Great Circle Associates Firewalls
(April 1995)
 

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Subject: Re: How to detect SATAN surfing attempts ?
From: paul @ hawksbill . sprintmrn . com (Paul Ferguson)
Date: Mon, 3 Apr 1995 21:47:35 -0500 (EST)
To: romig @ net . ohio-state . edu (Steve Romig)
Cc: vds7789 @ aw101 . iasl . ca . boeing . com, firewalls @ GreatCircle . COM
In-reply-to: <199504032006 . QAA29850 @ bedbugs . net . ohio-state . edu> from "Steve Romig" at Apr 3, 95 04:06:29 pm

This is pretty simple stuff.

In fact, most of it is really old, simple stuff.

In any event, it looks like satan is nothing more than ISS with
a motif, but I'm sure we'll all get a better feel for 'it' after
the 5th. I've already had an opportunity to tinker with the
pre-release, and I can assure you it's not as devastating as
the popular press would depict it. Can you say 'hype'?

[sorry for the lengthy quote]

- paul


> 
> Here's a rough outline about what Satan does, for those who may be
> trying to detect this sort of stuff.
> 
> subnet scan
> 
>   when it probes a subnet, it runs fping to see what hosts are there.
>   fping sends ICMP echo request packets to a bunch o'hosts and waits
>   for the replies.  its faster than ping since it doesn't wait for the
>   reply for one before sending the request to the next.  satan calls
>   this as 'fping NET.1 NET.2 NET.3 ...NET.255', so when satan probes a
>   subnet you should see icmp echo requests for increasing IP
>   addresses, starting at 1 (regardless of the real subnet mask, btw,
>   satan assumes class c subnet masks).
> 
> host scan
> 
>   when it probes a host, i have no idea what order it goes in.  i
>   don't think that its set - it might change from host to host, and it
>   is fluid in that some tests don't get done on every host (eg, if it
>   isn't running nfs, it won't test certain nfs things).
> 
>   minimal scan
> 
>   at the very least, when a host is being probed it will do the dns,
>   rpc and showmount probes.
> 
>     the dns probe looks up the name/ip address and reads the output of
>     "nslookup / set qt=any / $target".  It squirrels away info like
>     the mail exchange host, name servers for the domain, and HINFO
>     records.
> 
>     the rpc probe does "rpcinfo -p $target" to see what rpc services
>     are listed.  far as i know, it just saves the data, doesn't
>     immeadiately do anything on the net.
> 
>     the showmount probe does "showmount -e $target" to see what other
>     hosts can mount from the target, and then runs "showmount -a
>     $target" to see who has mounted what from the target.
> 
>   heavy scan
> 
>   at the highest level, it will optionally use an rusers scan (if
>   rpcinfo showed that the rusers service was registered), a bootparam
>   scan (if registered), finger, and a normal and heavy tcp and udp
>   port scans.  
> 
>   the tcp and udp scans do the following in order:
> 
>     normal tcp: 70, 80, ftp, telnet, smtp, nntp and uucp
>     normal udp: 53, 177
>     heavy tcp: 1-9999
>     heavy udp: 1-2050,32767-33500
> 
>   the tcp scanner tries to connect to each port in turn, when it
>   connects, it sends 'QUIT\r\n' and closes the connection.  the udp
>   scanner sends a 0 byte.
> 
> So, when satan scans a subnet you will see ICMP echo requests to hosts
> NET.1, NET.2 through NET.255.  When satan scans a host, at a bare
> minimum, you will see the "rpcinfo -p" call to the portmapper on the
> target, and the "showmount -e" and "-a" calls to the mountd on the
> target. 
> 
> You can't depend on seeing more than that, since some tests (like tcp
> and udp port scans) will only be done at high scanning levels, and
> others (like rusers and boot) will only be done if those services were
> listed with the portmapper on the target.
>

 
_______________________________________________________________________________
Paul Ferguson                         
US Sprint                                          tel: 703.689.6828
Managed Network Engineering                   internet: paul @
 hawk .
 sprintmrn .
 com
Reston, Virginia  USA                             http://www.sprintmrn.com 


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