Internet Shortcut Shell Extension DLL.
rundll32.exe url.dll,OpenURL "C:\test\calc.url"
Launch an executable payload via proxy through a(n) URL (information) file by calling OpenURL.
Load an executable payload by calling a .url file with or without quotes.
c:\windows\system32\url.dll, c:\windows\syswow64\url.dll
Sigma: https://github.com/SigmaHQ/sigma/blob/62d4fd26b05f4d81973e7c8e80d7c1a0c6a29d0e/rules/windows/process_creation/proc_creation_win_rundll32_susp_activity.yml
Adam (OpenURL) (@hexacorn), Jimmy (OpenURL) (@bohops), Malwrologist (FileProtocolHandler - HTA) (@DissectMalware), r0lan (Obfuscation) (@r0lan)