. For each prompt, if you feel
you trust the site that you are visiting, click Yes to run Active
Scripting. If you do not want to be prompted for all these sites, use the
"Restrict Web sites to only your trusted Web sites" workaround.
* Restrict Web sites to only your trusted Web sites.
After you set Internet Explorer to require a prompt before it runs Active
Scripting in the Internet zone and in the Local intranet zone, you can add
sites that you trust to Internet Explorer's Trusted sites zone. This will
allow you to continue to use trusted Web sites exactly as you do today,
while helping to protect you from this attack on untrusted sites. We
recommend that you add only sites that you trust to the Trusted sites
zone.
To do this, follow these steps:
1. In Internet Explorer, click Tools, click Internet Options, and then
click the Security tab.
2. In the Select a Web content zone to specify its current security
settings box, click Trusted Sites, and then click Sites.
3. If you want to add sites that do not require an encrypted channel,
click to clear the Require server verification (https:) for all sites in
this zone check box.
4. In the Add this Web site to the zone box, type the URL of a site that
you trust, and then click Add.
5. Repeat these steps for each site that you want to add to the zone.
6. Click OK two times to accept the changes and return to Internet
Explorer.
Add any sites that you trust not to take malicious action on your
computer. One in particular that you may want to add is
"*.windowsupdate.microsoft.com" (without the quotation marks). This is the
site that will host the update, and it requires an ActiveX control to
install the update.
* Install the update that is described in Microsoft Security Bulletin
<http://go.microsoft.com/fwlink/?LinkId=19527> MS04-018 if you are using
Outlook Express 5.5 SP2.
Outlook Express 5.5 Service Pack 2 opens HTML e-mail messages in the
Restricted sites zone if Microsoft Security Bulletin MS04-018 has been
installed.
Customers who use one or more of these products could be at a reduced risk
from an e-mail-borne attack that tries to exploit this vulnerability
unless the user clicks a malicious link in the e-mail message.
* Read e-mail messages in plain text format if you are using Outlook 2002
or a later version, or Outlook Express 6 SP1 or a later version, to help
protect yourself from the HTML e-mail attack vector.
Microsoft Outlook 2002 users who have applied Office XP Service Pack 1 or
a later version and Microsoft Outlook Express 6 users who have applied
Internet Explorer 6 Service Pack 1 or a later version can enable this
setting and view e-mail messages that are not digitally signed or e-mail
messages that are not encrypted in plain text only.
Digitally signed e-mail messages or encrypted e-mail messages are not
affected by the setting and may be read in their original formats. For
more information about how to enable this setting in Outlook 2002, see
<http://support.microsoft.com/kb/307594> Microsoft Knowledge Base Article
307594.
For information about this setting in Outlook Express 6, see
<http://support.microsoft.com/kb/291387> Microsoft Knowledge Base Article
291387.
Impact of Workaround: E-mail messages that are viewed in plain text format
will not contain pictures, specialized fonts, animations, or other rich
content. Additionally:
* The changes are applied to the preview pane and to open messages.
Pictures become attachments so that they are not lost.
Because the message is still in Rich Text or HTML format in the store, the
object model (custom code solutions) may behave unexpectedly.
FAQ for DHTML Object Memory Corruption Vulnerability - CAN-2005-0553:
What is the scope of the vulnerability?
This is a remote code execution vulnerability. 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 impacted
than users who operate with administrative user rights.
What causes the vulnerability?
A race condition could occur in Internet Explorer when it processes DHTML
objects.
What are DHTML objects?
The Dynamic HTML (DHTML) object model allows for more dynamic content on
Web pages than HTML. For more information about DHTML, see the
<http://msdn.microsoft.com/workshop/author/dhtml/dhtml_node_entry.asp>
product documentation.
What is a race condition?
A race condition is typically associated with synchronization errors that
provide a window of opportunity during which one process can interfere
with another potentially introducing a remote code execution
vulnerability. Race conditions may for example occur as a result of the
relative timing of events in multithreaded operating systems and software.
Race conditions are frequently difficult to exploit in predictable ways.
