rctempire
September 6th, 2003, 01:47 PM
Taken from http://www.newsfactor.com/perl/story/22221.html
Five new flaws have been found in Microsoft (Nasdaq: MSFT) Office, one of which was deemed "critical" by the company in a technical bulletin that provided patches for the holes. The vulnerabilities are particularly glaring, because they affect a wide variety of Microsoft software. Moreover, in at least one case, the flaw was unearthed not by a techie whose job is to attack Microsoft code, but by a typical end-user who created a Microsoft Word template the wrong way.
The critical flaw in Visual Basic for Applications affects some versions of Microsoft Access, Excel, PowerPoint and Word. According to the company's security bulletin, when a document is opened by an application that supports Visual Basic for Applications, the host carries out a check to determine if Microsoft VBA is required by the document and should therefore be loaded. During the initial check, some document properties are passed to Microsoft VBA. The flaw exists because VBA does not correctly validate the data that is passed to it.
As a result, an attacker could create a document with a VBA application designed to accomplish a buffer overflow. If successful, the attacker could run arbitrary code "in the context of the logged-on user," Microsoft said. For an attacker to be successful, the user would have to open a specially crafted document sent by the attacker.
In the case where Microsoft Word is being used as the HTML e-mail editor for Outlook, however, the document could be an e-mail attachment that the user would only have to reply to or forward to trigger the attack.
The one factor possibly mitigating the flaw is that the malicious code could only run with the same rights as the logged-on user. Any limitations on a user's account would also restrict the actions of the malicious code, Microsoft said.
Finding Word Holes
A Microsoft Word and Microsoft Works flaw deemed "important" involves Word's macro security model. Microsoft said vulnerability exists in Word that could allow an attacker armed with a malicious document to bypass security and add, change or delete data or files; communicate with a Web site; or format a hard drive.
If the attacker's document were opened, the malicious macro could execute automatically, regardless of the macro security-level setting. Again, however, the attacker would have to persuade a user to open a document attached to an e-mail.
Jim Bassett, a developer at Practitioners Publishing Company, reported the flaw to Microsoft. Bassett said that he discovered the flaw when a non-technical coworker sent him a Word template that had been created a certain way. Bassett noticed that any Word documents derived from the template started "acting strangely." Bassett ran macro code to debug the template and noticed that even if he had the macro security level set to high or even had "disabled macros" checked, the code would get through.
Basset said his coworker accidentally turned a Word document into a template using a special technique that Bassett declined to disclose. Basset said he first reported the problem to Microsoft back in May. "It took a while for Microsoft to solve it all," Bassett said. "The hole still existed in the Office 2003 beta."
Converter Troubles
Another Office-related flaw involves Microsoft’s WordPerfect converter for handling Corel (Nasdaq: CORL) WordPerfect documents. The flaw exists because the converter does not correctly validate "certain parameters" when it opens a WordPerfect document, which could result in a buffer overflow. Again, arbitrary code could be executed from a malicious document. This flaw, deemed "important," affects Word, PowerPoint, FrontPage, Publisher, and Microsoft Works.
A flaw rated "moderate" by Microsoft involves the Microsoft Access database, particularly its Snapshot Viewer. Because Snapshot Viewer does not validate parameters correctly, a buffer overflow could occur when a file is opened and provide a door for the execution of malicious code. This flaw would require the user to visit a Web site that is under the attacker's control. The Snapshot Viewer is available in all versions of Access but is not installed by default.
NetBIOS Leak
The final fault, which was rated "low" in importance by Microsoft, involves the NetBT (NetBIOS over TCP) Name Service, which enables administrators to find a system's IP address given its NetBIOS name.
Microsoft said that under certain conditions, the response to a NetBT Name Service query may contain random data from the target system's memory. The data could be a segment of HTML or other data that resides in memory when the target system responds. An attacker could gain access to private data by sending a query to the target system and then checking to see if the response included any data.
According to Microsoft, if port 137 UDP has been blocked at the firewall, Internet-based attacks would not be possible. This flaw affects some versions of Windows NT, 2000, XP and Server 2003.
