Subject:
Glibc Local Root Exploit
Date:
Wed, 10 Jan 2001 00:06:48 -0700
From:
Charles Stevenson <[EMAIL PROTECTED]>
To:
[EMAIL PROTECTED]
Hi all,
This has been bouncing around on vuln-dev and the debian-devel lists.
It
effects glibc >= 2.1.9x and it would seem many if not all OSes using
these
versions of glibc. Ben Collins writes, "This wasn't supposed to happen,
and
the actual fix was a missing comma in the list of secure env vars that
were
supposed to be cleared when a program starts up suid/sgid (including
RESOLV_HOST_CONF)." The exploit varies from system to system but in our
devel version of Yellow Dog Linux I was able to print the /etc/shadow
file
as a normal user in the following manner:
export RESOLV_HOST_CONF=/etc/shadow
ssh whatever.host.com
Other programs have the same effect depending on the defaults for the
system. I have tested this on Red Hat 7.0, Yellow Dog Linux 2.0
(prerelease), and Debian Woody. Others have reported similar results on
slackware and even "home brew[ed]" GNU/Linux.
Best Regards,
Charles Stevenson
Software Engineer
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