Tucked within Tuesday's bevy of security bulletins is a critical update for versions of Microsoft Exchange Server. The vulnerabilities, however, are not within the code for Exchange, but are instead in the Oracle Outside In technology used by the products to enable them to access and transform various file formats.
According to Microsoft, in Microsoft Exchange Server 2007 and Exchange Server 2010, Outlook Web App (OWA) users have a feature called WebReady Document Viewing, which allows them to view some attachments as a Web page instead of relying on local applications to open/view it. To support the WebReady feature, Oracle Outside In is used by the conversion process in the server back-end.
In Microsoft Exchange Server 2007 and 2010, the vulnerabilities make it possible under certain circumstances for an attacker to use the vulnerabilities to take control of the server process that is parsing a specially crafted file. An attacker could then install programs or take any other action the server process has access to, according to Microsoft.
Marcus Carey, security researcher at Rapid7, tells Dark Reading that the vulnerability appears to be an excellent option for spear-phishing attempts since it can compromise the server simply by a legitimate user opening a malicious document using Outlook Web App (OWA). From there, an attacker can escalate privileges, he says.
"It's interesting that Microsoft labels this 'critical,' while Oracle listed the vulnerability in their Critical Patch Update with a base score of 2.1, which is very low," Carey says. "After MS12-052, MS12-058 should be an organization's second priority to patch."
Oracle Outside In has had many vulnerabilities in the past, says BeyondTrust CTO Marc Maiffret.
"This vulnerability is not only particularly critical because of its ability to compromise Exchange, but also because of the track record that Oracle's Outside In technology has from a security perspective," he says, adding that the patch should be applied "as soon as possible if you are using Microsoft Exchange and OWA."
Customers can also implement the workaround in Microsoft Security Advisory 2737111 to disable WebReady Document Viewing in lieu of applying the patch. The vulnerabilities also affect FAST Search Server 2010 for SharePoint, but the functionality that uses "Oracle Outside In" is not enabled by default and is running with a restricted token similar to the Office 2010 Protected View sandbox that limits what the attacker may access even if the process is compromised, Microsoft notes.
The good news is that the vulnerabilities covered by the bulletin are not known to be under attack.
"This vulnerability really never went anywhere in the exploit community," says Andrew Storms, director of security operations at nCircle. "We have so far seen very little uptake on actively exploiting the bug."
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