For legitimate Windows 7 updates, always use Windows Update, Microsoft Update Catalog, or WSUS. For Vista, migrate or isolate the system — it has been EOL since April 2017 and is unsafe for internet-facing use.
A practical search (using threat intelligence platforms or even Google) for the exact string "windows6.1-kb958-488-v6001-x64.msu" yields: windows6.1-kb958-488-v6001-x64.msu download