- These vulnerabilities affect: Exchange Server 2007 and 2010
- How an attacker exploits it: By enticing an email user to preview a specially crafted email attachment or to visit a malicious RSS feed.
- Impact: An attacker can execute code with the restricted privileges of the LocalService account, or crash your email server
- What to do: Deploy the appropriate Exchange Server update as soon as possible, or let Windows Automatic Update do it for you
Microsoft Exchange is one of the most popular email servers used today. Today’s Exchange bulletin describes two Critical security vulnerabilities. We highlight these flaws below:
- The first is another remote code execution vulnerability in the Oracle’s Outside In technology. In our last Exchange alert, we described a feature called WebReady Document Viewing, which allows your email users to preview attached documents as web pages. Exchange leverages Oracle’s Outside In technology to parse these documents and provide these previews. Today’s update fixes more Oracle Outside In vulnerabilities similar to the ones we described in August. In a nutshell, if an attacker can entice one of your email users to preview a specially crafted attachment, he can exploit these flaws to execute code directly on your Exchange server. Luckily, the code only executes with the permissions of the LocalService account, which has limited privileges.
- Exchange also suffers from a Denial of Service (DoS) flaw related to how it handles specially crafted RSS feeds. If an attacker can lure one of your users into subscribing to a specially malformed RSS feed, he could cause your email server to stop responding, which would have significant business impact. Worse yet, Microsoft warns Exchange could also dismount its database, possibly leading to mailbox and database corruption.
If you manage an Exchange server, we recommend you update immediately. However, we always recommend you test server patches before applying them to production servers.
Microsoft has released Exchange updates to correct these vulnerabilities. You should download, test, and deploy the appropriate update as soon as possible, or let Windows Update do it for you. You can find the updates in the “Affected and Non-Affected Software” section of Microsoft’s Exchange bulletin.
For All WatchGuard Users:
If you like, you can configure WatchGuard’s security appliances to block or strip the document types necessary for attackers to exploit these vulnerabilities. However, some of the affected documents include ones that most administrators prefer to allow, such as Word and PDF documents. Therefore, we recommend you apply the patches instead.
Microsoft has released patches to fix these vulnerabilities.