asp.net - SSL Certificate issue to the end user -

i have web site developed in asp.net , hosted in cloud. site running on https protocol , certificate issued domain (e.g. example.com ) , subdomain (*.example.com). works if user types example.com or app.example.com. user types url incorrectly. type www.app.example.com. in case browser displays warning certificate. states “this server not prove www.app.example.com; security certificate *.example.com. may caused misconfiguration or attacker intercepting connection”

this fine since subject name (or issued to) not matching since involves 2 subdomains i.e. first subdomain www , subdomain app. many user scare , leave web site. googling found, problem can fixed regenerating certificate additional subject alt names such *.example.com , ..example.com. staff not want regenerate certificate reason. there alternative fix problem without regenerating certificate. expectation error message should not displayed , action should not required end user.

i have tried redirect rules in iis. not working.

platform details – asp.net mvc 5, iis 7.5 , windows server 2008 r2 datacenter

is there alternative fix problem without regenerating certificate.

no. certificate must match name. if certificate not match user gets error. there no way around , if there 1 considered security risk, because without proper name check man-in-the-middle attacks possible.

i have tried redirect rules in iis. not working.

redirects done @ http level, means https first needs establish ssl connections. if fails because of name mismatch redirect not reached.