bin/58893: OPIE implementation bug

[Sergey Sysoev]

>Number:         58893
>Category:       bin
>Synopsis:       OPIE implementation bug
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Mon Nov 03 11:00:30 PST 2003
>Closed-Date:
>Last-Modified:
>Originator:     Sergey Sysoev
>Release:        FreeBSD 4.9-RELEASE i386
>Organization:
>Environment:
System: FreeBSD srv.faeton1.ru 4.9-RELEASE FreeBSD 4.9-RELEASE #0: Thu Oct 30 19:18:45 OMST 2003 ssa at srv.faeton1.ru:/usr/src/sys/compile/SRV i386

>Description:
	1. opiepasswd produce incorrect seed output during password change
	2. opiekey produce incorrect response in case of 0 (zero) sequence number
	3. pam_opie.so can allow login attempts in case with negative sequence number

>How-To-Repeat:

*** 1 *** opiepasswd/opiekey

I've added user using `opiepasswd -c "ssa"`

   mx2# opiepasswd -c "ssa"
   Adding ssa:
   Only use this method from the console; NEVER from remote. If you are using
   telnet, xterm, or a dial-in, type ^C now or exit with no password.
   Then run opiepasswd without the -c parameter.
   Using MD5 to compute responses.
   Enter new secret pass phrase:
   Again new secret pass phrase:

  ID ssa OTP key is 499 mx1759
  WADE IFFY LAWN MEAD DANG BUB
  mx2#

And now I want to change it

   mx2# opiepasswd "ssa"
   Updating ssa:
   You need the response from an OTP generator.
   New secret pass phrase:
          otp-md5 499 mx17
          Response:

You see that seed equal 'mx17', using opiekey:

   mx2# opiekey 499 mx17
   Using the MD5 algorithm to compute response.
   Seeds must be greater than 5 characters long.
   mx2#

So it is not possible to update password in /etc/opiekey file, you
have to edit it manually and that add password again via 'opiepasswd'.




*** 2***  opiekey

opiekey could not generate response for zero sequence number when it
specified directly:

   mx2# opiekey -a 0 vo6199
   Using the MD5 algorithm to compute response.
   Sequence number 0 is not positive.

but it works fine in case of:

   mx2# opiekey -n5 1 vo6199
   Using the MD5 algorithm to compute response.
   Reminder: Don't use opiekey from telnet or dial-in sessions.
   Enter secret pass phrase:
   0: OAK SEW CULT FALL AX WAND
   1: BOUT AID SOOT BUT SIT BILK
   mx2#





*** 3 *** pam_opie.so

After successful login with 0 (zero) sequence number, trying to do it again
(sequence number has been decreased, right?)

   mx2# ssh ssa at 192.168.90.250
   otp-md5 -1 (null) ext
   Password:

Is  it  impossible  to calculate response to '-1' so trying to use any
password  to  skip  pam_opie  and login with next pam module. But here
login   hangs   and  there  is  _no_way_  to  login  remotely  because
pam_opie.so is the top line of pam.conf

After about 1-2 minutes timeout with "Connection closed by 192.168.90.250"



>Fix:
	
	correct opiepasswd/opiekey checking rules and output
	pam_opie.so, to check seq.number before processing login, at seq.number eq zero 
	reinit it simultaneously with different seed reinitialization for the same passphrase?




>Release-Note:
>Audit-Trail:
>Unformatted: