Functional code that demonstrates an exploit of the Microsoft Office Excel object processing stack overflow vulnerability is publicly available.
Microsoft Office Excel contains a vulnerability that could allow an unauthenticated, remote attacker to execute arbitrary code.
The vulnerability is due to insufficient boundary restrictions when Microsoft Office Excel processes malformed objects. An unauthenticated, remote attacker could exploit this vulnerability by convincing a user to view a malicious Excel file. If the user views the file, the attacker could execute arbitrary code with the privileges of the user.
Functional code that demonstrates an exploit of this vulnerability is publicly available.
Microsoft has confirmed this vulnerability in a security bulletin and released software updates that correct it.
The following Microsoft products are affected:
Office Excel 2002 SP3 and prior
Office 2004 for Mac
Office 2008 for Mac
Open XML File Format Converter for Mac
Attackers cannot directly exploit this vulnerability and instead must engage users to participate in an exploit. Attackers must convince a user to open a malicious document, likely by providing a document directly to the user, most often as an e-mail attachment. Documents may also be placed on public websites or spread using file sharing services. The attacker may employ social engineering techniques in an attempt to make users more interested in opening the document, increasing the likelihood of a successful exploit.
Microsoft has released a security bulletin at the following link: MS10-038
An unauthenticated, remote attacker could exploit this vulnerability to execute arbitrary code with the privileges of the user. If the user holds elevated privileges, the attacker could execute code that results in a complete compromise.
The vulnerability is due to insufficient boundary restrictions when Microsoft Office Excel processes malformed objects. An unauthenticated, remote attacker could exploit this vulnerability by convincing a user to view a malicious document. The processing of malicious objects in the document could trigger a stack overflow, corrupting memory. The attacker could use the memory corruption to execute arbitrary code with the privileges of the user.
Administrators are advised to apply the appropriate updates.
Users are advised not to open e-mail messages from suspicious or unrecognized sources. If users cannot verify that links or attachments included in e-mail messages are safe, they are advised not to open them.
Users are advised to run applications with the least necessary privileges.
Users may consider applying the Microsoft Office Isolated Conversion Environment (MOICE) to safely open Word, Excel, and PowerPoint files from suspicious or unrecognized sources on systems that are running Microsoft Office 2003 or Office 2007.
Administrators may consider using the Microsoft Baseline Security Analyzer (MBSA) scan tool to identify common security misconfigurations and missing security updates on system endpoints.
Administrators are advised to monitor critical systems.
Microsoft customers can obtain updates directly by using the links in the security bulletin. These updates are also distributed by Windows automatic update features and available on the Windows Update website. Microsoft Windows Server Update Services (WSUS), Systems Management Server, and System Center Configuration Manager can assist administrators in deploying software updates.
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