Some interesting events which happened in HarishRK's day-to-day life.
More focus is given towards ideas/inspirations/paradigm-shifts I experienced in day-to-day life.
In Hacking the main focus is over gathering the information about victim or victim's machine. Which will help to find out which type of exploit will works according to the given circumstances. Gathering the network and host information means to find out by which network, the which victim's machine is connected and communicating over the network. Moreover, scanning is also performed for gathering information about open and closed ports. After that they'll able to find the vulnerabilities in the target system and try to get access to the system.
Types Of Scan
As a CEH you should know the scan types and uses:
SYN
SYN scan doesn't complete the TCP three way handshake that is why it is known as a half-open scan. An attacker send a SYN packet to the victim machine if SYN/ACK packet is received back to attacker, then it clarify that the port is listening due to the acknowledgment by the victim that it has completed the connection. While if the attacker is received the RST/ACK packet then it assumed that the port is closed or open.
XMAS
XMAS scan works only on target system that has the RFC 793 development of TCP/IP and it doesn't works against any version of windows. XMAS scan send a packet with by setting up the FIN, URG and PSH flags of the TCP header. The function of this scan is if the port is active there will be no response but if the port is closed the target responds with a RST/ACK packet.
FIN
A FIN scan send a packet by setting up only the FIN flag of the TCP. This scan is similar to XMAS scan. FIN scan receives no response if the port is active while if the port is closed it receives the RST/ACK packet.
NULL
NULL scan is also similar to the XMAS scan. But the only difference is that it sends a packet without setting up the any flag of TCP header. NULL scan receives no response if the port is open but if the port is closed it receives the RST/ACK packet.
IDLE
It is just like spoofing an IP address by sending a SYN packet to the victim's machine to find out which services are available over the system. This scan is completed with the help of another system called as "Zombie" (that is not receiving or transmitting any information).
TL;DR, most of the security news about IoT is full of FUD. Always put the risks in context - who can exploit this and what can the attacker do with it. Most story only covers the latter.
Introduction
There is rarely a day without news that another "Internet of Things" got hacked. "Smart" safes, "smart" rifles, "smart" cars, "smart" fridges, "smart" TVs, "smart" alarm systems, "smart" meters, "smart" bulbs, NAS devices, routers. These devices are getting hacked every day. Because most of these devices were never designed with security as a goal, and some of them have been never tested by security professionals, it is no surprise that these things are full of vulnerabilities.
Independent security researchers find these vulnerabilities, write a cool blog post or give a presentation about the vulnerability and the exploit, and the media forgets the constraints just for the sake of more clicks. "We are all doomed" we can read in the news, but sometimes the risks are buried deeply in technical jargon. Please note I blame the news sites here, not the researchers.
There are huge differences between the following risks:
Attackers can directly communicate with the router (or camera) from the Internet without authentication and exploit the vulnerability. This is the worst-case scenario. For example, an automated ransomware attack against your NAS is pretty bad.
Attackers have to position themselves in the same WAN network (e.g. Sprint mobile network in the case of Jeep hacking) to exploit the vulnerability. This is still pretty bad.
The vulnerable code can not be triggered directly from the Internet, but tricks like CSRF can be used to exploit it (details later in this post).
The vulnerable code can not be triggered directly from the Internet, and it uses a protocol/port which prevents Cross Protocol Scripting. Attackers have to access the local network before exploiting this vulnerability.
Most devices are behind an IPv4 NAT device (e.g. home router), thus can not be reached from the Internet side by default. Except when the device configures the firewall via UPNP. Or the device has a persistence cloud connection, and the cloud can send commands to the device. Or the device uses IPv6 tunneling (e.g. Teredo), thus it is reachable from the Internet. But not every vulnerability on your home network is accessible directly from the Internet. As more and more devices and networks will support IPv6, this scenario might change, but I hope most home routers will come with a default deny configuration in their IPv6 firewall module. On the other hand, scanning for IPv6 devices blindly is not feasible due to the large number of IPv6 addresses, but some tricks might work.
If attackers can not access the device directly, there is a way to hack it through the user's browser. Just convince the victim user to visit a website, and via CSRF (Cross Site Request Forgery) and brute-forcing the device IP, it is possible to hack some devices (mostly through HTTP - if the exploit can fit into simple GET or POST commands.
If attackers can not attack the device vulnerability through the Internet directly, or via CSRF, but have connected to the same network - the network exposure shrinks significantly. And when attackers are on the same network as you, I bet you have bigger problems than the security of the IoT devices ...
