Proof-of-Concept Evil Hotspot

So I recently built-out a new computer for the family common area, allowing me to repurpose that laptop for other nefarious tasks.  Ok, not really nefarious, i just wanted to have a decent test bed for trying out some of the latest versions of various flavors of Linux operating systems.  So the first one I'm trying is the newest Ubuntu, version 11.04.  One of the interesting capabilities that's been built into this OS for a couple of years now is Internet Connection Sharing whereby I can actually plug a device into the Ethernet port on my laptop and allow that device to piggy-back off of my laptop's existing Internet connection.  So of course I had to play around with it to see what I could do...

Enabling this functionality is actually extremely easy to do, and is well documented here.  Couple of screenshots to get the point across:

This functionality is extremely convenient in that it even pushes out a DHCP address to the connecting device.  So that's all well and good, but what can we DO with it?

Well, in my first blog post, I talked about how easy it was to spoof a legitimate hot spot's SSID, attwifi in my example, and some of the risks associated with connecting to those.  In my second post, I talked about Wireshark, and how easy it was to sniff traffic passing across the network to which you're connected.  Put 'em together and what have you got?  A method by which you can capture and view network traffic from mobile devices automatically connecting to you, trying to get Internet access.

Here's the setup: Internet connection --> Ubuntu laptop-Ethernet port --> WAN port-Asus WL-330GE Router-"Evil" attwifi network.

After you've configured Ubuntu to share out its Internet connection via the Ethernet port, and either rebooted or restarted the networking, your choice, you should find that the Internet-facing interface has reconnected back up, and the Ethernet interface will be ready to have a private address assigned to it, as per RFC 1918, once you plug in the router.  In my case, it was a 10.x.x.x address.

Now, plug in the wireless router's WAN port to the laptop's Ethernet port, and power up the router.  If it's configured to grab an IP address automatically via DHCP, it should also now have an IP address in the same subnet as the Ethernet interface of the laptop.  The wireless side of the router will now be broadcasting the new "evil" SSID, attwifi in my case.

Connect a "victim" device to the attwifi network, and you should find that you can get Internet access routed through the router --> laptop --> real Internet connection.  Now, run Wireshark on the Ubuntu laptop to capture clear-text traffic like http web traffic, smtp email traffic, telnet or ftp traffic, etc. sourced from your unwitting "victim" device.

One of the gotchas of running Wireshark on Ubuntu is that it will likely complain that there are no network interfaces to start capturing from.  This is because Wireshark needs root access to place those network interfaces into what's called "promiscuous mode," listening to all network traffic, not just that which is only intended for the system itself.  You can either "su" to root, or just "sudo wireshark" in order to get the necessary privileges to get Wireshark the access that it needs, and start capturing on the Ethernet interface of the laptop.  Done deal.

You also have the ability to do things like create a replica of a legitimate hot spot's captive portal to put up once someone connects to your "evil" one.  Then, you can capture a victim's hot spot credentials as well, in addition to their traffic once they've connected to you instead.  How easy is it?  Walk into a Starbucks, connect to their AT&T WiFi network, open up a browser, and when you get to their captive portal, from the File menu, just Save/Save Page As to pull down a copy of the site with all images and source code for your enjoyment.  Modify it to your liking, run it on your own webserver on the laptop, and you can even point to various Hotspot Services from the DD-WRT router firmware.

You can also have some more fun by creating a proxy on your laptop and causing some browsing mayhem doing something like serving up the Upside-Down-Ternet.  Watching the extremely confused looks on your victims' faces might actually be even more fun than just capturing their traffic and logon credentials, etc. :)

So the moral of the story hasn't changed, but let me summarize:

• Disable mobile device wireless when not in use.
• Be absolutely certain of what wireless networks you're connecting to and their legitimacy.
• Use encrypted protocols whenever possible.
• Don't do anything of a sensitive nature, like online banking or file transfers, when out and about using free, likely unsecured, wireless hotspots.

Like those Allstate commercials say, "Be better protected from mayhem like me.  Dollar for dollar, nobody protects you from mayhem like [gobitech]." :)

Wireshark - The Swiss Army Knife of Downloading Tools

In the Information Security industry, there are a wide variety of tools that can be used both for the forces of good and for evil.  One of these tools is called a packet sniffer which has the capability to listen in on the traffic passing along on the network that the system is connected to.  This can be extremely useful from a troubleshooting standpoint, or extremely dangerous as a vector of attack.  Over the last decade or so, most network environments have migrated from hubbed to switched, meaning network devices will only send traffic to the designated recipient system as opposed to blasting the traffic to all connected systems with the recipient system going, "Oh hey, that's meant for me."  This is definitely a good step for security, but also easily defeated with techniques like Address Resolution Protocol (ARP) poisoning, where an attacker can trick the network devices into sending traffic meant for someone else to them, listen in with a packet sniffer, and then forward the traffic along to the actual recipient.  This is accomplished by tricking both parties to update their ARP tables to map an IP address to an incorrect MAC address.  Another term for it is a Man-in-the-Middle attack.  One of the easier methods to do this is via a freely downloadable tool called Cain & Abel.  But I digress...

