* Gentoo glibc security advisory
@ 2004-08-18 8:41 Thorsten Kukuk
2004-08-18 9:21 ` Jakub Jelinek
0 siblings, 1 reply; 2+ messages in thread
From: Thorsten Kukuk @ 2004-08-18 8:41 UTC (permalink / raw)
To: libc-hacker
Hi,
Gentoo has issued an advisory:
http://www.gentoo.org/security/en/glsa/glsa-200408-16.xml
"An attacker can gain the list of symbols a SUID application uses and their
locations and can then use a trojaned library taking precendence over those
symbols to gain information or perform further exploitation."
with the following patch:
http://www.gentoo.org/cgi-bin/viewcvs.cgi/sys-libs/glibc/files/glibc-sec-hotfix-20040804.patch?rev=1.1&content-type=text/vnd.viewcvs-markup
Does somebody knows more about this?
Thorsten
--
Thorsten Kukuk http://www.suse.de/~kukuk/ kukuk@suse.de
SuSE Linux AG Maxfeldstr. 5 D-90409 Nuernberg
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^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: Gentoo glibc security advisory
2004-08-18 8:41 Gentoo glibc security advisory Thorsten Kukuk
@ 2004-08-18 9:21 ` Jakub Jelinek
0 siblings, 0 replies; 2+ messages in thread
From: Jakub Jelinek @ 2004-08-18 9:21 UTC (permalink / raw)
To: Thorsten Kukuk; +Cc: libc-hacker
On Wed, Aug 18, 2004 at 10:41:35AM +0200, Thorsten Kukuk wrote:
>
> Hi,
>
> Gentoo has issued an advisory:
> http://www.gentoo.org/security/en/glsa/glsa-200408-16.xml
>
> "An attacker can gain the list of symbols a SUID application uses and their
That's true.
> locations
LD_DEBUG=all doesn't give you exact addresses of symbols
(but LD_TRACE_PRELINKING=1 does, maybe we should turn that off for
__libc_enable_secure and missing /etc/suid-debug).
It only tells you which libraries' symbols are used.
> and can then use a trojaned library taking precendence over those
> symbols to gain information
This is wrong. You can't LD_PRELOAD a trojaned library to a suid binary
(unless it is in the standard paths and sgid I think) nor you can
use LD_LIBRARY_PATH to trick it in any way.
> or perform further exploitation."
>
> with the following patch:
>
> http://www.gentoo.org/cgi-bin/viewcvs.cgi/sys-libs/glibc/files/glibc-sec-hotfix-20040804.patch?rev=1.1&content-type=text/vnd.viewcvs-markup
BTW,
* Fixes a glibc bug where certain envvars are interpreted
even if UNSECURE_ENVVARS says to drop them
is wrong, they are interpreted on purpose, but with caution if
__libc_enable_secure.
Jakub
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