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Re: Ok.. who is backdooring /usr/bin/login on SunOS?
From: casper () Holland Sun COM (Casper Dik)
Date: Wed, 10 May 1995 16:29:29 +0200


I have now come upon the 5th example of a 1s compliment passwords being 
put into /usr/bin/login on different systems... Each one has a different 
password, and not all act the same, some allowing you to get in with

       any_userid+given_passwd==root_shell
               and the other 
      real_userid+given_passwd==real_user_shell [including root]

One of the systems also has the 1s compliment string '/tmp/.tty'.. I have 
yet to see that file used.. is anyone familiar with these attacks?  I've 
looked [briefly, I admit] through the archives of bugtraq and can't find 
any notes on this one...

The attack looks familiar, though I've only seen it with one
of the passwords as 1-complement, the other as plain text.

I've only seen it as change to a dynamically linked libc on SunOS 4
machines (replacing crypt w/ its own routines).

All of the systems so-compromised have been [at some point] running NCSA 
HTTP servers.  That is the only similar attack route that I have been 
able to pin down.  Is there a toolkit out there that hacks login via the 
http holes?

Usually such elaborate hacks do not exist, it's more of a modular
three step approach:

        - get on a machine (perhaps thru HTTP, but very common
          is password snooping)
        - get root (any of the hoels you mention will do)
        - modify libc.so/login.


Casper



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