Date: Wed, 18 Oct 2017 12:55:21 +0000 From: Robert Watson <robertcwatson1@...il.com> To: oss-security@...ts.openwall.com, Bastian Blank <waldi@...ian.org> Subject: Re: CVE-2017-8805: Unsafe symlinks not filtered in Debian mirror script ftpsync Since security is determined by file and directory permissions and ownership, not by symlinks, wouldn't the fact that a malicious user did not have permissions to access the symlink's target file/directory prevent any harm? On Tue, Oct 17, 2017, 12:27 Bastian Blank <waldi@...ian.org> wrote: > Hi folks > > ftpsync is the tool we use to mirror Debian everywhere. It uses rsync > to do the heavy lifting. > > rsync can copy symlinks. We enable this option, as the Debian tree > includes symlinks in various of locations. Unless a special option > (--safe-links) is given, such symlinks can point to arbitrary locations, > even outside of the mirror tree. > > An attacker with the ability to add symlinks to the upstream mirror can > create symlinks to arbitrary files or even directories. Depending on > the config, a HTTP server will follow such symlinks. > > Upstream patch: > --------------- > -> > https://anonscm.debian.org/cgit/mirror/archvsync.git/commit/?id=d1ca2ab2210990b6dfb664cd6776a41b71c48016 > > Regards, > Bastian > > -- > Beam me up, Scotty! > -- Robert "DocSalvager" Watson ... trust in truth keeps hope alive www.DocSalvage.info
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