CVE-2024-38094: SharePoint RCE Exploited in the Wild — Patch Now

The Cybersecurity and Infrastructure Security Agency (CISA) has added a significant vulnerability in Microsoft SharePoint Server to its Known Exploited Vulnerabilities (KEV) catalog. According to SecurityWeek, the CVE identified as CVE-2024-38094 is currently being leveraged by adversaries in the wild to achieve RCE. This vulnerability stems from the deserialization of untrusted data, a common weakness that allows an attacker to execute arbitrary code within the context of the SharePoint service.

While the flaw carries a CVSS score of 7.2, its inclusion in the KEV catalog signifies that its real-world impact is substantial. The vulnerability requires the attacker to have at least Site Owner permissions, which initially suggested a limited attack surface. However, threat actors often obtain these credentials through Phishing or by exploiting other misconfigurations, making this a potent tool for escalation within a target environment.

Technical Analysis of CVE-2024-38094

The vulnerability exists in how SharePoint Server handles specifically crafted API requests. When the server processes an object that has been serialized, it fails to properly validate the input before reconstructing the object in memory. By injecting a malicious payload into the serialized data, an authenticated user with sufficient privileges can trigger the execution of code on the underlying server. This type of exploit is particularly dangerous because it bypasses traditional application-level security controls once the initial authentication hurdle is cleared.

From an operational perspective, an APT group can use this vulnerability to establish a persistent foothold. Once RCE is achieved, the attacker typically attempts Lateral Movement to access sensitive databases or domain controllers. In many observed cases, such entry points serve as the precursor to deploying Ransomware or exfiltrating high-value intellectual property.

How to Detect CVE-2024-38094 Exploit Activity

Security teams should focus on identifying anomalous behavior within their SharePoint logs and IIS traffic. To understand how to detect CVE-2024-38094 exploit attempts, analysts should monitor for unusual POST requests to SharePoint API endpoints that involve large or obfuscated serialized objects. Specifically, look for unexpected processes spawning from w3wp.exe (the IIS worker process), such as cmd.exe or powershell.exe, which are hallmarks of a successful RCE.

Detection strategies should also be mapped to the MITRE ATT&CK framework, specifically focusing on T1059 (Command and Scripting Interpreter) and T1190 (Exploit Public-Facing Application). Organizations utilizing a SIEM should correlate SharePoint audit logs with network traffic to identify suspicious C2 communication originating from the SharePoint application tier.

Remediate SharePoint Remote Code Execution and Implementation

The primary method to mitigate this threat is the application of the official security updates released by Microsoft. Following the Microsoft SharePoint Server patch guidance, administrators must ensure that SharePoint Server 2016, 2019, and Subscription Edition are updated to the versions released in July 2024 or later.

In addition to patching, the SOC should implement the following defensive measures:

• Principle of Least Privilege: Audit SharePoint Site Owner and Site Collection Administrator roles to ensure only necessary personnel have elevated permissions.
• Network Segmentation: Isolate SharePoint servers from the broader internal network and limit their ability to initiate outbound connections to the internet.
• Web Application Firewall (WAF): Deploy WAF rules specifically designed to inspect and block malicious serialized payloads in HTTP traffic.

Given that CISA has mandated federal agencies to patch this vulnerability, private sector organizations should treat this as a high-priority remediation task to prevent potential compromise by sophisticated threat actors.