Bug#586480: openssh-server: chroot directive is not working when using FISH (File transfer of shell with midnight commander)
Package: openssh-server
Version: 1:5.1p1-5
Severity: critical
Tags: security
Justification: root security hole
Hello,
I have successfully configured my ssh server to chroot users, by followinf the directives described here:
http://www.debian-administration.org/articles/590 ie. OpenSSH SFTP chroot() with ChrootDirectory
The chroot option seems to work well when I use the sftp command, ie I cannot see any directory at all.
However, if I use the fish protocol [1] included in midnight commander, I can see the full filesystem hierarchy,
and even transfer files from the etc folder, etc...
I don't know if it's a configuration problem on my side, but if there is an option do disallow fish
when using chroot, that need to be explicitly specified. Otherwise, debian users may relay
on a chrooted server that can be bypassed by a simple manipulation...
[1] http://en.wikipedia.org/wiki/Files_transferred_over_shell_protocol
Kind regards,
André Rodier.
Here my ssh config: See the end for chroot config
-----8<------------------------------------------------------------
# Package generated configuration file
# See the sshd(8) manpage for details
# What ports, IPs and protocols we listen for
Port 22
# Use these options to restrict which interfaces/protocols sshd will bind to
#ListenAddress ::
#ListenAddress 0.0.0.0
Protocol 2
# HostKeys for protocol version 2
HostKey /etc/ssh/ssh_host_rsa_key
HostKey /etc/ssh/ssh_host_dsa_key
#Privilege Separation is turned on for security
UsePrivilegeSeparation yes
# Lifetime and size of ephemeral version 1 server key
KeyRegenerationInterval 3600
ServerKeyBits 768
# Logging
SyslogFacility AUTH
LogLevel DEBUG
# Authentication:
LoginGraceTime 120
PermitRootLogin no
StrictModes yes
RSAAuthentication yes
PubkeyAuthentication yes
#AuthorizedKeysFile %h/.ssh/authorized_keys
# Don't read the user's ~/.rhosts and ~/.shosts files
IgnoreRhosts yes
# For this to work you will also need host keys in /etc/ssh_known_hosts
RhostsRSAAuthentication no
# similar for protocol version 2
HostbasedAuthentication no
# Uncomment if you don't trust ~/.ssh/known_hosts for RhostsRSAAuthentication
#IgnoreUserKnownHosts yes
# To enable empty passwords, change to yes (NOT RECOMMENDED)
PermitEmptyPasswords no
# Change to yes to enable challenge-response passwords (beware issues with
# some PAM modules and threads)
ChallengeResponseAuthentication no
# Change to no to disable tunnelled clear text passwords
#PasswordAuthentication yes
# Kerberos options
#KerberosAuthentication no
#KerberosGetAFSToken no
#KerberosOrLocalPasswd yes
#KerberosTicketCleanup yes
# GSSAPI options
#GSSAPIAuthentication no
#GSSAPICleanupCredentials yes
X11Forwarding yes
X11DisplayOffset 10
PrintMotd no
PrintLastLog yes
TCPKeepAlive yes
#UseLogin no
#MaxStartups 10:30:60
#Banner /etc/issue.net
# Allow client to pass locale environment variables
AcceptEnv LANG LC_*
UsePAM no
UseDNS no
#ChrootDirectory
# Subsystem sftp /usr/lib/openssh/sftp-server
Subsystem sftp internal-sftp
Match group sftponly
ChrootDirectory /home/%u
X11Forwarding no
AllowTcpForwarding no
AllowAgentForwarding no
ForceCommand internal-sftp
-----8<------------------------------------------------------------
-- System Information:
Debian Release: 5.0.3
APT prefers stable
APT policy: (500, 'stable')
Architecture: amd64 (x86_64)
Kernel: Linux 2.6.26-2-amd64 (SMP w/1 CPU core)
Locale: LANG=en_GB.UTF-8, LC_CTYPE=en_GB.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/bash
Versions of packages openssh-server depends on:
ii adduser 3.110 add and remove users and groups
ii debconf [debcon 1.5.24 Debian configuration management sy
ii dpkg 1.14.29 Debian package management system
ii libc6 2.7-18lenny4 GNU C Library: Shared libraries
ii libcomerr2 1.41.3-1 common error description library
ii libkrb53 1.6.dfsg.4~beta1-5lenny4 MIT Kerberos runtime libraries
ii libpam-modules 1.0.1-5+lenny1 Pluggable Authentication Modules f
ii libpam-runtime 1.0.1-5+lenny1 Runtime support for the PAM librar
ii libpam0g 1.0.1-5+lenny1 Pluggable Authentication Modules l
ii libselinux1 2.0.65-5 SELinux shared libraries
ii libssl0.9.8 0.9.8g-15+lenny6 SSL shared libraries
ii libwrap0 7.6.q-16 Wietse Venema's TCP wrappers libra
ii lsb-base 3.2-20 Linux Standard Base 3.2 init scrip
ii openssh-blackli 0.4.1 list of default blacklisted OpenSS
ii openssh-client 1:5.1p1-5 secure shell client, an rlogin/rsh
ii procps 1:3.2.7-11 /proc file system utilities
ii zlib1g 1:1.2.3.3.dfsg-12 compression library - runtime
Versions of packages openssh-server recommends:
pn openssh-blacklist-extra <none> (no description available)
pn xauth <none> (no description available)
Versions of packages openssh-server suggests:
pn molly-guard <none> (no description available)
pn rssh <none> (no description available)
pn ssh-askpass <none> (no description available)
-- debconf information:
ssh/vulnerable_host_keys:
ssh/new_config: true
* ssh/use_old_init_script: true
ssh/encrypted_host_key_but_no_keygen:
ssh/disable_cr_auth: false
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