Hello Stefan,
I patched the SharePoint 2013 farm with March 2018 CU by downloading the package from official Microsoft download site
KB4018302
After the installation and PSConfig was successful when I go to Manage Servers in farm page or check the version through powershell it shows me
Configuration database version: 15.0.5009.1000
Whereas as per the MS article @ https://support.microsoft.com/en-us/help/4018302/march-13-2018-cumulative-update-for-sharepoint-enterprise-server-2013 it should have been 15.0.5015.1002
Please advise what could be the reason.