php 5.4
add old repo, ex jesie
deb http://kartolo.sby.datautama.net.id/debian/ jessie main contrib non-free
deb http://kartolo.sby.datautama.net.id/debian-security/ jessie/updates main contrib non-free
deb-src http://kartolo.sby.datautama.net.id/debian/ jessie main contrib non-free
Debian Stretch 9 users: Add Jessie sources apt sources in /etc/apt/sources.list.d/jessie.list:
deb http://httpredir.debian.org/debian jessie main
deb-src http://httpredir.debian.org/debian jessie main
deb http://security.debian.org/ jessie/updates main
deb-src http://security.debian.org/ jessie/updates main
Pin openssl packages to oldstable (Jessie) in /etc/apt/preferences.d/openssl
Package: openssl libssl-dev libssl-doc libcurl4-openssl-dev libcurl3
Pin: release a=oldstable
Pin-Priority: 600
Now you will have apt-get upgrade working as well, along with security updates provided for openssl pinned packages for Jessie lifetime till June 30, 2020.
ref:
securing php:
https://www.cyberciti.biz/faq/hide-php-version-nginx-on-linux-unix-server/