Microsoft today rolled out 53 security patches for the month of November as part of its regular Patch Tuesday update. One of the fixes addresses CVE-2017-11882, a flaw that has existed, unnoticed, in Microsoft Word for the past 17 years.
The fixes announced today address flaws in Windows, Internet Explorer, Office, Edge, ASP.NET Core, .NET Core, and Chakra Core. Twenty of the CVEs are labeled Critical, 30 are ranked Important, and three are Moderate. Three of the bugs today are publicly known but none are categorized as being under active attack, and there were no zero-days this month.
Researchers at Embedi, a firm specializing in security for embedded devices, today released a report on a 17-year-old remote code execution vulnerability in Microsoft Office, which was patched today. They claim it has not been patched and Microsoft did not know it existed.
CVE-2017-11882 is a Microsoft Office Memory Corruption Vulnerability, Microsoft reports. It exists in Office software when the software doesn't properly handle objects in memory. If successfully exploited, it could let an attacker run arbitrary code in the context of the user.
If a user has administrative privileges, an attacker who took advantage of this exploit could take control of an infected system and install programs, view and edit data, or create new accounts with full user rights. Microsoft says this CVE is more dangerous for administrative users.
CVE-2017-11882 could be exploited with a phishing attack; victims need only to open a malicious file with an affected version of Microsoft Office or Microsoft WordPad. In a web-based attack, an attacker could host a website with a malicious file designed to exploit the CVE.
The exploit was created by Embedi experts, who report it works with all Microsoft Office versions released in the past 17 years, including Office 365. It works on versions of Microsoft Windows, including the Creators Update, and it's relevant for all types of architecture. This flaw doesn't interrupt a user's work within Microsoft Office, Embedi explains. Once the document is opened, it doesn't require any further user interaction.
"The only hindrance here is the protected view mode because it forbids content execution (OLE/ActiveX/Macro)," researchers say. However, this could be bypassed with social engineering. An attacker could, for example, ask a user to save a file to the cloud using OneDrive or Google Drive. When opened, protected view mode would not be enabled.
Embedi researchers reported the vulnerability to Microsoft in March 2017 and the final fix was issued today.
Greg Wiseman, senior security researcher at Rapid7, points out CVE-2017-11882 as one of the flaws which could be especially dangerous.
"No non-browser vulnerabilities are considered critical this month, but with a little bit of social engineering, an attacker could theoretically combine one of the Office-based RCE vulnerabilities like CVE-2017-11878 or CVE-2017-11882 with a Windows Kernel privilege escalation weakness such as CVE-2017-11847 to gain complete control over a system," he says.
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