OK, so there is a way to get 7 IS installer:
You need to search pirate software sites for version 7.0.1474. Afted downloading a package with installer, check its signature in file Properties.
MD5 of my file is: avast_internet_security_setup.exe : 6d5751d55673b4bb8753fdf803a39aa5, bytes: 127 444 664
**** you again Avast for making me go to such places, ironically, to enchance my security.