One of the absolute best packet sniffers available is another free tool called Wireshark.  This is a GUI tool with such an incredible amount of functionality built-in, that I feel like I'm still just starting to scratch the surface of everything that you can do with it.  I recently attended a SANS Voice-over-IP (VoIP) security course down in Orlando back in March where we were able to take a packet capture of network traffic and pull out the actual audio of bi-drectional calls that were being made with VoIP using this application.  Those of you using Vonage, magicJack, or any other consumer-grade VoIP product should probably be aware (or beware) that if you're on a shared network segment of any kind, e.g. cable modem, it's absolutely possible for someone to listen in on your conversations, capture touch tones (e.g. credit card numbers, PINS, etc.), and even listen to or inject audio into the conversation in real-time.  Scary stuff.

Anyway, enough with my security soap boxing, on to the good stuff.  Wireshark comes with the ability to pull files out of a network stream and save them out for later use.  Meaning you can fire up Wireshark, load up an mp3 in Grooveshark or a video in YouTube for example, and once it's done buffering, pull the file out of the packet capture, and listen to or watch that content as much as you want from your local hard drive, offline.  Intrigued yet?  First you'll need to download and install Wireshark.

1. Click on the link above, and download the latest stable release for your system's architecture, currently at version 1.4.6.  Launch the installer, click through a bunch of Nexts, and don't forget to install WinPcap which makes the magic happen.
2. Once it's installed, fire it up, and click on the first icon in the toolbar to "List the available capture interfaces..." Alternatively you can select Capture --> Interfaces from the menu.  Click the Start button next to the corresponding network connection that you want to listen in on.  Depending on your setup, there could just be one, but if not, typically it's the one that shows the most Packets passing through.
3. Now load up Grooveshark/YouTube, select a song/video, and wait for the buffering to complete.  You do NOT need to wait and listen to/watch the whole thing, but you do need for the whole thing to buffer up first.  Just the buffering is enough.
4. Once it's done buffering, in Wireshark, click on the fourth icon in the toolbar to "Stop the running live capture."  Alternatively you can select Capture --> Stop from the menu.
5. Now navigate to File --> Export --> Objects --> HTTP.  You will see a TON of files from different sites listed, but there's only one that you're interested in.  For a Grooveshark song, it should have a something.grooveshark.com Hostname, an audio/mpeg Content Type, a stream.php Filename, and likely it should be the largest in size (Bytes).  For a YouTube video, it should have something.youtube.com, video/x-flv, videoplayback?something, and should also likely be the largest in size listed.
6. Click on the entry, and you'll see a Processing window pop-up briefly and disappear.  Then click the Save As button in the lower right of the window.  Navigate to a location where you want to save the song/video and change it from stream.php to whatever-you-want.mp3 or for the YouTube video, whatever-you-want.flv.  Go ahead and play it.  You know you want to.  For the mp3s, you should find that any available meta-data came down with the file as well, like artist/song information, and album art.  For the videos, use whatever program you prefer to play flash videos.  I'm partial to VLC myself.

And now back to my soap box.  With tools like these that make eavesdropping on the network as easy as point-and-click, you really need to be aware of what you're doing on the Internet and what kind of security risks it comprises.  A few things to consider:

• Never click on links in your emails.  Yes, this is more of a piece of phishing advice, but those links could lead you to a fake version of a site that you thought you were clicking to which can capture your information with something like Wireshark, and then pass you on to the real site, without you ever realizing it.  It can be done, I've done it for a security awareness demonstration before.  Always type in the website address yourself and do your best to validate that it is properly secured with SSL (that little padlock that says communication between you and the site is encrypted, even though this too can be faked).
• Never give out sensitive information like your credit card number or PIN over the phone to someone that called you, especially if you're using consumer-grade VoIP at home.  There are even tools out there that can pull the corresponding numbers to (Wireshark) captured tone sounds, even if you never verbally spoke those numbers.  Always call the bank/credit card company directly yourself.
• If your work requires you to send files back and forth electronically with another party, make sure to use encryption on the connection (SSH/SFTP/SCP/SSL), on the file with a password (PGP/GPG/AES), or ideally both.  Now that you've seen how easy it is to pull a file out of the network stream when it's not encrypted, it should be obvious to you that protocols like Telnet/FTP/HTTP just aren't going to cut it anymore when it comes to security.

Anyway, I hope that this post has served both to educate, entertain, and horrify.  Until next time. :)