November 12, 2019
Microsoft Office Online is prone to a security vulnerability that may allow attackers to conduct spoofing attacks. An attacker can exploit this issue to conduct spoofing attacks and perform unauthorized actions; other attacks are also possible.
- Microsoft Office Online Server
Run all software as a nonprivileged user with minimal access rights.
To reduce the impact of latent vulnerabilities, always run nonadministrative software as an unprivileged user with minimal access rights.
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.
Do not follow links provided by unknown or untrusted sources.
Never follow links provided by unknown or untrusted sources.
Set web browser security to disable the execution of script code or active content.
Since a successful exploit of this issue allows malicious code to execute in web clients, consider disabling support for script code and active content within the client browser. Note that this mitigation tactic might adversely affect legitimate websites that rely on the execution of browser-based script code.
Updates are available. Please see the references or vendor advisory for more information.
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