WINDOWS EXPLOITATION TECHNIQUES: DANGLING COM OBJECT REGISTRATIONS

Summary from the TLDR InfoSec newsletter

A Windows COM class stayed registered to a missing DLL in the user-writable ProgramData folder, letting any user plant code for a SYSTEM process to load (CVE-2026-66804, an incomplete fix for "Dark Elevator"). The exploit sent a custom-marshaled object pointing to the dangling CLSID to the Shell Create Object Handler, a SYSTEM COM server that ordinary users can start via a scheduled task and that allows custom marshaling. Defenders should patch, audit InProcServer32 registrations for DLLs that don't resolve in writable paths, and make sure privileged COM servers set EOAC_NO_CUSTOM_MARSHAL or the strong unmarshaling policy.