Re: vulnerability in su/PAM in redhat

From: Tani Hosokawa (unknownat_private)
Date: Fri Jun 11 1999 - 11:43:59 PDT

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    Well, I just checked it out on a fairly vanilla RH6.0 box, and it
    exhibited the same behaviour.  This is only a bug with PAM-enabled
    machines, Slackware, etc. do not have this problem.  Also, it exhibits
    this behaviour with or without shadowed passwords (I pwunconv'd and tried
    it just now, same thing happened).  I think it's a problem with one of the
    PAM modules.
    
    On Fri, 11 Jun 1999, C.J. Oster wrote:
    
    > Not if you have the latest shadow package installed.  If you type in an
    > incorrect password, you get an immediate 'Sorry.'  This may be correct for
    > earlier versions of the shadow suite, but I don't remember and I only have
    > the newest one installed.  Latest version is at
    > ftp://ftp.ists.pwr.wroc.pl/pub/linux/shadow/
    > >I was talking to some guy on IRC (st2) and he asked me to mention to
    > >bugtraq (because he's not on the list) that the PAMified su that comes
    > >with redhat has a slight hole. When you try to su to root (for example) if
    > >it's successful, immediately gives you a shell prompt.  Otherwise, it
    > >delays a full second, then logs an authentication failure to syslog.  If
    > >you hit break in that second, no error, plus you know that the password
    > >was bad, so you can brute force root's password.  I wrote a little
    > >threaded Perl prog that tested it (with a 0.25 second delay before the
    > >break) to attack my own password (with my password in the wordlist) and it
    > >seemed to work just fine, even with my own password hundreds of words down
    > >in the list, so it seems pretty predictable, as long as the server's under
    > >very little load (else you get a delay no matter what, and it screws the
    > >whole process by giving false negatives).
    
    ---
    tani hosokawa
    river styx internet
    



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