Date: Sun, 11 Nov 2012 00:18:13 -0700 From: Kurt Seifried <kseifried@...hat.com> To: oss-security@...ts.openwall.com CC: Yves-Alexis Perez <corsac@...ian.org>, 692791@...s.debian.org, team@...urity.debian.org, cups-security@...le.com Subject: Re: Privilege escalation (lpadmin -> root) in cups -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 11/10/2012 05:49 AM, Yves-Alexis Perez wrote: > Hi, > > a Debian user reported a bug in our BTS concerning cupsd. The bug > is available at > http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=692791 and > upstream bug at http://www.cups.org/str.php?L4223 (restricted > because it's tagged security). > > I'm unsure right now if it's an upstream issue or specific to > Debian. On Red Hat Enterprise 6 and Fedora 16 the file is owned by root:sys, and the cupsd.conf defaults to: <Location /admin/conf> AuthType Default Require user @SYSTEM Order allow,deny </Location> so that should be like "root", "bin" and "adm" so yeah it would appear to be vendor specific. > Basically, members of the lpadmin group (which is the group having > admin rights to cups, meaning they're supposed to be able to > add/remove printeers etc.) have admin access to the web interface, > where they can edit the config file and set some “dangerous” > directives (like the log filenames), which enable them to read or > write files as the user running the cupsd webserver. > > In Debian case at least, it's run as root, meaning we have a > privilege escalation issue from lpadmin group to root. I think as a rule cupsd runs as root, to touch the various files/dirs/etc. > A fix would be to not run cupsd web server as root, and maybe to > restrict it to some kind of chroot so it doesn't have access to > sensitive files Tricky, /dev/*, log dirs, etc. Probably better to just use a print specific user/group and make all the standard locations owned by it, and require the admin to setup anything like say /non-standard/log/printers/ and so on. > Can a CVE be allocated for this? Please use CVE-2012-5519 for this issue. Also if other vendors could check the permissions/configs/etc. and reply if they are vulnerable that would be good. > Regards, > - -- Kurt Seifried Red Hat Security Response Team (SRT) PGP: 0x5E267993 A90B F995 7350 148F 66BF 7554 160D 4553 5E26 7993 -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iQIcBAEBAgAGBQJQn1E1AAoJEBYNRVNeJnmTAk0QAJzI9+STxsFAL7YJm4obCLAY PhVVZYau19qUxMlMEIahfvcV46/36zYZPKYtNJCNtH7G30lPqC2gfZ3upNbri8+u 71tZw15UMU6qAt/WNpfe9URjSNHRcO8tJ6OqN6u6er13YhdVkls6/Yudty1hAZoU wqd1xcBDv2uhaOsI5SswfSHC61JkBLRD7f13T6eWfSz5VT1TBwzJyP5yLTygx4jt wRnF/dBUSToSSqlLyP1gdSJWs6ksTtaVc7vHkCD2NVCZMPOn9lm9RiVj52Q1e/eR osbqbCwx8P3FC4w+MvN29+GbfRxdFA6ik4IHrpzR3Q+j105aQwIm0pubsENA2Lr3 YHnvoD4oysfr3zUGYs5dbH1qITTw2t5c2oAP1wfG7C52jjblg3AaDDSgACyJFciQ kqcmSnDdBdcpc9dpGFo02LSOkh1jyVmBUCjTfXiNkpTtMv++CtgGdQM6j/UgAh1Q 28yf5WhxuhdGPo28XNWbYj9ELAe4aDAssggTL+ysM8Xjc23hfBXowCNbkO4LqrlQ S14M04wi4eHrd8sj+DpzODm9ttOrnCCmzuNc5UBlxH2Mxk6LUVczU5RwDJ/wFPKA DoHFiCldax69zjRsLv/wgu3oNfn8Hi3Piyn/TfGmFEnnnejCUe5lDUIRzZgj+LoB 62nQOCDF/bsxQWwJdDPl =zMgY -----END PGP SIGNATURE-----
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