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RE: In secured office building, "Free Public WiFi" network shows up out of nowhere
From: <jbeauford () EightInOnePet com>
Date: Thu, 21 Jun 2007 09:24:59 -0400

Free Public Wifi's show up when your laptop connects to an Ad Hoc network.  Essentially it configures itself as a 
relay.  Consider it like a wifi "worm".  It's everywhere.  You should configure your laptops to connect to AP's only, 
no Ad Hoc.

Here's some info:



-----Original Message-----
From: listbounce () securityfocus com [mailto:listbounce () securityfocus com] On Behalf Of Scott Ramsdell
Sent: Wednesday, June 20, 2007 12:07 PM
To: Kurt Buff; Shawn
Cc: security-basics () securityfocus com
Subject: RE: In secured office building, "Free Public WiFi" network shows up out of nowhere

If they are Windows based, and on your domain, then likely they registered their AIPAI IP with your DNS server via 
DDNS.  You may be able to find your hostname there.

Kind Regards,
Scott Ramsdell
Security Network Engineer

-----Original Message-----
From: listbounce () securityfocus com [mailto:listbounce () securityfocus com] On Behalf Of Kurt Buff
Sent: Tuesday, June 19, 2007 5:26 PM
To: Shawn
Cc: security-basics () securityfocus com
Subject: Re: In secured office building, "Free Public WiFi" network shows up out of nowhere

I would have gone a bit further.

Since you probably don't have access to the machines in the training
center I would start to cultivate a relationship with whomever their
IT person is, and get to the point of asking, gently, politely, if
they indeed have a wireless access point fired up.

However, I would assume that you have root/administrator privileges on
all workstations in the spaces your company occupies (though perhaps
not all servers - that would depend on your security policy.) Assuming
they are Windows-based I would have run PSEXEC against them to find
out their network setup, using 'ipconfig /all' and 'route print' to
extract details of their network interfaces, etc.

Also, I would have gathered all of the arp caches and MAC address
tables from your network devices to verify that the machine in
question isn't directly attached to the network.

Lastly, highly-directional antennas are your friend. They're cheap, too.


On 6/19/07, Shawn <swarzkopf () legolas sinnerz us> wrote:
This scenario occurred this morning- any suggestions or insights are
appreciated, as are any comments as to my handling of this.

I'm a Security Specialist for a medium sized company. I have only
been working in security for 2 months. There are no other
Security Specialists here. I report to our Manager of Information
Security, who is out of town on business. I work in a 6 floor office
building which we own completely. We lease the second floor to a computer
training center. We do not permit our employees to use any wireless
networks, and we do not have any access points. Ad hoc connection is
prevented through group policy. All of our laptops are XP SP2. Up until
today, I have never seen an available wireless network here.

Periodically I check to make sure that no one has installed an
unauthorized WAP. This morning I fired up NetStumbler and found that a
network named "Free Public WiFi" was not only available, but available at
full strength. This was listed as a peer to peer network, so I assumed
that the network was actually being broadcast from another wireless device
(laptop). This network was listed as being wide open with no required key
and no encryption. The originating point definitely appears to be coming
from within my building, but I haven't been able to determine exactly

I immediatley checked the MAC address of the wireless SSID to make sure
that it didn't belong to one of my company assets. It did not.

I then connected to the network with my laptop. I was not assigned an IP
address, rather Windows gave me one of the default 169.254 APIPA
addresses. I then
sniffed packets for over an hour. I felt justified in doing this, to make
sure that none of my companies equipment was connecting to this network.
I found no network activity whatsoever.

Finally, I ran a ping sweep against the 169.254.x.x subnet to make sure
that none of my companies equipment were connected to this network. The
ping sweep returned only my laptop and one other device. I checked the
other device's MAC address in my inventory and verified that it too was not our

I then summarized all of my investigation and sent it to my boss in an
email. I suggested that this network does not appear to be malicious at
this time and offered to take more action pending his recommendation. I
believe that this network probably belongs to someone at the computer
training center on our second floor playing around.

Do you all feel that these were appropriate actions? The only other
possible action I considered regarding this would be to contact the
training center on the second floor and ask them about this. What do you
all think?

As always, your feedback is appreciated.


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