Hello.
I think that the default Firefox profile can be made more restrictive,
stricter. It's pretty simple and can be done by removing a few default
rules (mentioned in bug report by Vlad K., for example) etc. Anyway,
here are some ideas (based on testing made in the past).
As an example, we can specify, mentions the rules that makes browsing
directories works. My tests made in the past, showed that Firefox needs
an access only to '/dev/' directory - not the whole and everything in
'/**/' folders! The same thing with rules providing an access to
documentation and other files (default rule: '/usr/** r,'). In my
testings, Firefox needed an access to '/usr/share/{glib-2.0,hunspell}/'
folders only! Not everything under '/usr/'.
If it's about '/etc/apparmor.d/abstractions/ubuntu-browsers.d/user-
files' file and rules to access everything in User home folder: by
default, Firefox profile contains rules that allows downloads to
'~/Downloads' and uploads from '~/Public' folders, right? Because, there
is also one rule related to the 'user-files' file: '<abstractions
/ubuntu-browsers.d/firefox>' an access is unrestricted.
Changing/removing rules in the 'user-files' file and adding rules that
allows User to save files only in '~/Downloads' folder seems to fix such
issue - unrestricted access etc. The same thing with unnecessary - in my
opinion - rules mentioned above '/**/' and '/usr' and so on.
Additionally, there can be added a '<private-files-strict>' rule to deny
access to sensitive files and to provide a special attention to
(potentially) executable files. (However, during testings appeared a few
"DENIED" entries in the logs files and additional rules were needed.)
And that's not everything. For example, Users who don't use printers
doesn't need '<abstractions/cups_*>' rule, right? There are many rules
in default Firefox profile that can be changed/removed etc. (Personally,
I'm using profile created from scratch, with more stricter policy).
By the way: it seems that with every next Firefox release, a new rules
needs to be added. It's happens very often. The latest Firefox version,
caused several problems: no menu bar, main window resize, errors with
tab, no website could be enabled by clicking on a bookmarks labels etc.
Really, the v60 version caused many issues, that required a few new
rules. Here are bug report:
● https://bugs.launchpad.net/ubuntu/+source/firefox/+bug/1770600
I hope, that it will help someone to fix problems, that may appear after
Firefox upgrade to the 60.0 version.
Thanks, best regards.
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You received this bug notification because you are a member of Desktop
Packages, which is subscribed to firefox in Ubuntu.
https://bugs.launchpad.net/bugs/1662501
Title:
since the apparmor profile is disabled by default, please make the
apparmor policy strict with option to make less strict
Status in firefox package in Ubuntu:
Triaged
Bug description:
The default Firefox AppArmor profile (package: firefox) allows read
access to all files in the system:
# in /etc/apparmor.d/usr.bin.firefox:
/**/ r
This allows browsing all directory contents on the system which
violates Least Privilege Principle and allows malware to explore
what's on the system (even though there are additional deny rules that
protect most sensitive files, a default read all is still
unacceptable).
In addition (package: apparmor) :
# in /etc/apparmor.d/abstractions/ubuntu-browsers.d/user-files:
@{HOME}/** r,
owner @{HOME}/** w,
Which allows read write to ALL USER FILES, and read to ALL OTHER USER
FILES because default chmod on user dirs is o+rx. Granted, access to
~/.ssh is explicitly denied, but there are things like documents and
other user files that should NOT be readable to Firefox at all.
This is, IMHO, a vulnerability.
The profile should allow read/write ONLY to dirs like ~/Downloads or
~/Public. In addition the above two lines that allow unconfined rw
access to HOME/**, should be commented out and explained what it means
to enable them if the user really wants that kind of convenience.
Modern malware is not just about code execution and modifying local or
system files. Modern malware is also very much so about data and
identity theft against which the current default AppArmor profile does
NOT protect.
Take for example password managers like KeePassX. The default profile
on ubuntu-browsers would allow unfettered access to the very much
sensitive passwords database.
Sure, users can override and expand the profile with their local
modifications, but this "vulnerability" is not documented or
communicated to users and gives a false sense of security ("Oh, I have
AppArmor profile on Firefox, I'm safe").
Unfortunately, proper security is not in the domain of casual computer
usage and I understand that Ubuntu has to balance between convenience
and security but IMHO it is possible to make this more secure AND at
the same time inform the user where to DISABLE (rather than enable)
those stricter rules.
If Ubuntu is not willing to sacrifice the convenience for PROPER
security (shame on Ubuntu if that's the case), then AT THE VERY LEAST
the user should be informed that the default AppArmor profile, when
they install a browser, is biased toward convenience and users SHOULD
take additional actions to protect themselves.
I'm sure this all applies to more than just the browsers, but browsers
are my primary concern here, which are the most vulnerable component
in a modern system.
To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/firefox/+bug/1662501/+subscriptions
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