From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christian Rebischke Subject: Re: signed tarballs Date: Thu, 13 Apr 2017 23:22:03 +0200 Message-ID: <20170413212203.GB19785@motoko> References: <20170406233134.GA32113@motoko> <3197080.UOV2hoHuAT@x2> <20170411104403.GB386@motoko> <1591540.lCI4k97X9x@x2> <20170413202811.GA18419@motoko> <20170413205649.GA19785@motoko> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============0506992514641335338==" Return-path: Received: from mx1.redhat.com (ext-mx02.extmail.prod.ext.phx2.redhat.com [10.5.110.26]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 335FB5C3FD for ; Thu, 13 Apr 2017 21:22:10 +0000 (UTC) Received: from mout02.posteo.de (mout02.posteo.de [185.67.36.142]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id AC1567D0CA for ; Thu, 13 Apr 2017 21:22:08 +0000 (UTC) In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-audit-bounces@redhat.com Errors-To: linux-audit-bounces@redhat.com To: Paul Moore Cc: linux-audit@redhat.com List-Id: linux-audit@redhat.com --===============0506992514641335338== Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="kORqDWCi7qDJ0mEj" Content-Disposition: inline --kORqDWCi7qDJ0mEj Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Thu, Apr 13, 2017 at 05:05:36PM -0400, Paul Moore wrote: > Unless Steve has exclusive administrative access to people.redhat.com > (I think it is safe to say he does not, but correct me if I'm wrong > Steve ) you can't trust an unsigned checksum regardless of how > strong the https cert/crypto as the web admin could still tamper with > the data. We are not only talking about the web admin. We live in times where governments can easily tamper such data and the documents from snowden and some other whistleblowers prove that they did stuff like this. The only way to make sure that the tarball is the original tarball is with a signature from Steve grubbs gpg-key. This would ensure that steve has checked the content. Just imagine the following scenario: 1. New audit version 2. Steve uploads the new version with new hash to the webserver. 3. Let's imagine that hackers would MITM my connection or modify the server content. They could deploy a new tarball and generate a new checksum for it, because SHA256 is just *one* factor. Everyone who would download the new tarball would check against the new malicious hash. This is a valid attack scenario.. This scenario could only be prevent by using signed tarballs. Because people like me and other distribution maintainers would have Steves pubkey. If somebody would modify the tarball he would need Steves pubkey. And this is much more difficult than just MITM the connection or tampering the data on the webserver. With a signed tarball the attacker would have following problems: 1. the attacker can't deploy a malicious tarball without signature, because this would make clear that the tarball is malicious. 2. if the attacker would generate an own signature for the maliciois tarball, people who verify the tarball would get a warning because the key is unknown and not part of steves keyring. I hope this email is clearer... Thanks for reading. --kORqDWCi7qDJ0mEj Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCgAdFiEEba97gI+d8lE5YgAA0hRh49/iBg0FAljv6/sACgkQ0hRh49/i Bg2n9BAAgeI90urXwRCCNXslGMZR9/lV6Xr2pwANSfi4M9et+Zg5q+PQAg0ieXlG KwpFDWGuQezA9AyAVjVYmXJIbZEn16XMCL/F/LhhxED26KCR90TxtagAi+pcGj3o uzB5a+s7lP97AKF8hlyHwcltl6GmQ36CxUsf5Pc+5I2z1sUoGEVD6hp481/7MdIG OA6xipTg4m8OnXbNjDCH+KvCDBTzSb0w8F/nlXkXLPJ/H4qENYRrX5AXh20mo1UY iWBcuZfzHaCtwPZqqFjuPQXjdz31xKltllh7OvsSWb7alUIfAqp4b2teOv8r8fOt fD2RN9tZyR9iVf+tDOydk5ZA371D5a0y6+AqyyhdrlN4Yoid2ej/XsDw7Me4pPwh 0d6HSfEuyvIwSrkXX967bnoGbUP/4HmvHRku5TZiOw8D3CNxndF15HU8vab0h0yM 9XhzUmGwf+4S9e6l8kVZqP4fcIhVSiY1u594BYmaBe+cXYhKd9p8HzQpFrae8FlA CdaG7Mf96fpwqY1XywNyLbXKhJ4zWZ7gmYiHDPXziCU/kpbs34lu63bTv10yClu6 UzehyHM4RREP3KU8nBL2hXjb9aZw1VF+l0POdUP7S3lEghbAR9V4Zh6+4cZlcbwL 2AQd4iywcVgHmORG3aPohxqRvWVNgjBSzbtsvfxZRkPQ8G7L/d8= =xa6S -----END PGP SIGNATURE----- --kORqDWCi7qDJ0mEj-- --===============0506992514641335338== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline --===============0506992514641335338==--