For more information about race conditions, see the
<http://msdn.microsoft.com/library/en-us/cpguide/html/cpconmanagedthreadingbestpractices.asp> MSDN Library Web site.
Why does this race condition cause a vulnerability?
This race condition could create an environment where a series of
specially timed requests could cause the Internet Explorer to perform an
unpredictable action. However, because the circumstances that lead to this
condition could change every time that the vulnerability is exploited, it
may be difficult for an attacker to exploit this vulnerability.
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 exploit this vulnerability by creating a malicious Web
page or an HTML e-mail message and then persuading the user to visit the
page or to view the HTML e-mail message. If the user visited the page or
viewed the e-mail message, the attacker could access information from
other Web sites, could access local files on the system, or could cause
malicious code to run in the security context of the locally logged on
user. The vulnerability could not 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 or click a link in an e-mail message.
What systems are primarily at risk from the vulnerability?
This vulnerability requires that a user is logged on and reading e-mail or
visiting Web sites for any malicious action to occur. Therefore, any
systems where e-mail is read or where Internet Explorer is used
frequently, such as users workstations or terminal servers, are at the
most risk from this vulnerability. Systems that are not typically used to
read e-mail or to visit Web sites, such as most server systems, are at a
reduced risk.
I am running Internet Explorer on Windows Server 2003. Does this mitigate
this vulnerability?
Yes. By default, Internet Explorer on Windows Server 2003 runs in a
restricted mode that is known as
<http://msdn.microsoft.com/library/default.asp?url=/workshop/security/szone/overview/esc_changes.asp> Enhanced Security Configuration. This mode mitigates this vulnerability.
What is Internet Explorer Enhanced Security Configuration?
Internet Explorer Enhanced Security Configuration is a group of
preconfigured Internet Explorer settings that reduce the likelihood of a
user or of an administrator downloading and running malicious Web content
on a server. Internet Explorer Enhanced Security Configuration reduces
this risk by modifying many security-related settings. This includes the
settings on the Security tab and on the Advanced tab in the Internet
Options dialog box. Some of the important modifications include the
following:
* The security level for the Internet zone is set to High. This setting
disables scripts, ActiveX controls, Microsoft Java Virtual Machine
(MSJVM), and file downloads.
* Automatic detection of intranet sites is disabled. This setting assigns
all intranet Web sites and all Universal Naming Convention (UNC) paths
that are not explicitly listed in the Local intranet zone to the Internet
zone.
* Install On Demand and non-Microsoft browser extensions are disabled.
This setting prevents Web pages from automatically installing components
and prevents non-Microsoft extensions from running.
* Multimedia content is disabled. This setting prevents music,
animations, and video clips from running.
What does the update do?
The update removes the vulnerability by modifying the way Internet
Explorer synchronizes the threads that are being used to process the
specially crafted messages.
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.
URL Parsing Memory Corruption Vulnerability - CAN-2005-0554
A remote code execution vulnerability exists in Internet Explorer because
of the way that it handles certain URLs. An attacker could exploit the
vulnerability by constructing a malicious Web page. This malicious Web
page could potentially allow remote code execution if a user visited a
malicious Web site. An attacker who successfully exploited this
vulnerability could take complete control of an affected system.
Mitigating Factors for URL Parsing Memory Corruption Vulnerability -
CAN-2005-0554:
* In a Web-based attack scenario, an attacker would have to host a Web
site that contains a Web page that is used to exploit this vulnerability.
An attacker could also try to compromise a Web site and have it display
malicious content. An attacker would have no way to force users to visit a
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 or to a site that has been compromised by the attacker.
* 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.
* By default, Outlook Express 6, Outlook 2002, and Outlook 2003 open HTML
e-mail messages in the Restricted sites zone. Additionally, Outlook 2000
opens HTML e-mail messages in the Restricted sites zone if the
<http://www.microsoft.com/office/outlook/evaluation/security.asp> Outlook
E-mail Security Update has been installed. Outlook Express 5.5 Service
Pack 2 opens HTML e-mail messages in the Restricted sites zone if
Microsoft Security Bulletin
<http://go.microsoft.com/fwlink/?LinkId=19527> MS04-018 has been
installed. The Restricted sites zone helps reduce attacks that could try
to exploit this vulnerability.
