Re: Ok.. who is backdooring /usr/bin/login on SunOS?

[casper () Holland Sun COM (Casper Dik)]

> 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