Surge in SharePoint Attacks Linked to Leaked Exploit: How to Protect Your Data
Organizations relying on Microsoft SharePoint are facing a significant threat as cybercriminals actively exploit a critical vulnerability. Security researchers have connected a recent wave of attacks to a leaked proof-of-concept (PoC) exploit that makes it dangerously easy for malicious actors to compromise servers.
This development puts any organization with an unpatched, internet-facing SharePoint server at immediate risk of data breaches, ransomware attacks, and complete system takeover. Understanding the nature of this threat is the first step toward building a robust defense.
The Root of the Problem: A Leaked Proof-of-Concept
The current attacks are largely centered around a vulnerability tracked as CVE-2023-24955, a critical remote code execution (RCE) flaw in Microsoft SharePoint Server. While Microsoft released a patch for this issue months ago, the situation escalated dramatically after a detailed PoC exploit was leaked online.
This leak effectively handed cybercriminals a step-by-step guide to weaponize the vulnerability. The PoC was originally developed by security researchers for legitimate testing purposes, but its public exposure has armed even less-sophisticated attackers with the tools to launch effective campaigns.
The exploit allows an attacker with access to an account with Site Owner privileges to execute arbitrary code on the SharePoint server. This means a threat actor could potentially:
- Steal sensitive corporate data.
- Deploy ransomware to encrypt files.
- Install backdoors for persistent access.
- Use the compromised server as a pivot point to attack other systems on the network.
Who is at Risk?
The vulnerability affects several versions of the on-premise SharePoint platform. Your organization is considered at high risk if you are running:
- Microsoft SharePoint Server 2019
- Microsoft SharePoint Server 2016
- Microsoft SharePoint Server Subscription Edition
Any of these versions that have not been updated with the latest security patches are prime targets. The simplicity of the leaked exploit means that automated scanners are likely sweeping the internet for vulnerable servers right now.
Actionable Security Steps to Protect Your SharePoint Environment
Proactive defense is crucial. If your organization uses an on-premise version of SharePoint, your security team must take immediate action to mitigate this threat. Waiting to be attacked is not a viable strategy.
Here are the essential steps you need to take to secure your systems:
Apply Security Patches Immediately: This is the most critical step. Ensure that the security updates released by Microsoft in May 2023 and subsequent cumulative updates have been installed. Do not delay this process. Verifying that the patch has been successfully applied is just as important as deploying it.
Monitor for Signs of Compromise: Even if you have patched, it’s wise to check for any prior malicious activity. Security teams should look for suspicious processes originating from the SharePoint server’s
w3wp.exeprocess, such as unexpected PowerShell or command prompt executions. Scrutinize server logs for unusual access patterns or commands.Restrict Access and Enforce Least Privilege: Review all user accounts, especially those with Site Owner permissions. Ensure that only a limited number of trusted administrators hold this level of access. Applying the principle of least privilege minimizes the attack surface, making it harder for an attacker to gain the foothold needed to launch the exploit.
Enhance Network Segmentation: Isolate your SharePoint servers from other critical parts of your network. Proper network segmentation can help contain a breach, preventing an attacker from moving laterally from a compromised SharePoint server to other high-value assets like domain controllers or databases.
Audit External-Facing Servers: Pay special attention to any SharePoint servers that are accessible from the internet. These are the most likely targets for opportunistic attackers. Regularly scan them for vulnerabilities and ensure they are hardened according to security best practices.
The ongoing attacks serve as a stark reminder that known vulnerabilities are a favorite target for cybercriminals. By prioritizing immediate patching, vigilant monitoring, and strong access controls, organizations can effectively defend their valuable data and infrastructure from this widespread threat.
Source: https://go.theregister.com/feed/www.theregister.com/2025/07/26/microsoft_sharepoint_attacks_leak/
