Date: Thu, 9 Oct 2014 01:05:23 +0200 From: Jann Horn <jann@...jh.net> To: oss-security@...ts.openwall.com Subject: Re: openssh on linux rce in sftp-only mode On Wed, Oct 08, 2014 at 06:44:32PM -0400, Josh Bressers wrote: > > > > > > I think one has to assume if a user has unrestricted sftp access, they can > > > figure out how to do most anything. Even with the upstream hardening patch, > > > it really only protects the sftpd process. Any other processes the user may > > > own could be modified. > > > > Not that easily - /proc/$pid/mem requires you to either be the same process > > or be attached to it via ptrace, I think. > > > > I can't speak for other systems (I don't understand the details), but I can > read arbitrary process memory for processes I own in Fedora 20. Hmm, just tried it on Debian Testing, I can reproduce that. > Does someone know what the typical default is? I looked through the git history of fs/proc/base.c now, looks like commit e268337dfe26dfc7efd422a804dbb27977a3cccc ("proc: clean up and fix /proc/<pid>/mem handling") changed the behavior to be more permissive. That commit is between kernel 3.2 and 3.3. Meh. :( Download attachment "signature.asc" of type "application/pgp-signature" (820 bytes)
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