OSEC

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Bugtraq archives for 3rd quarter (Jul-Aug) 1995: Re: Linux NIS security problem hole and fix

Re: Linux NIS security problem hole and fix

Tim Chown (T.J.Chownecs.soton.ac.uk)
Fri, 8 Sep 1995 09:51:47 +0100 

On Thu, 7 Sep 1995, Ken Weaverling wrote:

> I was told by someone that this hole is "well known" and has been discussed
> on the LINUX security list for a while now. A few people have emailed me
> telling me what it was too, so it is obvious that this is "known" about.

Here are my observations on Slackware 2.3/ kernel 1.2.13.

I can say that logging in as + on SW2.3/1.2.13 doesn't give
you anything bar a login refused, IF the passwd entry says
just '+'.   The latest SW says that just + is all you need to
pull in entries with the latest libc in use that comes with it.

However, if the entry says '+::0:0:::' then you can login as
root via telnet (well, you could if we didn't bar direct
root logins), but just 'su +' will get you root of course.

Using an entry of '+:*:0:0:::' allows people to login but
disallows the root hole.

Lovely :)

Cheers,
Tim