SharePoint CVE-2026-65660 ExpandedWrapper/LosFormatter Deserialization Payload

This rule detects malicious deserialization attempts targeting Microsoft SharePoint, specifically leveraging System.Data.Services.Internal.ExpandedWrapper combined with LosFormatter and System.Xaml.XamlServices. This signature is indicative of exploitation attempts related to CVE-2026-65660, allowing an attacker to achieve remote code execution by bypassing SafeControls restrictions.