unofficial mirror of bug-guix@gnu.org 
 help / color / mirror / code / Atom feed
From: "Ludovic Courtès" <ludo@gnu.org>
To: Maxime Devos <maximedevos@telenet.be>
Cc: 47584@debbugs.gnu.org
Subject: bug#47584: Race condition in ‘copy-account-skeletons’: possible privilege escalation.
Date: Tue, 06 Apr 2021 13:57:08 +0200	[thread overview]
Message-ID: <87v98zmxrf.fsf@gnu.org> (raw)
In-Reply-To: <00621260aa43f1918aaf0f0bb2318bf359b826c3.camel@telenet.be> (Maxime Devos's message of "Tue, 06 Apr 2021 11:56:23 +0200")

Hi Maxime,

Maxime Devos <maximedevos@telenet.be> skribis:

> On Mon, 2021-04-05 at 21:54 +0200, Ludovic Courtès wrote:
>> [...]
>> 
>> OK.  It does mean that the bug is hardly exploitable in practice: you
>> have to be able to log in at all,
> Yes.
>
>>  and if you’re able to log in, you have
>> to log in precisely within the 1s (or less) that follows account
>> creation, which sounds challenging (TCP + SSH connection establishment
>> is likely to take as much time or more,
>
> Is logging in possible when the home directory doesn't exist?

I think so.

> An attacker could copy and paste, or have used a single-character password,
> to save some time.

Hmm yes.  It’s a bit a far-fetched though: the attacker would have
passed the sysadmin the output of the ‘crypt’ procedure, such that the
sysadmin cannot know the password length.

>> Does it warrant as strong messaging as for the recent daemon
>> ‘--keep-failed’ vulnerability?
>
> As it is a one-time chance, with a limited window, and only under specific
> circumstances (creating a new user account), I don't think so.  But I would
> still recommend to upgrade.  Does the blog post have ‘too strong messaging’? 

The blog post and info-guix messages are the highest levels of
visibility we can give, roughly.  So I think we have to think twice
before doing that or truly important issues will eventually go
unnoticed.

The risk with this issue seems much lower than that of the keep-failed
issue, it even looks super low.

WDYT?

Ludo’.




  reply	other threads:[~2021-04-06 11:58 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-03 16:09 bug#47584: Race condition in ‘copy-account-skeletons’: possible privilege escalation Maxime Devos
2021-04-03 16:22 ` Maxime Devos
2021-04-03 16:32   ` Maxime Devos
2021-04-03 20:15   ` Ludovic Courtès
2021-04-03 16:26 ` Maxime Devos
2021-04-03 20:45   ` Ludovic Courtès
2021-04-03 20:49   ` Ludovic Courtès
2021-04-04 13:29   ` Maxime Devos
2021-04-03 20:27 ` Ludovic Courtès
2021-04-03 20:33 ` Ludovic Courtès
2021-04-04  7:36   ` Maxime Devos
2021-04-05 19:54     ` Ludovic Courtès
2021-04-06  9:56       ` Maxime Devos
2021-04-06 11:57         ` Ludovic Courtès [this message]
2021-04-07 18:28           ` Maxime Devos
2022-10-21  9:31 ` Maxime Devos
2022-10-28 16:03 ` bug#47584: [DRAFT PATCH v2 0/4] Fix race condition in mkdir-p/perms Maxime Devos
2022-10-28 16:04 ` bug#47584: [PATCH 1/3] guile-next: Update to 3.0.8-793fb46 Maxime Devos
2022-10-28 16:04   ` bug#47584: [PATCH 2/3] WIP gnu: Change the Guile used for activation to one that has 'openat' Maxime Devos
2022-10-28 16:04   ` bug#47584: [PATCH 3/3] activation: Fix TOCTTOU in mkdir-p/perms Maxime Devos
2022-10-28 16:05   ` bug#47584: [PATCH 1/3] guile-next: Update to 3.0.8-793fb46 Maxime Devos

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

  List information: https://guix.gnu.org/

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=87v98zmxrf.fsf@gnu.org \
    --to=ludo@gnu.org \
    --cc=47584@debbugs.gnu.org \
    --cc=maximedevos@telenet.be \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
Code repositories for project(s) associated with this public inbox

	https://git.savannah.gnu.org/cgit/guix.git

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).