[Bug 1499392] Re: OpenSSH Security and SHA1

[Seth Arnold]

Hello Eldin, you're right that it is time to begin migrating away from
SHA-1 in default OpenSSH configurations. However there is some
historical baggage in parts of the launchpad infrastructure that
prevented upgrading algorithms earlier. (Strictly speaking, the defaults
aren't tied to launchpad but a configuration that doesn't allow
developers to work out of the box is less than ideal.)

Some related bugs that might help explain the situation:
https://bugs.launchpad.net/ubuntu/+source/openssh/+bug/1445620
https://bugs.launchpad.net/ubuntu/+source/openssh/+bug/1445624
https://bugs.launchpad.net/ubuntu/+source/openssh/+bug/1445625

A site with many general guidelines that may influence more than just
default keysize and hash selections:
https://stribika.github.io/2015/01/04/secure-secure-shell.html

And, of course, whatever we select should be tested against Cisco gear,
since there's always a bug or two with every openssh configuration
change that prevents people from logging into or using Cisco equipment.

Colin, is it feasible to start making algorithm changes yet?

Thanks

** Changed in: openssh (Ubuntu)
       Status: New => Confirmed

-- 
You received this bug notification because you are a member of Ubuntu
Foundations Bugs, which is subscribed to openssh in Ubuntu.
https://bugs.launchpad.net/bugs/1499392

Title:
  OpenSSH Security and SHA1

Status in openssh package in Ubuntu:
  Confirmed

Bug description:
  We should enhance Security by disabling SHA1 or, if not possible
  (older Clients) by changing the KexAlgorithms, Ciphers and MACs order.

  For e.g. by :

  1. If we add Support for older Clients we should change this:

  #### OpenSSH Security ####

  KexAlgorithms curve25519-sha256 at libssh.org,diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1
  Ciphers chacha20-poly1305 at openssh.com,aes256-gcm at openssh.com,aes128-gcm at openssh.com,aes256-ctr,aes192-ctr,aes128-ctr
  MACs hmac-sha2-512-etm at openssh.com,hmac-sha2-256-etm at openssh.com,hmac-ripemd160-etm at openssh.com,umac-128-etm at openssh.com,hmac-sha2-512,hmac-sha2-256,hmac-ripemd160,umac-128 at openssh.com

  2.  If we just Support new Clients we should change this :

  [...]
  HostKey /etc/ssh/ssh_host_rsa_key
  HostKey /etc/ssh/ssh_host_ed25519_key
  [...]

  #### OpenSSH Security ####

  KexAlgorithms curve25519-sha256 at libssh.org,diffie-hellman-group-exchange-sha256
  Ciphers chacha20-poly1305 at openssh.com,aes256-gcm at openssh.com,aes128-gcm at openssh.com,aes256-ctr,aes192-ctr,aes128-ctr
  MACs hmac-sha2-512-etm at openssh.com,hmac-sha2-256-etm at openssh.com,hmac-ripemd160-etm at openssh.com,umac-128-etm at openssh.com,hmac-sha2-512,hmac-sha2-256,hmac-ripemd160,umac-128 at openssh.com

  For more Information about my report go here:

  https://github.com/scaleway/image-ubuntu/pull/35

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/openssh/+bug/1499392/+subscriptions