On 12 August 2015 at 09:33, Reindl Harald h.reindl@thelounge.net wrote:
Am 12.08.2015 um 02:42 schrieb Thomas Daede:
*if* you use binary tarballs they *should not* be extracted in a user writeable location as *no binary* whenever possible should have permissions allowing a ordinary user to change them
This is simply not the way how end users install original Mozilla Firefox binaries.
In addition, if you have write access to ~/, you can also change .bashrc to add paths to executable files and do all sorts of other nasty things
that's why chattr exists
chattr +i ~/.bashrc chattr +i ~/.bash_profile
[root@rh:~]$ touch /home/harry/.bashrc touch: cannot touch '/home/harry/.bashrc': Permission denied
However a compromised application that can write files can probably make executable and fork too. So while immutable provides limited protection, if the real attack surface is the web browser and the worry is privilege escalation then overwriting .bashrc is a side show. Having to run the browser as root to update it (which would remove most of the advantage of automated updates by the mozilla binary) replaces exposing user privileges with exposing root privileges. If you really wanted to be paranoid about this you'd make a separate user account with write permission for that binary to be used for updates. (Which is one of the reasons package managers are a good idea.)