CVE-2024-21378: 
vulnerability analysis and mitigation

CVE-2024-21378 is a remote code execution vulnerability in Microsoft Outlook discovered in 2023 by NetSPI. The vulnerability was disclosed to Microsoft on September 29, 2023, and a patch was released on February 13, 2024. The vulnerability affects Microsoft Outlook and various Microsoft Office products including Microsoft 365 Apps Enterprise, Office 2019, Office LTSC 2021, and Outlook 2016 (NetSPI Blog).

The vulnerability exists in Outlook's form syncing capability, specifically in how it handles IPM.Microsoft.FolderDesign.FormsDescription objects. The vulnerability allows authenticated users to create arbitrary registry keys under HKCR, place files at arbitrary locations on disk, and create forms that when executed lead to Outlook loading registered COM objects by CLSID. The vulnerability has a CVSS v3.1 base score of 8.8 (HIGH) with vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H (NVD).

When successfully exploited, the vulnerability allows an authenticated attacker to execute arbitrary code through Microsoft Outlook. The attacker could gain the ability to create registry keys, write files to disk, and execute code within the context of the Outlook process (NetSPI Blog).

Microsoft has released security updates to address this vulnerability. Users should apply the latest security patches available through Microsoft Update. The fix was released on February 13, 2024, as part of Microsoft's regular patch cycle (Microsoft Support).