Microsoft Excel CVE-2017-11877 Security Bypass Vulnerability

Description

Microsoft Excel is prone to a security-bypass vulnerability. An attacker can leverage this issue to bypass certain security restrictions and execute arbitrary code by exploiting another vulnerability in the application.

Technologies Affected

• Microsoft Excel 2007 SP3
• Microsoft Excel 2010 Service Pack 2 (32-bit editions)
• Microsoft Excel 2010 Service Pack 2 (64-bit editions)
• Microsoft Excel 2013 RT Service Pack 1
• Microsoft Excel 2013 Service Pack 1 (32-bit editions)
• Microsoft Excel 2013 Service Pack 1 (64-bit editions)
• Microsoft Excel 2016 (32-bit editions)
• Microsoft Excel 2016 (64-bit editions)
• Microsoft Excel 2016 for Mac
• Microsoft Excel Viewer 2007 Service Pack 3

Recommendations

Block external access at the network boundary, unless external parties require service.
If global access isn’t needed, filter access to the affected computer at the network boundary. Restricting access to only trusted computers and networks might greatly reduce the likelihood of exploits.

Run all software as a nonprivileged user with minimal access rights.
To reduce the impact of latent vulnerabilities, run the application with the minimal amount of privileges required for functionality.

Deploy network intrusion detection systems to monitor network traffic for malicious activity.
Deploy NIDS to monitor network traffic for signs of anomalous or suspicious activity. This includes but is not limited to unexplained incoming and outgoing traffic. This may indicate exploit attempts or activity that results from successful exploits.

Implement multiple redundant layers of security.
Various memory-protection schemes (such as nonexecutable and randomly mapped memory segments) may hinder an attacker’s ability to exploit this vulnerability to execute arbitrary code.

Updates are available. Please see the references or vendor advisory for more information.