The risk of attack from the HTML e-mail vector can be significantly
reduced if you meet all the following conditions:
* Apply the update that is included with Microsoft Security Bulletin
<http://go.microsoft.com/fwlink?linkid=19873> MS03-040 or a later
Cumulative Security Update for Internet Explorer.
* Use Microsoft Outlook Express 6 or a later version in its default
configuration.
* Use Microsoft Outlook 2000 Service Pack 2 or a later version in its
default configuration.
* The vulnerability could not be exploited automatically through e-mail.
For an attack to be successful, a user must click a malicious link that is
sent in an e-mail message.
Workarounds for URL Parsing Memory Corruption Vulnerability -
CAN-2005-0554:
Microsoft has tested the following workarounds. While 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.
* Set Internet and Local intranet security zone settings to High to
prompt before running Active Scripting in these zones.
You can help protect against this vulnerability by changing your settings
for the Internet security zone to prompt before running Active Scripting.
You can do this by setting your browser security to High.
Note This workaround provides limited protection and there are known
attack vectors that do not rely on Active Scripting.
To raise the browsing security level in Microsoft Internet Explorer,
follow these steps:
1. On the Internet Explorer Tools menu, click Internet Options.
2. In the Internet Options dialog box, click the Security tab, and then
click the Internet icon.
3. Under Security level for this zone, move the slider to High. This sets
the security level for all Web sites you visit to High.
Note If no slider is visible, click Default Level, and then move the
slider to High.
Note Setting the level to High may cause some Web sites to work
incorrectly. If you have difficulty using a Web site after you change this
setting, and you are sure the site is safe to use, you can add that site
to your list of trusted sites. This will allow the site to work correctly
even with the high security setting.
Alternatively, you can change your settings to prompt before running
Active Scripting only. To do this, follow these steps:
1. In Internet Explorer, click Internet Options on the Tools menu.
2. Click the Security tab.
3. Click Internet, and then click Custom Level.
4. Under Settings, in the Scripting section, under Active Scripting, click
Prompt, and then click OK.
5. Click Local intranet, and then click Custom Level.
6. Under Settings, in the Scripting section, under Active Scripting, click
Prompt.
7. Click OK two times to return to Internet Explorer.
Impact of Workaround: There are side effects to prompting before running
Active Scripting. Many Web sites that are on the Internet or on an
intranet use Active Scripting to provide additional functionality.
Prompting before running Active Scripting controls is a global setting
that affects all Internet and intranet sites. You will be prompted
frequently when you enable this workaround. For each prompt, if you feel
you trust the site that you are visiting, click Yes to run Active
Scripting. If you do not want to be prompted for all these sites, use the
"Restrict Web sites to only your trusted Web sites" workaround.
* Restrict Web sites to only your trusted Web sites.
After you set Internet Explorer to require a prompt before it runs Active
Scripting in the Internet zone and in the Local intranet zone, you can add
sites that you trust to Internet Explorer's Trusted sites zone. This will
allow you to continue to use trusted Web sites exactly as you do today,
while helping to protect you from this attack on untrusted sites. We
recommend that you add only sites that you trust to the Trusted sites
zone.
To do this, follow these steps:
1. In Internet Explorer, click Tools, click Internet Options, and then
click the Security tab.
2. In the Select a Web content zone to specify its current security
settings box, click Trusted Sites, and then click Sites.
3. If you want to add sites that do not require an encrypted channel,
click to clear the Require server verification (https:) for all sites in
this zone check box.
4. In the Add this Web site to the zone box, type the URL of a site that
you trust, and then click Add.
5. Repeat these steps for each site that you want to add to the zone.
6. Click OK two times to accept the changes and return to Internet
Explorer.
Add any sites that you trust not to take malicious action on your
computer. One in particular that you may want to add is
"*.windowsupdate.microsoft.com" (without the quotation marks). This is the
site that will host the update, and it requires an ActiveX control to
install the update.
* Install the update that is described in Microsoft Security Bulletin
<http://go.microsoft.com/fwlink/?LinkId=19527> MS04-018 if you are using
Outlook Express 5.5 SP2.
