From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mp2 ([2001:41d0:2:bcc0::]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) by ms0.migadu.com with LMTPS id AB2YE5UwbGB0iQAAgWs5BA (envelope-from ) for ; Tue, 06 Apr 2021 11:57:41 +0200 Received: from aspmx1.migadu.com ([2001:41d0:2:bcc0::]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) by mp2 with LMTPS id EFN1DpUwbGCKIwAAB5/wlQ (envelope-from ) for ; Tue, 06 Apr 2021 09:57:41 +0000 Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by aspmx1.migadu.com (Postfix) with ESMTPS id 6C08B190B6 for ; Tue, 6 Apr 2021 11:57:40 +0200 (CEST) Received: from localhost ([::1]:32986 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lTiSo-00054F-C3 for larch@yhetil.org; Tue, 06 Apr 2021 05:57:38 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:53580) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lTiSF-00052U-T9 for bug-guix@gnu.org; Tue, 06 Apr 2021 05:57:05 -0400 Received: from debbugs.gnu.org ([209.51.188.43]:55921) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1lTiSE-0005Cj-IA for bug-guix@gnu.org; Tue, 06 Apr 2021 05:57:03 -0400 Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.84_2) (envelope-from ) id 1lTiSE-0003gF-Gn for bug-guix@gnu.org; Tue, 06 Apr 2021 05:57:02 -0400 X-Loop: help-debbugs@gnu.org Subject: bug#47584: Race condition in =?UTF-8?Q?=E2=80=98copy-account-skeletons=E2=80=99:?= possible privilege escalation. Resent-From: Maxime Devos Original-Sender: "Debbugs-submit" Resent-CC: bug-guix@gnu.org Resent-Date: Tue, 06 Apr 2021 09:57:02 +0000 Resent-Message-ID: Resent-Sender: help-debbugs@gnu.org X-GNU-PR-Message: followup 47584 X-GNU-PR-Package: guix X-GNU-PR-Keywords: security patch To: Ludovic =?UTF-8?Q?Court=C3=A8s?= Received: via spool by 47584-submit@debbugs.gnu.org id=B47584.161770300914126 (code B ref 47584); Tue, 06 Apr 2021 09:57:02 +0000 Received: (at 47584) by debbugs.gnu.org; 6 Apr 2021 09:56:49 +0000 Received: from localhost ([127.0.0.1]:39234 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1lTiS1-0003fj-9B for submit@debbugs.gnu.org; Tue, 06 Apr 2021 05:56:49 -0400 Received: from albert.telenet-ops.be ([195.130.137.90]:40674) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1lTiRz-0003fZ-AE for 47584@debbugs.gnu.org; Tue, 06 Apr 2021 05:56:48 -0400 Received: from butterfly.local ([213.119.235.56]) by albert.telenet-ops.be with bizsmtp id pMwk240041Dh5Ut06MwlpH; Tue, 06 Apr 2021 11:56:45 +0200 Message-ID: <00621260aa43f1918aaf0f0bb2318bf359b826c3.camel@telenet.be> From: Maxime Devos Date: Tue, 06 Apr 2021 11:56:23 +0200 In-Reply-To: <87zgycqzfz.fsf@gnu.org> References: <1a6ed722dfdd96dc8d53f939aa8e440ca7c29213.camel@telenet.be> <87mtufw1kh.fsf@gnu.org> <7ab30aad812e5de1216c95b3becb784e3363e615.camel@telenet.be> <87zgycqzfz.fsf@gnu.org> Content-Type: multipart/signed; micalg="pgp-sha512"; protocol="application/pgp-signature"; boundary="=-B/f2LK5SH1auzwQX5K/f" User-Agent: Evolution 3.34.2 MIME-Version: 1.0 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=telenet.be; s=r21; t=1617703005; bh=9PumJZ8JhDKSK4oMiQdzCuIPgUTftNIqOt8tscAGGeQ=; h=Subject:From:To:Cc:Date:In-Reply-To:References; b=Bzjq5aL12xO2hc252nimbtrPuWzGL4wGiz7TycHpIvyo6NP3vNRwYkC3qzGMz39jm QoTW83ROoyn9j2cxIQrIh6AATpyKp5owLMLTpUdXPyqotE8oFtSMXAeZ10DHkq6RIH htFsQ/lkGqtPGhXk9NVPqLzPNbayyyWA1wX+pDfAGbwdOqHuHT+SLfqLqctOFf4GIH tcXGXiqIH/43XP7fX3lc0a5FSuD0xqqcVph4mxjkuG1Ns4EWy6oQuUqiXX/zQPnBnV JoSAkjxINkCcvqoCKj7gJfAFIPqFtS6rrnoMGsisCoTLNpwScS2vrUtIGUQgZOKIZB G76FbH8zf2lAg== X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list X-BeenThere: bug-guix@gnu.org List-Id: Bug