openssh unix dev - Jul 2003 - possible bug + patch : OpenSSH 3.6.1p2 +UnixWare 7.1.1 +SSH2 + P asswordAuthentication no + PermitEmptyPasswords yes

Greetings,

When PasswordAuthentication no + PermitEmptyPasswords yes
SSH2 allows access to a passwordless account without a valid key.

This is my patch:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
wormhole# diff -u auth2-none.c.old  auth2-none.c
--- auth2-none.c.old    Thu Jul 17 06:23:24 2003
+++ auth2-none.c        Thu Jul 17 06:44:42 2003
@@ -100,7 +100,9 @@
        if (check_nt_auth(1, authctxt->pw) == 0)
                return(0);
 #endif
-       return PRIVSEP(auth_password(authctxt, "")) &&
authctxt->valid;
+       return PRIVSEP(auth_password(authctxt, ""))
+               && authctxt->valid
+               && options.password_authentication;
 }

 Authmethod method_none = {
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The authentication method "none" (which allows the user to log 
into an account with an empty password) returns 1 only if 
PasswordAuthentication is set to "yes".

complete debug of problem below:

uw7: /usr/udd1/dev/original/openssh-3.6.1p2 # ./sshd -p 5000 -d -d -d
debug3: Seeding PRNG from /usr/local/libexec/ssh-rand-helper
debug2: read_server_config: filename /etc/ssh/sshd_config
debug1: sshd version OpenSSH_3.6.1p2
debug1: private host key: #0 type 0 RSA1
debug3: Not a RSA1 key file /etc/ssh/ssh_host_dsa_key.
debug1: read PEM private key done: type DSA
debug1: private host key: #1 type 2 DSA
debug1: Bind to port 5000 on ::.
debug1: Bind to port 5000 on 0.0.0.0.
Server listening on 0.0.0.0 port 5000.
Generating 768 bit RSA key.
RSA key generation complete.
debug1: Server will not fork when running in debugging mode.
Connection from 192.168.1.1 port 1199
debug1: Client protocol version 2.0; client software version OpenSSH_3.5p1
FreeBSD-20030201
debug1: match: OpenSSH_3.5p1 FreeBSD-20030201 pat OpenSSH*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-1.99-OpenSSH_3.6.1p2
debug1: list_hostkey_types: ssh-dss
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug2: kex_parse_kexinit:
diffie-hellman-group-exchange-sha1,diffie-hellman-group1-sha1
debug2: kex_parse_kexinit: ssh-dss
debug2: kex_parse_kexinit:
aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour,aes192-cbc,aes256-cbc,r
ijndael-cbc at lysator.liu.se
debug2: kex_parse_kexinit:
aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour,aes192-cbc,aes256-cbc,r
ijndael-cbc at lysator.liu.se
debug2: kex_parse_kexinit:
hmac-md5,hmac-sha1,hmac-ripemd160,hmac-ripemd160 at openssh.com,hmac-sha1-96,hm
ac-md5-96
debug2: kex_parse_kexinit:
hmac-md5,hmac-sha1,hmac-ripemd160,hmac-ripemd160 at openssh.com,hmac-sha1-96,hm
ac-md5-96
debug2: kex_parse_kexinit: none,zlib
debug2: kex_parse_kexinit: none,zlib
debug2: kex_parse_kexinit:
debug2: kex_parse_kexinit:
debug2: kex_parse_kexinit: first_kex_follows 0
debug2: kex_parse_kexinit: reserved 0
debug2: kex_parse_kexinit:
diffie-hellman-group-exchange-sha1,diffie-hellman-group1-sha1
debug2: kex_parse_kexinit: ssh-dss,ssh-rsa
debug2: kex_parse_kexinit:
aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour,aes192-cbc,aes256-cbc,r
ijndael-cbc at lysator.liu.se
debug2: kex_parse_kexinit:
aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour,aes192-cbc,aes256-cbc,r
ijndael-cbc at lysator.liu.se
debug2: kex_parse_kexinit:
hmac-md5,hmac-sha1,hmac-ripemd160,hmac-ripemd160 at openssh.com,hmac-sha1-96,hm
ac-md5-96
debug2: kex_parse_kexinit:
hmac-md5,hmac-sha1,hmac-ripemd160,hmac-ripemd160 at openssh.com,hmac-sha1-96,hm
ac-md5-96
debug2: kex_parse_kexinit: none,zlib
debug2: kex_parse_kexinit: none,zlib
debug2: kex_parse_kexinit:
debug2: kex_parse_kexinit:
debug2: kex_parse_kexinit: first_kex_follows 0
debug2: kex_parse_kexinit: reserved 0
debug2: mac_init: found hmac-md5
debug1: kex: client->server aes128-cbc hmac-md5 none
debug2: mac_init: found hmac-md5