Outlook Express 5.5 Service Pack 2 opens HTML e-mail messages in the
Restricted sites zone if Microsoft Security Bulletin MS04-018 has been
installed.
Customers who use one or more of these products could be at a reduced risk
from an e-mail-borne attack that tries to exploit this vulnerability
unless the user clicks a malicious link in the e-mail message.
* Read e-mail messages in plain text format if you are using Outlook 2002
or a later version, or Outlook Express 6 SP1 or a later version, to help
protect yourself from the HTML e-mail attack vector.
Microsoft Outlook 2002 users who have applied Office XP Service Pack 1 or
a later version and Microsoft Outlook Express 6 users who have applied
Internet Explorer 6 Service Pack 1 or a later version can enable this
setting and view e-mail messages that are not digitally signed or e-mail
messages that are not encrypted in plain text only.
Digitally signed e-mail messages or encrypted e-mail messages are not
affected by the setting and may be read in their original formats. For
more information about how to enable this setting in Outlook 2002, see
<http://support.microsoft.com/kb/307594> Microsoft Knowledge Base Article
307594.
For information about this setting in Outlook Express 6, see
<http://support.microsoft.com/kb/291387> Microsoft Knowledge Base Article
291387.
Impact of Workaround: E-mail messages that are viewed in plain text format
will not contain pictures, specialized fonts, animations, or other rich
content. Additionally:
* The changes are applied to the preview pane and to open messages.
Pictures become attachments so that they are not lost.
Because the message is still in Rich Text or HTML format in the store, the
object model (custom code solutions) may behave unexpectedly.
FAQ for URL Parsing Memory Corruption Vulnerability - CAN-2005-0554:
What is the scope of the vulnerability?
This is a remote code execution vulnerability. 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 impacted
than users who operate with administrative user rights.
What causes the vulnerability?
The process used by Internet Explorer to validate the buffer used when it
processes certain URLs.
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 exploit this vulnerability by creating a malicious Web
page or an HTML e-mail message and then persuading the user to visit the
page or to view the HTML e-mail message. If the user visited the page or
viewed the e-mail message, the attacker could access information from
other Web sites, could access local files on the system, or could cause
malicious code to run in the security context of the locally logged on
user. The vulnerability could not be exploited automatically through
e-mail. For an attack to be successful, a user must click a malicious link
that is sent in an e-mail message.
What systems are primarily at risk from the vulnerability?
This vulnerability requires that a user is logged on and reading e-mail or
visiting Web sites for any malicious action to occur. Therefore, any
systems where e-mail is read or where Internet Explorer is used
frequently, such as users workstations or terminal servers, are at the
most risk from this vulnerability. Systems that are not typically used to
read e-mail or to visit Web sites, such as most server systems, are at a
reduced risk.
What does the update do?
The update removes the vulnerability by modifying the way that Internet
Explorer validates the length of a message 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.
Content Advisor Memory Corruption Vulnerability - CAN-2005-0555
A remote code execution vulnerability exists in Internet Explorer because
of the way that it handles Content Advisor files. An attacker could
exploit the vulnerability by constructing a specially crafted Content
Advisor file. This malicious Content Advisor file could potentially allow
remote code execution if a user visited a malicious Web site or viewed a
malicious e-mail message and accepted the installation of the file. An
attacker who successfully exploited this vulnerability could take complete
control of an affected system. However, significant user interaction is
required to exploit this vulnerability.
Mitigating Factors for Content Advisor Memory Corruption Vulnerability -
CAN-2005-0555:
* In a Web-based attack scenario, an attacker would have to host a Web
site that contains a Web page that is used to exploit this vulnerability.
An attacker could also try to compromise a Web site and have it display
malicious content. An attacker would have no way to force users to visit a
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 or to a site that has been compromised by the attacker. A
user would then have to click through a series of Content Advisor setup
windows for an attack to be successful.
* 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.
