There was a shift years ago from the old help system that has it’s roots going back to Windows 3.0, and was certainly one of the killer features of Windows 3.0, the hyperlinked and searchable help files. They were a form of compiled RTF files, and could also embed image resources, and later audio & video with the evolution of Windows. This allowed for a platform for early multimedia encylopedias and other refrence books of sorts.
Starting with Windows Vista, however the WinHelp engine was being retired out for a CHM or compiled HTML help engine. And for a whlie there optional updates and later downloads to re-enable WinHelp. However starting with Windows 10 the downloads no longer work.
All is not lost however, if you copy any of the 32bit WinHelp programs from NT 3.1 onward it will still function on Windows 10. And thanks to this great post on TenForums, you can re-enable the hook so that Windows 10 will integrate again with WinHelp.
takeown /f "%windir%\winhlp32.exe" >nul
icacls "%windir%\winhlp32.exe" /grant *S-1-5-32-544:F >nul
copy /y "%crtpth%\winhlp32.exe" %windir%
icacls "%windir%\winhlp32.exe" /setowner "NT Service\TrustedInstaller" >nul
echo Press any key to Exit
And there we go, now I can load obsolete refrence docs from great old programs like Visual C++ 1.10 for Windows NT!
Naturally Microsoft removed all this stuff as it was a security risk, in that they apparently never revamped or updated it, so yeah it may be another infection vector.