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Date: Thu, 26 Jan 2017 18:35:12 +0100
From: Noryungi <noryungi@...il.com>
To: oss-security@...ts.openwall.com
Subject: Re: Re: OpenSSH: CVE-2015-6565 (pty issue in 6.8-6.9)
 can lead to local privesc on Linux

Does not work on centos 7.1 (unpatched) running stock openssh.

TTY capture works, /tmp/sh is created but user is unprivileged.

On Jan 26, 2017 5:52 PM, <up201407890@...nos.dcc.fc.up.pt> wrote:

> Hi list,
>
> I know I'm late to the party, but I was bored, so I decided to write an
> exploit for CVE-2015-6565 which affects OpenSSH 6.8-6.9
> It is mostly considered to be a "DoS", even though Jann Horn publicly told
> how it could be exploited for local privilege escalation, but I guess its
> either PoC||GTFO for users to update.
>
> From https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-6565
>
> "sshd in OpenSSH 6.8 and 6.9 uses world-writable permissions for TTY
> devices, which allows local users to cause a denial of service (terminal
> disruption) or possibly have unspecified other impact by writing to a
> device, as demonstrated by writing an escape sequence."
>
> I think the description should be updated.
>
> $ gcc not_an_sshnuke.c -o not_an_sshnuke
> $ ./not_an_sshnuke /dev/pts/3
> [*] Waiting for slave device /dev/pts/3
> [+] Got PTY slave /dev/pts/3
> [+] Making PTY slave the controlling terminal
> [+] SUID shell at /tmp/sh
> $ /tmp/sh --norc --noprofile -p
> # id
> euid=0(root) groups=0(root)
>
> Thanks,
> Federico Bento.
>
>
>
> ----------------------------------------------------------------
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>

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