Recommendations for home users
Don't buy **** you don't need
Disconnect from the power cord the IoT devices you don't need to operate 7*24.
Disable cloud connectivity if it is not necessary. For example, I have a NAS device that can be reached through the "cloud", but I have disabled it by not configuring any default gateway for the device. I prefer connecting to my network via VPN and reach all my stuff through that.
Prevent CSRF attacks. I use two tricks. Don't use the 192.168.0.x - 192.168.10.x network at-home - use an uncommon IP range instead (e.g. 192.168.156.x is better). The second trick is I configured my Adblock plugin in my primary browser to block access to my internal network. And I use another browser whenever I want to access my internal devices. Update: On Firefox you can use NoScript ABE to block access to internal resources.
Check your router configuration:
disable UPnP
check the firewall settings and disable unnecessary port forwards
check for IPv6 settings, and configure the firewall as default deny for incoming IPv6 TCP/UDP.
Run Nmap to locate new IoT in your home network :)
Run a WiFi scan to locate new WiFi access points. Let me share a personal experience with you. I moved to a new house and brought my own WiFi router with me. I plugged it in, and forget about WiFi. Months later it turned out I had two other WiFi devices in my house - the cable modem had its own integrated WiFi with default passwords printed on the bottom, and the Set-top-box was the same - default WiFi passwords printed on the bottom. And don't forget to scan for ZigBee, Bluetooth, IrDA, FM, ...
Update your devices - in case you have a lot of free time in your hand.
Don't allow your guests to connect to your home network. Set up a separated AP for them. Imagine your nephew stealing your private photos or videos from your NAS or DNLA server.
With great power, comes great responsibility. The less device you own in your house, the less time you need to maintain those.
Read the manuals of your devices. Be aware of the different interfaces. Configure it in a secure way.
Disable Teredo protocol in case you don't need IPv6.
Update: Prevent against DNS rebind attacks via configuring a DNS server which can block internal IP addresses. OpenDNS can block internal IP, but this is not a default option, you have to configure it.
Recommendations for vendors
For vendors, I recommend at least the followings:
Implement security during Software Development LifeCycle
Continuous security testing and bug bounties
Seamless auto-update
Opt-in cloud connectivity
Recommendations for journalists
Stop FUD. Pretty please.
The questions to ask before losing your head
who can exploit the vulnerability?
what prerequisites do we have about the attack to successfully exploit the vulnerability? Is the attacker already in your home network? If yes, you have probably bigger problems.
what can the attacker do when the exploit is successful?
And last but not least, don't forget that in the case of IoT devices, sometimes users are the product, not the customer. IoT is about collecting data for marketing purposes.
YardStick One Unleashed, Automating RF Attacks In Python - An RFCat Primer
I decided to dive into our current device a bit more before moving on to a new device, and really ramp up the skillsets with RFCat and the Yardstick.So for this blog you will need our previous Target and a Yardstick One. We will be hacking everyting using only the Yardstick and Python.
So last time we scanned for signals with GQRX and a Software Defined Radio device. We took the demodulated wave forms in Audacity and discerned what the binary representation of our wave forms were by decoding them manually. We then transferred those into a hex format that our yardstick understood.However there is a way to do everything with our Yardstick. It will require a bit more understanding of the RFCat library, and a bit of python.
This blog will be your RFCAT primer and coding tutorial, but don't be scared with the word "Programming" I will be using simple code, nothing complicated.So if your a programmer, tune out any coding explanation and understand RFCat, if your not a coder, then use this as a jumping point to start making some quick python scripts for hacking.
Video Series PlayList Associated with this blog:
The first thing we did in our last blog after looking up the frequency was to open up GQRX and check if we can see our devices signals. As it turns out you can actually do this in python with RFCat. Which is really convenient if you left your Software Defined Radio dongle at home but happen to have access to a Yardstick.
RFCat as a Spectrum Analyzer:
In order to use RFCat as a spectrum analyzer we need to make sure we have RFcat installed and a few prerequisites such as python and PySide modules.I actually did this inside of an Ubuntu VMware because Pyside was giving me issues on OSX and I didn't feel like trying to fix it. So If you spin up an ubuntu vm you can do the following to get things up and running..
Install Spectrum Analyzer PreReqs:
sudo pip install PySide
sudo apt-get install ipython
Plug in your adapter and type in the following:
rfcat -r
d.specan(315000000)
You will then see the below output of RFCat Specan running in the 315 MHz range.
Click our doorbell, or trip the motion sensor and you will see a frequency spike as shown in the second picture.