debug1: kex: server->client aes128-cbc hmac-md5 none
debug1: SSH2_MSG_KEX_DH_GEX_REQUEST received
debug1: SSH2_MSG_KEX_DH_GEX_GROUP sent
debug2: dh_gen_key: priv key bits set: 129/256
debug2: bits set: 1619/3191
debug1: expecting SSH2_MSG_KEX_DH_GEX_INIT
debug2: bits set: 1601/3191
debug1: SSH2_MSG_KEX_DH_GEX_REPLY sent
debug2: kex_derive_keys
debug2: set_newkeys: mode 1
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug2: set_newkeys: mode 0
debug1: SSH2_MSG_NEWKEYS received
debug1: KEX done
debug1: userauth-request for user natis service ssh-connection method none
debug1: attempt 0 failures 0
debug3: allowed_user: today 12244 sp_expire -1 sp_lstchg 12240 sp_max -1
debug2: input_userauth_request: setting up authctxt for natis
debug2: input_userauth_request: try method none
Accepted none for natis from 192.168.1.1 port 1199 ssh2
debug1: Entering interactive session for SSH2.
debug1: fd 7 setting O_NONBLOCK
debug1: fd 8 setting O_NONBLOCK
debug1: server_init_dispatch_20
debug1: server_input_channel_open: ctype session rchan 0 win 65536 max 16384
debug1: input_session_request
debug1: channel 0: new [server-session]
debug1: session_new: init
debug1: session_new: session 0
debug1: session_open: channel 0
debug1: session_open: session 0: link with channel 0
debug1: server_input_channel_open: confirm session
debug1: server_input_channel_req: channel 0 request pty-req reply 0
debug1: session_by_channel: session 0 channel 0
debug1: session_input_channel_req: session 0 req pty-req
debug1: Allocating pty.
debug1: session_pty_req: session 0 alloc /dev/pts/2
debug3: tty_parse_modes: SSH2 n_bytes 251
debug3: tty_parse_modes: ospeed 9600
debug3: tty_parse_modes: ispeed 9600
debug3: tty_parse_modes: 1 3
debug3: tty_parse_modes: 2 28
debug3: tty_parse_modes: 3 127
debug3: tty_parse_modes: 4 21
debug3: tty_parse_modes: 5 4
debug3: tty_parse_modes: 6 255
debug3: tty_parse_modes: 7 255
debug3: tty_parse_modes: 8 17
debug3: tty_parse_modes: 9 19
debug3: tty_parse_modes: 10 26
debug3: tty_parse_modes: 11 25
debug3: tty_parse_modes: 12 18
debug3: tty_parse_modes: 13 23
debug3: tty_parse_modes: 14 22
debug1: Ignoring unsupported tty mode opcode 17 (0x11)
debug3: tty_parse_modes: 18 15
debug3: tty_parse_modes: 30 0
debug3: tty_parse_modes: 31 0
debug3: tty_parse_modes: 32 0
debug3: tty_parse_modes: 33 0
debug3: tty_parse_modes: 34 0
debug3: tty_parse_modes: 35 0
debug3: tty_parse_modes: 36 1
debug3: tty_parse_modes: 38 1
debug3: tty_parse_modes: 39 1
debug3: tty_parse_modes: 40 0
debug3: tty_parse_modes: 41 1
debug3: tty_parse_modes: 50 1
debug3: tty_parse_modes: 51 1
debug3: tty_parse_modes: 53 1
debug3: tty_parse_modes: 54 1
debug3: tty_parse_modes: 55 0
debug3: tty_parse_modes: 56 0
debug3: tty_parse_modes: 57 0
debug3: tty_parse_modes: 58 0
debug3: tty_parse_modes: 59 1
debug3: tty_parse_modes: 60 1
debug3: tty_parse_modes: 61 1
debug3: tty_parse_modes: 62 1
debug3: tty_parse_modes: 70 1
debug3: tty_parse_modes: 72 1
debug3: tty_parse_modes: 73 0
debug3: tty_parse_modes: 74 0
debug3: tty_parse_modes: 75 0
debug3: tty_parse_modes: 90 1
debug3: tty_parse_modes: 91 1
debug3: tty_parse_modes: 92 0
debug3: tty_parse_modes: 93 0
debug1: server_input_channel_req: channel 0 request shell reply 0
debug1: session_by_channel: session 0 channel 0
debug1: session_input_channel_req: session 0 req shell
debug1: fd 10 setting O_NONBLOCK
debug2: fd 9 is O_NONBLOCK

Thanks
Vikash

On Thu, 17 Jul 2003, Vikash Badal - PCS wrote:

[..]
> -       return PRIVSEP(auth_password(authctxt, "")) &&
authctxt->valid;
> +       return PRIVSEP(auth_password(authctxt, ""))
> +               && authctxt->valid
> +               && options.password_authentication;
>  }
>
If this fixes your problem then the bug is in auth_password() function
call.  This will never go into the tree because this is just a bandaid.

I could have already swore I pointed this out a few days ago.

- Ben