Severity: Medium
Summary:
- These vulnerabilities affect: Microsoft Office (for PC and Mac), the SharePoint suite of products, and Visual Basic
- How an attacker exploits them: Multiple vectors of attack, including luring your users into opening malicious Office documents, or into visiting web sites with malicious content
- Impact: In the worst case, an attacker can execute code, potentially gaining complete control of your computer
- What to do: Install the appropriate Microsoft updates as soon as you can, or let Windows Update do it for you.
Exposure:
Today, Microsoft released three Office-related security bulletins describing eight vulnerabilities found in various Office and Office-related packages including the SharePoint suite of products, Office for Mac, and Visual Basic. We summarize the bulletins below:
- MS12-046: VBA Insecure Library Loading Vulnerability
Microsoft Visual Basic for Applications (VBA) is a development platform that ships with Office, and helps you create new applications that integrate with existing Office applications and data systems. It suffers from a Dynamic Link Library (DLL) loading class vulnerability, which we’ve described in many previous Microsoft alerts. In a nutshell, this class of flaw involves an attacker enticing one of your users into opening some sort of booby-trapped file from the same location as a maliciously crafted DLL file. If you open the booby-trapped file, it executes code in the malicious DLL file with your privileges. If you have local administrative privileges, the attacker could exploit this type of issue to gain complete control of your computer. In this particular case, the vulnerability is triggered by opening Office documents, such as .docx or xlsx.
Microsoft rating: Important
- MS12-050: Multiple SharePoint Vulnerabilities
SharePoint is Microsoft’s web and document collaboration and management platform. SharePoint, and other related packages, suffer from six new security flaws, including three Cross-Site Scripting vulnerabilities (XSS) that could allow an attacker to elevate his privileges. By enticing one of your users to visit a malicious web page or into clicking a specially crafted link, an attacker could exploit any of the three XSS flaws to gain that user’s privilege on your SharePoint server. This means the attacker could view or change all the documents which that user could. The remaining issues include two information disclosure flaws and a URL redirection vulnerability attackers could leverage in spoofing attacks. See the “Vulnerability Information” security of the bulletin for more details.
Microsoft rating: Important
- MS12-051: Office for Mac Elevation of Privilege Flaw
Office for Mac 2011 (the Apple OS X version of Microsoft’s productivity software) suffers from a vulnerability involving the way it sets folder permissions. If an attacker can gain physical access to your computer, plant a malicious executable in an Office folder, and then entice you to run it, the executable launches with your elevated privileges. Of course, if an attacker already has enough access to your computer to do all this, you already have significant problems. This flaw only poses a marginal risk.
Microsoft rating: Important
Solution Path
Microsoft has released updates that correct these vulnerabilities. You should download, test, and deploy the appropriate patches as soon as you can. If you choose, you can also let Windows Update automatically download and install these updates for you, though we recommend you test server patches before deploying them to production environments.
The links below take you directly to the “Affected and Non-Affected Software” section for each bulletin, where you will find links for the various updates:
For All WatchGuard Users:
Attackers can exploit these vulnerabilities using diverse methods, including by placing files locally. Though you can configure WatchGuard appliances to block some of the Office documents related to a few of these attacks, and you can leverage our security services to mitigate the risk of malware delivered via these attacks, we cannot protect you against all these attacks, especially the local ones. We recommend you apply Microsoft’s patches to best protect your network.
Status:
Microsoft has released updates to fix these vulnerabilities.
References:
This alert was researched and written by Corey Nachreiner, CISSP (@SecAdept).