reports for GNU Guix List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: 47584@debbugs.gnu.org Errors-To: bug-guix-bounces+larch=yhetil.org@gnu.org Sender: "bug-Guix" X-Migadu-Flow: FLOW_IN ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=yhetil.org; s=key1; t=1617703061; h=from:from:sender:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:resent-cc:resent-from:resent-sender: resent-message-id:in-reply-to:in-reply-to:references:references: list-id:list-help:list-unsubscribe:list-subscribe:list-post: dkim-signature; bh=9PumJZ8JhDKSK4oMiQdzCuIPgUTftNIqOt8tscAGGeQ=; b=blILD6qS/slsnXVhOHPj6tEn/k+6qOfrIcUrLXHAQjnaow+I/yJTjXaJiJoIrVzDkASxvZ 5zSdqv/qnkZ0MSv4DD43v/Dcqj5G/zfcwt5wRgJF7HXTlzwukq1mEDZn201ETwVg5lm+WI 84m9EOJh8RNET66e77+t644FV6iUvBz+X78qKrWwaVlIMhp80Bnz8Z8qlGrth/a7afaDOL HwF/nGWlH5fPq49dHnXowCBNyiAjqwpYteA9rnJ/hk6+0/Xi57pzYkLI3b4QOysld9YX7W 5CoXMJUypqJ1xsT8M3IfwSWDF1pXikuk1mOKQ5p1kO3ADu3uB116UP6+a9cSbQ== ARC-Seal: i=1; s=key1; d=yhetil.org; t=1617703061; a=rsa-sha256; cv=none; b=F0Jn2heWTahbjtKynEZEPEvZh0N5yWzNToCiBLU3wd79WObFUieqE+qy4wslfzcYVwVwgS 6Y0cIhKnDA1VzRKX9PTo2Gf33i4g5mZdYRJIPYy1XdmU+vPDvHZQqDrJFnQIGuJm3NDur7 A8rWQ3TIVpsPVCjhrHd/F+9LcE8j2OkCnhBTZVoGERuFHaUMK9Eh/wALt9VUN8jyd1VKB5 Ob17C1oxmb4AyxWZ2hqBuld7n7pxzUbU+ZInZ17NZmGYFDsHEuSzxAVwJvbjR8+Xmg2LzO Kx8oduE9c6cHO9EgejeKXWxUxUKCbwyMZ+swNQOhvr1uq+mY3GqNjC3by2/Nrg== ARC-Authentication-Results: i=1; aspmx1.migadu.com; dkim=fail ("headers rsa verify failed") header.d=telenet.be header.s=r21 header.b=Bzjq5aL1; dmarc=fail reason="SPF not aligned (relaxed)" header.from=telenet.be (policy=none); spf=pass (aspmx1.migadu.com: domain of bug-guix-bounces@gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=bug-guix-bounces@gnu.org X-Migadu-Spam-Score: -1.94 Authentication-Results: aspmx1.migadu.com; dkim=fail ("headers rsa verify failed") header.d=telenet.be header.s=r21 header.b=Bzjq5aL1; dmarc=fail reason="SPF not aligned (relaxed)" header.from=telenet.be (policy=none); spf=pass (aspmx1.migadu.com: domain of bug-guix-bounces@gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=bug-guix-bounces@gnu.org X-Migadu-Queue-Id: 6C08B190B6 X-Spam-Score: -1.94 X-Migadu-Scanner: scn0.migadu.com X-TUID: x7YM9TVOxS6y --=-B/f2LK5SH1auzwQX5K/f Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Mon, 2021-04-05 at 21:54 +0200, Ludovic Court=C3=A8s wrote: > [...] >=20 > 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=E2=80=99re 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? It isn't possible from the console. I guess it isn't possible from SSH either. If it is possible, then the window would be somewhat larger I think. Account creation is done at activation time, while creating home directories is done as a shepherd service (see account-service-type in gnu/system/shadow.scm). > likewise for typing in your password.) An attacker could copy and paste, or have used a single-character password, to save some time. > It=E2=80=99s also one-time chance. Yes. > Do I get it right? I think so, except the window might be larger (but still a one-time chance)= . > Does it warrant as strong messaging as for the recent daemon > =E2=80=98--keep-failed=E2=80=99 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 =E2=80=98too strong me= ssaging=E2=80=99?=20 Greetings, Maxime --=-B/f2LK5SH1auzwQX5K/f Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- iI0EABYKADUWIQTB8z7iDFKP233XAR9J4+4iGRcl7gUCYGwwRxccbWF4aW1lZGV2 b3NAdGVsZW5ldC5iZQAKCRBJ4+4iGRcl7rX2AP0ak8CCNXY2v2apFETUInxpt8UZ 6E0vkWhJvLARcgTkHwEAnnHFIqZOe+EvFa3Ex3qOefhHRIiwFKE8xB0gCdpZsQQ= =oG1p -----END PGP SIGNATURE----- --=-B/f2LK5SH1auzwQX5K/f--