Rule Document 1:66792

Rule Category

POLICY-OTHER --

Alert Message

POLICY-OTHER Microsoft Sharepoint invalid WS-Trust request

Rule Explanation

This rule looks for authentication requests to Microsoft Sharepoint servers that contains objects that may contain malicious serialized objects.

What To Look For

This rule alerts on traffic to Microsoft Sharepoint endpoints that are vulnerable to an insecure deserialization vulnerability.

Known Usage

No public information

False Positives

Known false positives, with the described conditions

This rule alerts on all traffic that matches the vulnerable authentication pathway regardless of the serialized objects contents.

Contributors

Cisco Talos Intelligence Group

Rule Groups

MITRE::ATT&CK Framework::Enterprise::Initial Access::Exploit Public-Facing Application

Adversaries may attempt to take advantage of a weakness in an Internet-facing computer or program using software, data, or commands in order to cause unintended or unanticipated behavior. The weakness in the system can be a bug, a glitch, or a design vulnerability. These applications are often websites, but can include databases (like SQL), standard services (like SMB or SSH), network device administration and management protocols (like SNMP and Smart Install), and any other applications with Internet accessible open sockets, such as web servers and related services.

CVE

CVE-2026-50522

Additional Links

msrc.microsoft.com/update-guide/vulnerability/CVE-2026-50522

Rule Vulnerability

Insecure Deserialization

Insecure Deserialization relates to web application security. Applications turn an object into data through serialization; the reverse of that process, deserialization, can be vulnerable to attacks when the application trusts the data that is being deserialized. Serialized data is machine readable and not encrypted; serialized user-supplied data should not be trusted. Deserialization attacks can lead to remote code execution.

CVE Additional Information

This product uses data from the NVD API but is not endorsed or certified by the NVD.

CVE-2026-50522

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