* By default, Outlook Express 6, Outlook 2002, and Outlook 2003 open HTML
e-mail messages in the Restricted sites zone. Additionally, Outlook 2000
opens HTML e-mail messages in the Restricted sites zone if the Outlook
E-mail Security Update has been installed. Outlook Express 5.5 Service
Pack 2 opens HTML e-mail messages in the Restricted sites zone if
Microsoft Security Bulletin MS04-018 has been installed. The Restricted
sites zone helps reduce attacks that could try to exploit this
vulnerability.
The risk of attack from the HTML e-mail vector can be significantly
reduced if you meet all the following conditions:
* Apply the update that is included with Microsoft Security Bulletin
MS03-040 or a later Cumulative Security Update for Internet Explorer.
* Use Microsoft Outlook Express 6 or a later version in its default
configuration.
* Use Microsoft Outlook 2000 Service Pack 2 or a later version in its
default configuration.
* The vulnerability could not be exploited automatically through e-mail.
For an attack to be successful, a user must open an attachment this is
sent in an e-mail message and then click through a series of Content
Advisor setup windows.
FAQ for Content Advisor Memory Corruption Vulnerability - CAN-2005-0555:
What is the scope of the vulnerability?
This is a remote code execution vulnerability. 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 impacted
than users who operate with administrative user rights.
What causes the vulnerability?
The process used by Internet Explorer to validate the buffer used when it
processes certain Content Advisor content.
What is the Internet Explorer Content Advisor?
Internet Explorer Content Advisor allows you to rate the appropriateness
of Web content and to control which Web sites your users can visit. This
feature is intended to be used to define a more secure environment that
help protect your users from content on the Internet that is not
appropriate. For more information about the Content Advisor, see the
<http://www.microsoft.com/resources/documentation/ie/6/all/reskit/en-us/part2/c05ie6rk.mspx> product documentation.
Microsoft IIS Web server administrators can rate content in support of the
Internet Explorer Content Advisor on a Web site by using content ratings.
For more information about content ratings, see the
<http://www.microsoft.com/resources/documentation/iis/6/all/proddocs/en-us/pub_ucr.mspx> product documentation.
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 exploit this vulnerability by creating a malicious Web
page or an HTML e-mail message and then persuading the user to visit the
page or to view the HTML e-mail message. If the user visited the page or
viewed the e-mail message, the attacker could access information from
other Web sites, could access local files on the system, or could cause
malicious code to run in the security context of the locally logged on
user. A user would then have to click through a series of Content Advisor
setup windows for an attack to be successful.
An attacker could also send a content ratings file (.rat) in e-mail and
persuade a user to install it. A user would have to click through a series
of Content Advisor setup windows for an attack to be successful.
If the content ratings file on an IIS Web server has been replaced with a
malicious content ratings file, an attacker could cause code execution on
the Web server. However, the Web server would already have been
compromised because the file resides in an area where, by default, only
Administrators have write access. This update also addresses this vector.
What systems are primarily at risk from the vulnerability?
This vulnerability requires that a user is logged on and reading e-mail or
visiting Web sites for any malicious action to occur. Therefore, any
systems where e-mail is read or where Internet Explorer is used
frequently, such as users workstations or terminal servers, are at the
most risk from this vulnerability. Systems that are not typically used to
read e-mail or to visit Web sites, such as most server systems, are at a
reduced risk.
What does the update do?
The update removes the vulnerability by modifying the way that Internet
Explorer validates the length of a message 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.
ADDITIONAL INFORMATION
The original article can be found at:
<http://www.microsoft.com/technet/security/bulletin/MS05-020.mspx>
http://www.microsoft.com/technet/security/bulletin/MS05-020.mspx
========================================
This bulletin is sent to members of the SecuriTeam mailing list.
To unsubscribe from the list, send mail with an empty subject line and body to: list-unsubscribe@securiteam.com
In order to subscribe to the mailing list, simply forward this email to: list-subscribe@securiteam.com
====================
====================
DISCLAIMER:
The information in this bulletin is provided "AS IS" without warranty of any kind.
In no event shall we be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages.
- Previous message: SecuriTeam: "[NT] Ublog Multiple Vulnerabilities (Cross Site Scripting, Database Disclosure)"
- Messages sorted by: [ date ] [ thread ] [ subject ] [ author ] [ attachment ]
Relevant Pages
|
|
