[Bug 1832074] Re: base-files '/etc/update-motd.d/50-motd-news' reports system use to Ubuntu

[Steve Langasek]

This bug report touches on a number of issues, which are variously
'invalid', 'wontfix', or 'opinion'.  Since the bug title appears to
refer to the (incorrect) claim that the update-motd script will expose
information to the server about when users are logging in to the system,
I am closing as invalid.

** Changed in: base-files (Ubuntu)
       Status: New => Invalid

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Title:
  base-files '/etc/update-motd.d/50-motd-news' reports system use to
  Ubuntu

Status in base-files package in Ubuntu:
  Invalid

Bug description:
  System information::

  root at here $ lsb_release -rd
  Description:    Ubuntu 18.04.2 LTS
  Release:        18.04

  root at here$ dpkg -l base-files | tail -1
  ii  base-files     10.1ubuntu2.4 amd64        Debian base system miscellaneous files

  
  What I expect to happen::

  Logins to my machine should not be communicated to anyone else, and
  should not provide anyone else of information about my machine.

  
  What does happen::

  Logins to my machine report that a login occurred, and provide details
  about the installed system, to Ubuntu.

  
  Report::

  I've just upgraded fromt Trusty to Bionic, and found that on login I
  get a message telling me something about Ubuntu's Kubernetes. I don't
  want advertising presented to me when I log in to MY system, so I
  began to investigate where this is happening - assuming that /etc
  /update-motd.d/10-help-text or 00-header had been updated during the
  upgrade and recreated with this content.

  Instead, I discover that there is another script that has been added -
  /etc/update-motd.d/50-motd-news - which adds this junk text to the
  login. Not only that, but the script comminucates with Ubuntu, to
  fetch that information. Not only that, but it provides information
  about the system that is running as part of the request.

  During the upgrade, I was not asked about whether it was ok for the
  system to call home every time I login (or every 12 hours, whichever
  is sooner, but at least a minute after you boot), and it absolutely
  would not be my expectation that this be the default. When I log in to
  my machine, I do not expect that the event would be reported to any
  off-site system, and I suspect that most other users would be
  surprised if not horrified to find that the fact that a system is in
  use was being reported to Ubuntu.

  The service can be disabled by changing a setting in /etc/defaults
  /motd-news from ENABLED=1 to ENABLED=0, but this almost certainly
  should be defaulting to 0 - tracking disabled by default, not tracking
  enabled by default.

  For example, on my system this provides a user agent containing:

  ```
  curl/7.58.0-2ubuntu3.7 Ubuntu/18.04.2/LTS GNU/Linux/4.15.0-50-generic/x86_64 Intel(R)/Xeon(R)/CPU/X5675/@/3.07GHz uptime/580915.35/4598709.84
  ```

  This means that every time the user logs in (or after 12 hours from
  the prior log in, whichever is longer) Ubuntu receives:

  * The IP address of a system that is in use (which might be behind NAT, but it's still a report).
  * The Distribution version details.
  * The Kernel version details
  * The CPU type
  * The uptime

  Knowing where a machine is, that it is active, exactly what type of
  system it is an how often it is restarted, would be an awesome dataset
  for any attacker to obtain - ideally (for them) it tells them the
  location of systems that are alive, how they might be attacked - from
  the distribution version, the kernel and the CPU information, you can
  determine a set of vulnerabilities to attack - and the uptime, which
  will indicate how likely the system is to be patched.

  The only thing that might be worse might be to include a cookie-jar on
  the curl command, which would allow tracking of individual systems,
  rather than aggregating them behind NAT using the IP (although it's
  still possible that the data reported in the user agent may be able to
  make that information individually usable). That said, the root user
  could (unintentionally) enable a cookie jar in their .curlrc and thus
  enable individual system tracking without realising.

  Whilst there may be legitimate reasons for reporting this information
  (say for reporting to the user that their system has updates available
  or that the system is vulnerable!), an advertising tool which reports
  the system's information regularly back to home does not seem
  appropriate for a 'base-files' package.

  The surprise at having my logins recorded on a remote site pales in
  comparison to the horror of recording a database of systems that might
  be abused.

  The Privacy and potential Security concerns of this feature hugely
  outweigh any perceived benefit to the user, and I believe that the
  right course of action is to remove this script entirely from the
  distribution. At the very least the script's operation should default
  to being disabled.

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