Microsoft released update patch KB4487345 for affected Windows 7 SP1 and Windows Server 2008 R2 on 12 January 2019, in order to fix the SMB network share issue caused by security updates KB4480970 (Monthly Rollup) and KB4480960 (Security only) on January 8, 2018.
This update resolves the issue where local users who are part of the local “Administrators“ group may not be able to remotely access shares on Windows 7 SP1 and Windows Server 2008 R2 machines after installing the January 8th, 2019 security updates. This does not affect domain accounts in the local “Administrators” group.
This update fix can be downloaded as standalone update from Microsoft Update Catalog and must be installed manually.