Date: Wed, 13 Feb 2019 20:57:43 +1100 From: Aleksa Sarai <cyphar@...har.com> To: EJ Campbell <ejc3@...izonmedia.com> Cc: oss-security@...ts.openwall.com Subject: Re: CVE-2019-5736: runc container breakout exploit code On 2019-02-13, Aleksa Sarai <cyphar@...har.com> wrote: > On 2019-02-13, EJ Campbell <ejc3@...izonmedia.com> wrote: > > While fixing docker / runc is clearly the right fix, would using chattr -i > > on runc be a quick mitigation for the issue? I believe that will prevent > > the file from being overwritten by the exploit and Etienne Stalmans > > verified that it helped: > > https://twitter.com/_staaldraad/status/1095354945073754112 > > The privileged user in the container could just un-set the immutable > bit using "/proc/self/fd/..." and then open it for writing. A read-only > filesystem would work much better. Sorry, I forgot that CAP_LINUX_IMMUTABLE is dropped by default in Docker. Yes that mitigation would also work. -- Aleksa Sarai Senior Software Engineer (Containers) SUSE Linux GmbH <https://www.cyphar.com/> Download attachment "signature.asc" of type "application/pgp-signature" (834 bytes)
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