oss-sec mailing list archives
openssh on linux rce in sftp-only mode
From: Hanno Böck <hanno () hboeck de>
Date: Wed, 8 Oct 2014 11:07:59 +0200
This seems CVE-worthy: http://seclists.org/fulldisclosure/2014/Oct/35 Quote: "OpenSSH lets you grant SFTP access to users without allowing full command execution using "ForceCommand internal-sftp". However, if you misconfigure the server and don't use ChrootDirectory, the user will be able to access all parts of the filesystem that he has access to - including procfs. On modern Linux kernels (>=2.6.39, I think), /proc/self/maps reveals the memory layout and /proc/self/mem lets you write to arbitrary memory positions. Combine those and you get easy RCE." It involves a number of issues coming together, however in the end it is an RCE with a legit configuration. Changelog: http://www.openssh.com/txt/release-6.7 * sftp-server(8): On platforms that support it, use prctl() to prevent sftp-server from accessing /proc/self/{mem,maps} -- Hanno Böck http://hboeck.de/ mail/jabber: hanno () hboeck de GPG: BBB51E42
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Current thread:
- openssh on linux rce in sftp-only mode Hanno Böck (Oct 08)
- Re: openssh on linux rce in sftp-only mode Jann Horn (Oct 08)
- Re: openssh on linux rce in sftp-only mode Josh Bressers (Oct 08)
- Re: openssh on linux rce in sftp-only mode Jann Horn (Oct 08)
- Re: openssh on linux rce in sftp-only mode Josh Bressers (Oct 08)
- Re: openssh on linux rce in sftp-only mode Jann Horn (Oct 08)
- Re: openssh on linux rce in sftp-only mode Yves-Alexis Perez (Oct 09)
- Re: openssh on linux rce in sftp-only mode Josh Bressers (Oct 08)
- Re: openssh on linux rce in sftp-only mode Vitor Ventura (Oct 09)
- Re: openssh on linux rce in sftp-only mode Jann Horn (Oct 08)