Bugtraq mailing list archives
rh 6.2 - gid compromises, etc
From: lcamtuf () TPI PL (Michal Zalewski)
Date: Wed, 21 Jun 2000 12:54:08 +0200
Probably it's nothing exciting, but several packets supplied with RH 6.2 will allow <500 gid/uid compromises. On every system it HAS some kind of meaning - sometimes just a little (exceeding quotas, hiding from accounting, anonymous intrusions to other systems) - but sometimes compromised uucp or news privledges might be used to intercept/modify/deny important traffic on server itself. IMHO, it's good to minimalise number of setuid root applications in system. But moving to setgids won't solve anything. Of course, you might avoid root security compromise, but uid/gid 'news' gained on newsserver, 'http' or 'nobody' gained on webserver or 'uucp' gained on UUCP machine is not the thing that should happen. I checked about 15 setgid applications from RH 6.2, performing some basic tests - environment parsing, privledges dropping and input validation. And it looks bad: - slrnpull (setgid: news) - using eg. NNTPSERVER environmental variable, you can cause nice SEGV... egid==news, of course. On systems running innd server (and probably other newsservers as well), group 'news' can be used to control content of whole spool, and to elevate privledges, gaining euid news. From this point, we can simply takeover nntp service. Under some conditions, inews can be used in the same way, but bug is hidden a little bit deeper. I'll leave it as an exercise to readers (and maintainers - please audit your code, not only fix published bugs), - gkermit - can read/write/append files with egid==uucp; these file include many /dev/ entries, /etc/uucp/passwd etc; can be dangerous on systems running uucp. - slocate - custom input file can be specified using LOCATE_PATH; due to almost no input validation, it's possible to supply many different input patterns, some of them will cause potentially exploitable SEGVs; please review this code. Ah, forgotten, gid slocate can be used to access slocate database in unrestricted mode (every file in filesystem indexed, including eg. /root, web scripts etc), Also, I'm still surprised with number of world-writable files/directories shipped with every RH installation. It is difficult to perform something like: # find / -perm -2 \! -type l -exec ls -ld {} \; ? People are very often setting up /tmp on separate partitions, with eg. nosuid option, the same about /home, but most of them are missing _a_lot_ of these directories (some of them are even setuid, huh). _______________________________________________________ Michal Zalewski [lcamtuf () tpi pl] [tp.internet/security] [http://lcamtuf.na.export.pl] <=--=> bash$ :(){ :|:&};: =-----=> God is real, unless declared integer. <=-----=
Current thread:
- Re: NAI WebShield SMTP does not scan base64 encoding Fronck, Destry (Jun 20)
- Re: NAI WebShield SMTP does not scan base64 encoding chris.paget () ANALYSYS COM (Jun 20)
- BlackICE by Network ICE Corp vulnerability against Back Orifice 1.2 Juancho Forlanda (Jun 20)
- BEA WebLogic /file/ showcode vulnerability stuart.mcclure () FOUNDSTONE COM (Jun 20)
- Re: BlackICE by Network ICE Corp vulnerability against Back Orifice 1.2 Mike DeMaria (Jun 21)
- <Possible follow-ups>
- Re: NAI WebShield SMTP does not scan base64 encoding Sato, Ken (Jun 20)
- Microsoft Security Bulletin MS00-038 Update Microsoft Product Security (Jun 20)
- rh 6.2 - gid compromises, etc Michal Zalewski (Jun 21)
- Immunix OS 6.2 (StackGuarded Red Hat 6.2) Crispin Cowan (Jun 21)
- Warning regarding new kernel RPMs Joseph V Moss (Jun 21)
- Re: Warning regarding new kernel RPMs Dave Walter (Jun 22)
- Re: rh 6.2 - gid compromises, etc [+ MORE!!!] Stan Bubrouski (Jun 21)
- Re: rh 6.2 - gid compromises, etc [+ MORE!!!] Wietse Venema (Jun 23)
- Re: rh 6.2 - gid compromises, etc Stan Bubrouski (Jun 22)
- Allaire Security Bulletin (ASB00-15)- Workaround available for vu lnerabilities exposed by JRun 2.3.x code sample Jesse Noller (Jun 22)
- [RHSA-2000:038-01] Zope update bugzilla () REDHAT COM (Jun 22)
- FreeBSD Security Advisory: FreeBSD-SA-00:23.ip-options FreeBSD Security Advisories (Jun 22)
- Re: FreeBSD Security Advisory: FreeBSD-SA-00:23.ip-options yeti (Jan 13)