Urgent Security Alert: Critical Vulnerabilities in Microsoft SharePoint Require Immediate Patching
System administrators and security teams are on high alert as critical vulnerabilities have been identified in multiple versions of Microsoft SharePoint Server. These security flaws are not just theoretical; they are actively being exploited by attackers in the wild, making it imperative for organizations to take immediate action.
Microsoft has released emergency security updates to address these vulnerabilities. If your organization uses an on-premises SharePoint Server, applying these patches should be your top priority to prevent a potentially devastating security breach.
Understanding the Threat: Remote Code Execution
The most severe of these vulnerabilities allows for Remote Code Execution (RCE). In simple terms, this means a remote attacker, without needing to be authenticated, could run malicious code on your SharePoint server.
What does this mean for your business? A successful RCE attack could grant an intruder:
- Complete control over the SharePoint server.
- The ability to view, alter, or delete sensitive company data.
- A foothold to move deeper into your corporate network and compromise other systems.
- The power to install ransomware, spyware, or other malware.
This type of vulnerability represents a worst-case scenario for server security, as it can lead to a full-scale data breach and significant operational disruption.
Who Is at Risk? Identifying Affected SharePoint Versions
This threat specifically targets organizations running their own instances of SharePoint Server. The emergency patches address vulnerabilities in the following versions:
- Microsoft SharePoint Server 2016
- Microsoft SharePoint Server 2019
- Microsoft SharePoint Server Subscription Edition
It is crucial to note that SharePoint Online, part of the Microsoft 365 ecosystem, is not affected by these specific vulnerabilities. Microsoft manages the security and patching for its cloud services directly, highlighting a key security advantage of the cloud-based platform. If your organization is on a legacy or unsupported version of SharePoint, you are highly exposed and should prioritize upgrading immediately.
Your Immediate Action Plan: How to Secure Your Servers
Time is of the essence. Attackers are actively scanning the internet for unpatched servers to exploit. Follow these steps without delay to protect your environment.
1. Apply the Emergency Security Patches Immediately
This is the single most important step. Download the appropriate cumulative update (CU) and security update (SU) for your version of SharePoint Server from the official Microsoft channels. Do not wait for your next scheduled maintenance window. The risk of remaining unpatched is too high.
2. Verify Patch Installation and Server Health
After deploying the updates, it is essential to verify that the installation was successful. Check the patch status in your Central Administration panel and review server health reports. Ensure all SharePoint services restart correctly and that site functionality is unimpeded.
3. Hunt for Signs of Prior Compromise
Because these vulnerabilities were exploited before patches were widely available, you must assume your server may have already been compromised. Patching a server does not remove an attacker who has already gained access.
Security teams should immediately begin threat-hunting activities. Scrutinize server logs for unusual activity, look for unexpected PowerShell execution, check for newly created suspicious user accounts, and scan for any strange files or processes running on the server.
Beyond the Patch: Proactive SharePoint Security Best Practices
While immediate patching is critical, this incident serves as a stark reminder of the need for a robust, ongoing security posture.
- Implement a Strict Patching Cadence: Don’t let security updates fall behind. Establish a reliable process for testing and deploying Microsoft’s monthly security patches to stay ahead of threats.
- Enforce the Principle of Least Privilege: Ensure that service accounts and user accounts only have the permissions absolutely necessary to perform their roles. This can limit an attacker’s ability to move laterally even if they breach the initial server.
- Monitor and Audit Constantly: Use security information and event management (SIEM) tools to actively monitor server logs for anomalous behavior. Early detection is key to mitigating damage.
- Strengthen Network Defenses: Restrict administrative access to your SharePoint servers. Place them behind a properly configured web application firewall (WAF) to filter malicious traffic before it ever reaches the server.
The threat to unpatched SharePoint servers is real, active, and severe. Protecting your organization’s data and infrastructure requires swift and decisive action. Update your systems now.
Source: https://www.bleepingcomputer.com/news/microsoft/microsoft-releases-emergency-patches-for-sharepoint-rce-flaws-exploited-in-attacks/
