Microsoft has become aware of targeted cyberattacks leveraging a new vulnerability (CVE-2014-6352) that affects most supported Windows releases, according to an advisory company published by the company on Tuesday.
According to Microsoft, the zero-day impacts Windows Vista, Windows Server 2008, Windows Server 2008 R2, Windows 7, Windows 8, Windows 8.1, Windows Server 2012, Windows Server 2012 R2, Windows RT and Windows RT 8.1. The only supported version of the operating system that’s not affected is Windows Server 2003, for which end of life is July 14, 2015.
The flaw, which exists in the OLE (Object Linking and Embedding) technology, can be exploited for remote code execution if the attacker can convince the targeted user to open a specially crafted Microsoft Office file containing an OLE object.
OLE is a proprietary technology developed by Microsoft designed to allow applications to share data and functionality. For example, OLE objects can be used to embed an Excel spreadsheet into a Word document.
“An attacker who successfully exploited this vulnerability could gain the same user rights as the current user. If the current user is logged on with administrative user rights, an attacker who successfully exploited this vulnerability could take complete control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights,” Microsoft said in its advisory.
Microsoft says it’s aware of limited, targeted attacks in which the vulnerability is exploited through PowerPoint presentations.
The company advises its users to apply a series of workarounds until a permanent patch is made available through the monthly security updates process or an out-of-cycle update. One of the workarounds recommended by Microsoft is an automated “Fix It” solution (OLE packager Shim Workaround) which prevents exploitation of the zero-day flaw.
Microsoft also advises users to ensure that the User Account Control (UAC) feature is enabled since it displays a consent prompt or an elevation prompt before files are run. In the attacks observed by the company, the UAC, which is enabled by default on Windows releases starting with Vista, prompted users before the files containing the exploit were executed.
Windows users are also told to avoid opening PowerPoint or other types of files received from untrusted sources.
“In a web-based attack scenario, an attacker could host a website that contains a webpage that contains a specially crafted Office file that is used to attempt to exploit this vulnerability. In all cases, however, an attacker would have no way to force users to visit these websites. Instead, an attacker would have to convince users to visit the website, typically by getting them to click a link in an email message or Instant Messenger message that takes users to the attacker’s website,” Microsoft clarified.
Protection against these attacks is also provided by the Attack Surface Reduction feature included in Microsoft’s Enhanced Mitigation Experience Toolkit (EMET) 5.0.
CVE-2014-6352 is not the only Microsoft Windows zero-day exploited in targeted attacks over the past period. Earlier this month, iSIGHT Partners reported seeing attacks by a group called the “Sandworm Team,” which had been leveraging weaponized PowerPoint documents in attacks against high-profile targets. The PowerPoint files were designed to exploit a different zero-day (CVE-2014-4114) affecting all supported versions of Windows. Microsoft patched the vulnerability this month with the MS14-060 security bulletin.
Trend Micro later determined that the Sandworm Team leveraged the exploit to target SCADA systems.