Five new flaws have been found in Microsoft (Nasdaq: MSFT) Office, one of which was deemed "critical" by the company in a technical bulletin that provided patches for the holes. The vulnerabilities are particularly glaring, because they affect a wide variety of Microsoft software. Moreover, in at least one case, the flaw was unearthed not by a techie whose job is to attack Microsoft code, but by a typical end-user who created a Microsoft Word template the wrong way.
The critical flaw in Visual Basic for Applications affects some versions of Microsoft Access, Excel, PowerPoint and Word. According to the company's security bulletin, when a document is opened by an application that supports Visual Basic for Applications, the host carries out a check to determine if Microsoft VBA is required by the document and should therefore be loaded. During the initial check, some document properties are passed to Microsoft VBA. The flaw exists because VBA does not correctly validate the data that is passed to it.
As a result, an attacker could create a document with a VBA application designed to accomplish a buffer overflow. If successful, the attacker could run arbitrary code "in the context of the logged-on user," Microsoft said. For an attacker to be successful, the user would have to open a specially crafted document sent by the attacker.
In the case where Microsoft Word is being used as the HTML e-mail editor for Outlook, however, the document could be an e-mail attachment that the user would only have to reply to or forward to trigger the attack.
The one factor possibly mitigating the flaw is that the malicious code could only run with the same rights as the logged-on user. Any limitations on a user's account would also restrict the actions of the malicious code, Microsoft said.
Finding Word Holes
A Microsoft Word and Microsoft Works flaw deemed "important" involves Word's macro security model. Microsoft said vulnerability exists in Word that could allow an attacker armed with a malicious document to bypass security and add, change or delete data or files; communicate with a Web site; or format a hard drive.
If the attacker's document were opened, the malicious macro could execute automatically, regardless of the macro security-level setting. Again, however, the attacker would have to persuade a user to open a document attached to an e-mail.
Jim Bassett, a developer at Practitioners Publishing Company, reported the flaw to Microsoft. Bassett said that he discovered the flaw when a non-technical coworker sent him a Word template that had been created a certain way. Bassett noticed that any Word documents derived from the template started "acting strangely." Bassett ran macro code to debug the template and noticed that even if he had the macro security level set to high or even had "disabled macros" checked, the code would get through.
Basset said his coworker accidentally turned a Word document into a template using a special technique that Bassett declined to disclose. Basset said he first reported the problem to Microsoft back in May. "It took a while for Microsoft to solve it all," Bassett said. "The hole still existed in the Office 2003 beta."
Converter Troubles
Another Office-related flaw involves Microsoft’s WordPerfect converter for handling Corel (Nasdaq: CORL) WordPerfect documents. The flaw exists because the converter does not correctly validate "certain parameters" when it opens a WordPerfect document, which could result in a buffer overflow. Again, arbitrary code could be executed from a malicious document. This flaw, deemed "important," affects Word, PowerPoint, FrontPage, Publisher, and Microsoft Works.
A flaw rated "moderate" by Microsoft involves the Microsoft Access database, particularly its Snapshot Viewer. Because Snapshot Viewer does not validate parameters correctly, a buffer overflow could occur when a file is opened and provide a door for the execution of malicious code. This flaw would require the user to visit a Web site that is under the attacker's control. The Snapshot Viewer is available in all versions of Access but is not installed by default.
NetBIOS Leak
The final fault, which was rated "low" in importance by Microsoft, involves the NetBT (NetBIOS over TCP) Name Service, which enables administrators to find a system's IP address given its NetBIOS name.
Microsoft said that under certain conditions, the response to a NetBT Name Service query may contain random data from the target system's memory. The data could be a segment of HTML or other data that resides in memory when the target system responds. An attacker could gain access to private data by sending a query to the target system and then checking to see if the response included any data.
According to Microsoft, if port 137 UDP has been blocked at the firewall, Internet-based attacks would not be possible. This flaw affects some versions of Windows NT, 2000, XP and Server 2003.