From owner-freebsd-bugs@freebsd.org Sun Feb 21 17:17:54 2016 Return-Path: Delivered-To: freebsd-bugs@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 72D17AB0427 for ; Sun, 21 Feb 2016 17:17:54 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from kenobi.freebsd.org (kenobi.freebsd.org [IPv6:2001:1900:2254:206a::16:76]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 496CF1517 for ; Sun, 21 Feb 2016 17:17:54 +0000 (UTC) (envelope-from bugzilla-noreply@freebsd.org) Received: from bugs.freebsd.org ([127.0.1.118]) by kenobi.freebsd.org (8.15.2/8.15.2) with ESMTP id u1LHHsFp074303 for ; Sun, 21 Feb 2016 17:17:54 GMT (envelope-from bugzilla-noreply@freebsd.org) From: bugzilla-noreply@freebsd.org To: freebsd-bugs@FreeBSD.org Subject: [Bug 207396] Crafted tar archive can be used to remove arbitrary files Date: Sun, 21 Feb 2016 17:17:54 +0000 X-Bugzilla-Reason: AssignedTo X-Bugzilla-Type: new X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: Base System X-Bugzilla-Component: misc X-Bugzilla-Version: 10.2-RELEASE X-Bugzilla-Keywords: X-Bugzilla-Severity: Affects Only Me X-Bugzilla-Who: fuz@fuz.su X-Bugzilla-Status: New X-Bugzilla-Resolution: X-Bugzilla-Priority: --- X-Bugzilla-Assigned-To: freebsd-bugs@FreeBSD.org X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: bug_id short_desc product version rep_platform op_sys bug_status bug_severity priority component assigned_to reporter attachments.created Message-ID: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: https://bugs.freebsd.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-BeenThere: freebsd-bugs@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: Bug reports List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 21 Feb 2016 17:17:54 -0000 https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D207396 Bug ID: 207396 Summary: Crafted tar archive can be used to remove arbitrary files Product: Base System Version: 10.2-RELEASE Hardware: Any OS: Any Status: New Severity: Affects Only Me Priority: --- Component: misc Assignee: freebsd-bugs@FreeBSD.org Reporter: fuz@fuz.su Created attachment 167263 --> https://bugs.freebsd.org/bugzilla/attachment.cgi?id=3D167263&action= =3Dedit A tar file that removes a file named f1 in badly constructed tar implementations The ustar file format allows to store hard links. Hard links are stored as entries with file type 1 and the linkname field set to the file to link to.= In badly constructed tar implementations, a crafted tar file that attempts to = link a file to itself can be used to remove files as the tar program first check= s if the link-target exists, then unlinks the file name to be linked to and fina= lly attempts to create a link to a non-existent file, which fails for obvious reasons. This attack vector has been known since at least 2003 and is part = of the star test suite. FreeBSD tar apparently doesn't contain code to catch this scenario. Instead= , it happily deletes files using such crafted archives. This is a potential secu= rity problem as tar is not expected to delete files without replacement as it unpacks an archive. Attached is the relevant test case from the star test suite. --=20 You are receiving this mail because: You are the assignee for the bug.=