/etc/issue : contains a message or system identification to be printed before the login prompt.
/etc/profile : controls system-wide default variables, such as Export variables, File creation mask (umask), Terminal types, Mail messages to indicate when new mail has arrived
/proc/version : specifies the version of the Linux kernel
/proc/self/environ
/etc/passwd : has all registered user that has access to a system
/etc/shadow : contains information about the system’s users’ passwords
/root/.bash_history : contains the history commands for root user
/var/log/dmessage : contains global system messages, including the messages that are logged during system startup
/var/log/auth.log : contains all ssh logs, (rce and log poisoning)
/var/mail/root : all emails for root user
/home/<user>/.ssh/id_rsa : Private SSH keys for a root or any known valid user on the server
/var/log/apache2/access.log : the accessed requests for Apache web server
/proc/cmdline
/etc/hosts
/etc/issue
C:\boot.ini : contains the boot options for computers with BIOS firmware