oss-sec mailing list archives
Re: Are `su user' and/or `sudo -u user sh' considered dangerous?
From: Jakub Wilk <jwilk () jwilk net>
Date: Tue, 12 Jun 2018 13:38:36 +0200
* Georgi Guninski <guninski () guninski com>, 2018-06-12, 13:17:
https://j.ludost.net/blog/archives/2018/06/12/are_su_user_andor_sudo_-u_user_sh_considered_dangerous/index.htmlPer vague memory I discussed half of this with some linux crowd and they said "won't fix" long ago.`su user' and `sudo -u user sh' give the user the fd of root's tty and it is readable and writable. After closing the session, the user can keep it and on root's tty potentially do:1. inject keypresses via ioctl() and/or2. read the output of root's tty, probably with some analogue of tee(1).Is this really a concern?
This class of vulnerabilities has been known since at least 2005: https://bugzilla.redhat.com/show_bug.cgi?id=173008 (CVE-2005-4890) It was last discussed on oss-security in 2017: http://seclists.org/oss-sec/2017/q2/412
Any workarounds?
For sudo, there's the "use_pty" flag. (It's not enabled by default.) -- Jakub Wilk
Current thread:
- Are `su user' and/or `sudo -u user sh' considered dangerous? Georgi Guninski (Jun 12)
- Re: Are `su user' and/or `sudo -u user sh' considered dangerous? Jakub Wilk (Jun 12)
- Re: Are `su user' and/or `sudo -u user sh' considered dangerous? Jordan Glover (Jun 12)
- Re: Are `su user' and/or `sudo -u user sh' considered dangerous? Todd C. Miller (Jun 12)
- Re: Are `su user' and/or `sudo -u user sh' considered dangerous? Georgi Guninski (Jun 13)
- Re: Are `su user' and/or `sudo -u user sh' considered dangerous? Georgi Guninski (Jun 13)
- Re: Are `su user' and/or `sudo -u user sh' considered dangerous? Jakub Wilk (Jun 14)
- Re: Are `su user' and/or `sudo -u user sh' considered dangerous? Georgi Guninski (Jun 15)
- Re: Are `su user' and/or `sudo -u user sh' considered dangerous? Jordan Glover (Jun 12)
- Re: Are `su user' and/or `sudo -u user sh' considered dangerous? Jakub Wilk (Jun 12)