feat(os-14) add rule to check noexec, nosuid and nodev mount options #164
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cmhe
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controls/os_spec.rb
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| title 'Check mount options (noexec, nodev, nosuid)' | ||
| desc 'Use the noexec, nodev and nosuid mount options to limit attack vectors via mount points' | ||
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| inspec.file('/proc/self/mountinfo').content.split(/\n/).map { |l| l.split[4] }.each do |mnt_point| |
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Its very dangerous to just run over all mounts. Is there a reason why we need this for all? This also makes the logic about blocklist and approvelist more complex. Is there another way to achieve the result?
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Unix systems can mount everywhere, and therefore a static list of mounts might not be enough.
TBH, I currently don't see the danger in iterating over mounted volumes and reporting on their current mount options. Maybe you can elaborate?
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You can run into may issues that are unexpected here. I propose the following:
- We optimize os-14 to cover the matrix that is outlined in https://github.com/CISOfy/lynis/blob/3.0.6/include/tests_filesystems#L562
- I like the ability to test all mountpoints. I discussed with @atomic111 about the approach and we agree that we do not understand the effects on production systems yet. General guidance should be to disallowed mounting for unprivileged users in the first place. And we know a few places where this control would break existing deploys.
Therefore I propose we add a specific control that scans all mount points (minus the one already tested on os-14). That control should be flagged as optional, therefore will not be activated as default yet.
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I removed the dynamic mount check, and now only check the mount points specified.
I haven't found any precedence of optionally flagged controls in dev-sec, how should we go about that?
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You would define an attribute and then add a only_if option if the variable is active
see
https://github.com/dev-sec/cis-docker-benchmark/blob/master/controls/host_configuration.rb#L52-L70 for inspiration
controls/os_spec.rb
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| title 'Check mount options (noexec, nodev, nosuid)' | ||
| desc 'Use the noexec, nodev and nosuid mount options to limit attack vectors via mount points' | ||
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| inspec.file('/proc/self/mountinfo').content.split(/\n/).map { |l| l.split[4] }.each do |mnt_point| |
There was a problem hiding this comment.
You can run into may issues that are unexpected here. I propose the following:
- We optimize os-14 to cover the matrix that is outlined in https://github.com/CISOfy/lynis/blob/3.0.6/include/tests_filesystems#L562
- I like the ability to test all mountpoints. I discussed with @atomic111 about the approach and we agree that we do not understand the effects on production systems yet. General guidance should be to disallowed mounting for unprivileged users in the first place. And we know a few places where this control would break existing deploys.
Therefore I propose we add a specific control that scans all mount points (minus the one already tested on os-14). That control should be flagged as optional, therefore will not be activated as default yet.
Setting the `noexec`, `nosuid` and `nodev` mount options for mount points where those features are not required, limits possible attack vectors. Closes: dev-sec#163 Signed-off-by: Claudius Heine <[email protected]>
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This looks great. Thank you @cmhe |
Setting the
noexec,nosuidandnodevmount options for mountpoints where those features are not required, limits possible attack
vectors.
Closes: #163
Signed-off-by: Claudius Heine [email protected]