Can Chromium Browser's Permissions Facilitate a Root Kit Exploit?

Question

I'm just learning about permissions and excuse me if I may have gone astray. But, I've noticed that Chromium Browser has a sandbox executable that is owned by root and has it's user id set to launch as root.

manager@internet /usr/lib/chromium-browser $ ls -l
total 63836
-rw-r--r-- 1 root root  3093552 2012-02-21 01:41 chrome.pak
-rwxr-xr-x 1 root root 56785884 2012-02-21 02:09 chromium-browser
-rwsr-xr-x 1 root root    13636 2012-02-21 02:09 chromium-browser-sandbox
-rw-r--r-- 1 root root       15 2012-02-21 01:36 content_resources.pak
-rw-r--r-- 1 root root  1629044 2012-02-21 02:09 libffmpegsumo.so
drwxr-xr-x 2 root root     1160 2012-02-28 07:30 locales
drwxr-xr-x 2 root root       40 2012-02-21 02:05 plugins
-rw-r--r-- 1 root root  3669791 2012-02-21 01:42 resources.pak
-rwxr-xr-x 1 root root    37394 2012-02-15 15:35 xdg-mime
-rwxr-xr-x 1 root root    33273 2012-02-15 15:35 xdg-settings

It is my understanding this is a dangerous situation. Is it not possible this may lead to an exploit as a root kit? Why should a browser be launching with root id?

Answer 1

Ironically, I think this is so that it can be more secure : see http://code.google.com/p/chromium/wiki/LinuxSUIDSandbox

The sandbox helper binary creates new restricted processes to run the sandboxed components like Flash or other binary plugins.

The practical upshot is that without SUID, the sandbox helper binary can't:

• chroot to another part of the filesystem to restrict access to the real file system.
• Create a new PID namespace to prevent sandboxed components tracing or killing other processes

Both of these operations require a privileged process.