Date: Fri, 26 Sep 2014 12:26:05 -0600 From: Kurt Seifried <kseifried@...hat.com> To: oss-security@...ts.openwall.com Subject: Re: Re: CVE-2014-6271: remote code execution through bash (3rd vulnerability) On 26/09/14 12:12 PM, Rich Felker wrote: > On Fri, Sep 26, 2014 at 02:06:21PM +0100, Simon McVittie wrote: >>> Tell everyone to stop using setuid/setgid now and forever? > > Yes! > >> Minimizing use of setuid/setgid, and making sure the setuid/setgid >> things are suitably hardened, is a good idea. However, tools for >> controlled privilege escalation (sudo, pkexec, Apache suexec) rely on >> setuid in order to work. There's a reason the feature exists at all. > > These could all be done by having the process with root privileges > inherit them from a daemon parent that already has root, rather than > requiring the kernel to elevate the privileges of a process via the > setuid bit. This inherently eliminates all attacker control of the > process's initial state and limits the input/attack surface to the > communication channel clients have with the daemon (e.g. a single unix > socket). setuid/setgid is not just for root. For example the Postfix server makes use of various groups and setuid/setgid binaries and directories so that there are well defined interfaces between Postfix components that run with different privilege levels. -- Kurt Seifried -- Red Hat -- Product Security -- Cloud PGP A90B F995 7350 148F 66BF 7554 160D 4553 5E26 7993 Download attachment "signature.asc" of type "application/pgp-signature" (820 bytes)
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