Your SharePoint Server is a Prime Ransomware Target: Here’s How to Protect It
For years, Microsoft SharePoint has been the collaborative backbone for countless organizations, serving as a central repository for critical documents, project plans, and sensitive corporate data. But this central role has also painted a target on its back. A troubling new trend has emerged where cybercriminals are no longer just stealing data from SharePoint servers—they are now using them as a direct launchpad for devastating ransomware attacks.
This evolution in attack methods represents a significant threat to any organization relying on on-premises SharePoint deployments. Understanding how these attacks work and what steps you can take to defend your digital assets is more critical than ever.
The New Attack Vector: From Data Theft to Full-Blown Ransomware
Historically, attackers who compromised SharePoint servers focused on espionage and data exfiltration. Now, their strategy has shifted to a more disruptive and immediately profitable model: ransomware.
The attack chain is dangerously straightforward. Cybercriminals are actively scanning the internet for vulnerable, unpatched SharePoint servers. Once a weakness is found, they exploit it to gain initial access. The most common method involves uploading a malicious file, such as a specially crafted ASPX web shell, to a SharePoint document library. This file masquerades as a harmless document but is actually a powerful backdoor.
Once the web shell is uploaded and executed, the attackers have remote control over the server. From there, they can:
- Perform network reconnaissance to map out your infrastructure.
- Escalate their privileges to gain deeper access.
- Deploy ransomware directly onto the SharePoint server, encrypting all stored files and demanding a hefty ransom for their release.
Because SharePoint is often connected to other network drives and systems, a compromise can quickly spread, paralyzing an entire organization’s operations.
Why SharePoint is a Goldmine for Attackers
Attackers are targeting SharePoint for several key reasons. It is often a treasure trove of an organization’s most valuable information, including:
- Financial records and reports
- Intellectual property and trade secrets
- Employee and customer personal data (PII)
- Strategic business plans
By encrypting these files, attackers know they are applying maximum pressure. The disruption to business operations is immediate and severe, making companies more likely to consider paying the ransom. The centralized nature of SharePoint makes it a single point of failure that, if compromised, can bring productivity to a grinding halt.
Actionable Steps to Secure Your SharePoint Environment
Protecting your SharePoint server is not optional—it’s a fundamental security requirement. Complacency is the attacker’s greatest ally. Here are essential, actionable steps you must take to fortify your defenses against this growing threat.
1. Prioritize Immediate Patching
The primary entry point for these attacks is through known vulnerabilities. Ensure your SharePoint servers are always up-to-date with the latest security patches from Microsoft. Establish a robust patch management policy and apply critical updates as soon as they are released. Do not delay.
2. Implement Strict File Upload Policies
By default, SharePoint allows a wide range of file types to be uploaded. You must restrict this. Block potentially dangerous file extensions like .aspx, .asmx, and .config from being uploaded to document libraries. This single step can prevent attackers from easily placing their web shells on your server. Review Microsoft’s guidance on blocked file types and enforce it without exception.
3. Conduct Regular Security Audits
Proactively hunt for misconfigurations and vulnerabilities. A thorough security audit of your SharePoint farm can identify weaknesses before an attacker does. Pay close attention to user permissions, service account privileges, and network configurations.
4. Enforce the Principle of Least Privilege
Ensure that user and service accounts only have the minimum permissions necessary to perform their roles. Avoid using administrator-level accounts for daily operations. By limiting privileges, you can contain the potential damage an attacker can inflict if they manage to compromise an account.
5. Monitor for Suspicious Activity
Implement robust monitoring and logging on your SharePoint servers. Watch for unusual file uploads (especially outside of business hours), unexpected process executions (like PowerShell commands), and large-scale file modification activity. Endpoint Detection and Response (EDR) solutions should be deployed on all servers, as they can often detect and block the malicious behavior associated with ransomware deployment.
6. Maintain and Test Offline Backups
In a worst-case scenario, a reliable backup is your last line of defense. Ensure you have a comprehensive backup strategy that includes regular, immutable, and offline copies of your SharePoint data. Routinely test your restore process to confirm that you can recover quickly and effectively after an attack. A backup you haven’t tested is not a backup you can trust.
The threat landscape is constantly evolving, and attackers will always gravitate toward high-value targets. By treating your SharePoint server as the critical infrastructure it is and implementing these layered security controls, you can significantly reduce your risk and protect your organization’s most vital data from being held for ransom.
Source: https://go.theregister.com/feed/www.theregister.com/2025/07/24/microsoft_sharepoint_ransomware/
