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RE: Disable service identification

Subject: RE: Disable service identification
Date: Fri, 13 Jul 2007 16:47:08 +0100
Michel is still right.

 

Inetd is trying to start the non-existent executable, when a connection is
made, and can't, so terminates the connection immediately.

 

Further connections from Nessus, with a short, or nearly no delay, do the
same, and inetd will detect this *perfectly correctly*, as a misconfigured
inetd.conf.  As it's misconfigured it then backs off and doesn't allow any
further connections for a while.  This is the documented behaviour of
Solaris 8:

 

           -r  count interval

 

           count  and interval are decimal numbers that represent

           the  maximum   count  of  invocations  per interval of

           seconds a service may be started before the service is

           considered  ``broken.''

 

           Once considered ``broken,'' a server is suspended  for

           ten  minutes.   After ten minutes, inetd again enables

           service, hoping the server behaves correctly.

 

           If the -r flag is  not  specified,  inetd  behaves  as

           though -r40 60 was specified.

 

So you would expect, by default 40 connections in under 60 seconds of your
misconfigured Xaudio service to result in a 10 minute suspension of the
Xaudio service.

 

Anything beyond this behaviour (e.g. disabling telnet in any way) is a
Solaris 8 bug, and certainly nothing to do with Nessus.

 

Dom

Dom De Vitto  | Security Consultant

Virgin Media,  Crawley Court, Crawley, Winchester, Hants, SO21 2QA

M: 07855 805 271   D: 01483 87 5500   E: Dom.DeVitto@VirginMedia.co.uk

-----Original Message-----
From: nessus-bounces@list.nessus.org [mailto:nessus-bounces@list.nessus.org]
On Behalf Of Pete Duffin
Sent: 12 July 2007 22:34
To: Michel Arboi
Cc: nessus@list.nessus.org
Subject: Re: Disable service identification

 

I'll have a look in the morning regarding the messages you mentioned.

 

However, I pounded out xaudio in inetd.conf and the problem is now gone. 

Interestingly enough, this is the line in inetd.conf:

 

xaudio        stream   tcp              wait     root 

/usr/openwin/bin/Xaserver              Xaserver -noauth -inetd

 

The binary /usr/openwin/bin/Xaserver  does not exist on the box.  Not sure 

if that has something to do with it.

 

There are about 600 or so solaris 8 boxes, all with the same inetd.conf, all


with this problem.  I'm hoping xaudio was the problem.  They are servers, so


audio isn't needed.

 

 

----- Original Message ----- 

From: "Michel Arboi" <mikhail@nessus.org>

To: "Pete Duffin" <pduffin@blabbernet.net>

Cc: <nessus@list.nessus.org>

Sent: Thursday, July 12, 2007 4:40 PM

Subject: Re: Disable service identification

 

 

Le Thu, 12 Jul 2007 16:30:26 -0400,

"Pete Duffin" <pduffin@blabbernet.net> a écrit :

 

Do you recall if xaudio has ever been a problem with Nessus?

 

No.

 

I am convinced that your problem is the classical rate limitation on

inetd. Have you seen something like "telnet/tcp server failing

(looping), service terminated" on your console or in /var/log/messages?

 

Solaris is not uncommon and I'd be very surprised if a denial of

service against such a critical component would have been unnoticed

until now. 

 

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