bugtraq - Re: /proc filesystem allows bypassing directory permissions on Linux

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20091023220544.GA2521@elf.ucw.cz>
Date: Sat, 24 Oct 2009 00:05:44 +0200
From: Pavel Machek <pavel@....cz>
To: Dan Yefimov <dan@...htwave.net.ru>
Cc: Matthew Bergin <matt.bergin@...mail.com>,
	bugtraq@...urityfocus.com
Subject: Re: /proc filesystem allows bypassing directory permissions on
 Linux

On Sat 2009-10-24 01:12:51, Dan Yefimov wrote:
> On 24.10.2009 0:35, Matthew Bergin wrote:
> >doesnt look like the original owner is trying to write to it. Shows it
> >cant, it had guest write to it via the proc folders bad permissions.
> >Looks legitimate
> >
> Please tell me, who issued 'chmod 0666 unwritable_file'? Was that an
> attacker? No, that was the owner of 'unwritable_file', nobody else.
> What the 0666 file mode means? It means, that everybody can write to
> the file, can't he? So why do you believe that pretension
> legitimate?

Original owner did chmod 666... after making sure traditional unix
permissions protect the file. Please look at original mail; it was
subtle but I believe I got it right, and file would not be writable
with /proc unmounted.

									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html