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Credit:
The information has been provided by MS07-023.
The original article can be found at:
http://www.microsoft.com/technet/security/bulletin/ms07-023.mspx
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Affected Software:
* Microsoft Office 2000 Service Pack 3
* Microsoft Excel 2000 - Download the update (KB934447)
* Microsoft Office XP Service Pack 3
* Microsoft Excel 2002 - Download the update (KB934453)
* Microsoft Office 2003 Service Pack 2
* Microsoft Excel 2003 - Download the update (KB933666)
* Microsoft Excel 2003 Viewer - Download the update (KB934445)
* 2007 Microsoft Office System
* Microsoft Office Excel 2007 - Download the update (KB934670)
* Microsoft Office Compatibility Pack for Word, Excel, and PowerPoint 2007 File Formats - Download the update (KB933688)
* Microsoft Office 2004 for Mac - Download the update (KB936749)
Non-Affected Software:
* Microsoft Works Suites:
* Microsoft Works Suite 2004
* Microsoft Works Suite 2005
* Microsoft Works Suite 2006
Excel BIFF Record Vulnerability - CVE-2007-0215:
A remote code execution vulnerability exists in the way Excel handles files with malformed BIFF records. Such a file might be included in an e-mail attachment or hosted on a malicious Web site. An attacker could exploit the vulnerability by constructing a specially crafted Excel file that could allow remote code execution.
Mitigating Factors for Excel BIFF Record Vulnerability - CVE-2007-0215:
* 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 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 specially crafted 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.
* Users who have installed and are using the Office Document Open Confirmation Tool for Office 2000 will be prompted with Open, Save, or Cancel before opening a document. The features of the Office Document Open Confirmation Tool are incorporated in Office XP and Office 2003.
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Workarounds for Excel BIFF Record Vulnerability - CVE-2007-0215:
Do not open or save Microsoft Excel 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 Excel BIFF Record Vulnerability - CVE-2007-0215:
What is the scope of the vulnerability?
A remote code execution vulnerability exists in the way Excel handles Excel files with malformed BIFF records. An attacker could exploit the vulnerability by constructing a specially crafted Excel file that could allow remote code execution.
What causes the vulnerability?
The vulnerability is caused by Excel not correctly handling Excel files with malformed BIFF records, which could result in the corruption of memory in such a way that an attacker could execute arbitrary code.
What might an attacker use the vulnerability to do?
An attacker who successfully exploited this vulnerability could cause arbitrary code to run with the privileges of the user who opened the file.
How could an attacker exploit the vulnerability?
In an e-mail attack scenario, an attacker could exploit the vulnerability by sending a specially-crafted file to the user and by convincing the user to open the file.
In a Web-based attack scenario, an attacker would have to host a Web site that contains an Excel 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 specially crafted Web site. Instead, an attacker would have to convince them to visit the Web site, typically by getting them to click a link that takes them to the attacker's site.
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 Excel handles malformed BIFF records.
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.
Excel Set Font Vulnerability - CVE-2007-1203:
A remote code execution vulnerability exists in the way Excel handles Excel files with specially crafted set font values. Such a file might be included in an e-mail attachment or hosted on a malicious Web site. An attacker could exploit the vulnerability by constructing a specially crafted Excel file that could allow remote code execution.
Mitigating Factors for Excel Set Font Vulnerability - CVE-2007-1203:
* 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 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 specially crafted 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.
* Users who have installed and are using the Office Document Open Confirmation Tool for Office 2000 will be prompted with Open, Save, or Cancel before opening a document. The features of the Office Document Open Confirmation Tool are incorporated in Office XP and Office 2003.
Workarounds for Excel Set Font Vulnerability - CVE-2007-1203:
Do not open or save Microsoft Excel 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 Excel Set Font Vulnerability - CVE-2007-1203:
What is the scope of the vulnerability?
A remote code execution vulnerability exists in the way Excel handles Excel files with specially crafted set font values. Such a file might be included in an e-mail attachment or hosted on a malicious Web site. An attacker could exploit the vulnerability by constructing a specially crafted Excel file that could allow remote code execution.
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?
The vulnerability is caused by Excel not correctly handling Excel files with a specially crafted set font value, which will results in the corruption of memory.
What might an attacker use the vulnerability to do?
An attacker who successfully exploited this vulnerability could cause arbitrary code to run with the privileges of the user who opened the file.
How could an attacker exploit the vulnerability?
In an e-mail attack scenario, an attacker could exploit the vulnerability by sending a specially-crafted file to the user and by convincing the user to open the file.
In a Web-based attack scenario, an attacker would have to host a Web site that contains an Excel file that is used to attempt to exploit this vulnerability. An attacker would have no way to force users to visit a specially crafted Web site and open an Excel file. Instead, an attacker would have to convince them to visit the Web site, typically by getting them to click a link that takes them to the attacker's site.
What systems are primarily at risk from the vulnerability?
Workstations and terminal servers that have Microsoft Excel installed 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 Excel handles set font values before passing it 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. 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.
Excel Filter Record Vulnerability CVE-2007-1214:
A remote code execution vulnerability exists in the way Excel handles Excel files with specially crafted filter records. Such a file might be included in an e-mail attachment or hosted on a malicious Web site. An attacker could exploit the vulnerability by constructing a specially crafted Excel file that could allow remote code execution.
Mitigating Factors for Excel Filter Record Vulnerability CVE-2007-1214:
* 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 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 specially crafted 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.
* Users who have installed and are using the Office Document Open Confirmation Tool for Office 2000 will be prompted with Open, Save, or Cancel before opening a document. The features of the Office Document Open Confirmation Tool are incorporated in Office XP and Office 2003.
Workarounds for Excel Filter Record Vulnerability CVE-2007-1214:
Do not open or save Microsoft Excel 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 Excel Filter Record Vulnerability CVE-2007-1214:
What is the scope of the vulnerability?
A remote code execution vulnerability exists in the way Excel handles Excel files with specially crafted values. Such a file might be included in an e-mail attachment or hosted on a malicious Web site. An attacker could exploit the vulnerability by constructing a specially crafted Excel file that could allow remote code execution.
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?
When Excel opens a specially crafted Excel file with a specially crafted filter record, it may corrupt memory in such a way that an attacker could execute arbitrary code.
What might an attacker use the vulnerability to do?
An attacker who successfully exploited this vulnerability could cause arbitrary code to run with the privileges of the user who opened the file.
How could an attacker exploit the vulnerability?
In an e-mail attack scenario, an attacker could exploit the vulnerability by sending a specially-crafted file to the user and by convincing the user to open the file.
In a Web-based attack scenario, an attacker would have to host a Web site that contains an Excel 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 specially crafted Web site. Instead, an attacker would have to convince them to visit the Web site, typically by getting them to click a link that takes them to the attacker's site.
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 Excel validates filter records before passing it 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. 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.
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