This is similar to what you saw in GQRX but all with your Yardstick and the Python RFCat library.
So everything seems to be working and we can see our devices transmitting on the 315MHz frequency.Unfortunately we have no record button on Spescan. This leaves us to dive a little deeper into RFCat. We will see what RFCat can do for us in the recording and sniffing capacity.
Sniffing RF Data With The YardStick and Python:
In RFCat there is a simple listening command in our interactive session which will give us an idea of what is being transmitted and in what type of data format we are recieving. When using GQRX we received a WAV file, but what does RFCat give us?One thing I have realized over the years is programming is all about dealing with data in various formats and figuring out how to parse and use it in various implementations. So the first thing we have to figure out is what kind of data we are dealing with.
Lets hop back into RFCat and set a few parameters so the yardstick knows to listen on 315MHz and to use ASK modulation.The settings below should all be familiar from our last blog with an exception of "lowball" which configures the radio to use the lowest level of filtering. We basically want to see everything but may experience some noise by not filtering it out.. For example before you hit your doorbell button you may see random FF FF FF FF data outputted to the screen.
Below is the cmdline input needed and some example output. After all of our settings are in place we can use RF.listen() to start listening for everything in the 315000000 frequency range and have it output to the screen.
After you set it up, you can press the button on your doorbell and you will receive the following output. We have lots of zeros and what might be some hex output.
Destroy ficti0n$rfcat -r
>>> d.setFreq(315000000)
>>> d.setMdmModulation(MOD_ASK_OOK)
>>> d.setMdmDRate(4800)
>>> d.setMaxPower()
>>> d.lowball()
>>> d.RFlisten()
Entering RFlisten mode...packets arriving will be displayed on the screen
If you hit "ENTER" in your terminal you will stop receiving packets and drop back into a python interactive terminal. If we take a look at the repeating pattern in the above output, it looks like some random patterns and then a repeating pattern of, 84e708421084e738.If we convert that to binary we can compare with what we decoded WAV from our previous blog.
Since we are already in a python terminal you can type the following to see the binary representation:
Lets break that up into 8 bit bytes and compare it to our previous blogs binary, hmm its lot different then what we originally decoded the signal to be:
If we take the above capture data and format it correctly for RFcat with the replay code from the last blog. When we send it over, it does indeed ring the doorbell, thats interesting. A completely different value in both hex and in binary and still we get a doorbell to ring. So the variance we talked about last time extends a bit more. Below is the code with the new hex from the capture data:
I will also take a minute to note something before we continue. I had a little trouble at first when using a telescopic antenna in RFcat and the YardStick.So I will list those issues below as notes for you to play with if you run into random looking captures when pressing your doorbell button.
When using a telescopic antenna closed I had almost repeating output with some random bits flipped
When extending the antenna it went crazy output with random noise
I then used a small rubber ducky antenna and got the repeating output shown above.
What we have done so far:
So above, we managed to figure out the following all in RFCat
Verify the frequency with RFCat
How can I listen for it and capture a transmission with RFCat
How can I send this transmission with RFCat
We have basically eliminated the immediate need for the graphical tools that we were using in the last blog. Not to say that they are not useful. They absolutely are, and we should use them often and know how to work with all kinds of formats and understand everything.. However, if we are living in a reality that all we have is a Yardstick and no other tools. We are not helpless and we can still kick some serious RF butt.
Now we are going to take this a bit further so we can learn some more about RFCat, Python and mistakesI made when trying to automate this stuff. I found some interesting quirks I had to work through and I would like to save others some time who are also in the learning process as I am.
Using RFrecv() for Listening:
Ok first thing I learned is that RFListen() is not all that useful when it comes to automating this stuff. I tried to set its output to a variable but that did not seem to work.. So instead we will be working with another feature that lets us listen and that is RFrecv().If we fire up our RFCat in the terminal again we can give that a try:
Destroy:~ ficti0n$ rfcat -r
>>> d.setFreq(315000000)
>>> d.setMdmModulation(MOD_ASK_OOK)
>>> d.setMdmDRate(4800)
>>> d.setMaxPower()
>>> d.lowball()
>>> d.RFrecv()
Traceback (most recent call last):
File "", line 1, in
File "/Library/Python/2.7/site-packages/rflib/chipcon_nic.py", line 1376, in RFrecv
data = self.recv(APP_NIC, NIC_RECV, timeout)
File "/Library/Python/2.7/site-packages/rflib/chipcon_usb.py", line 664, in recv
raise(ChipconUsbTimeoutException())
ChipconUsbTimeoutException: Timeout waiting for USB response.
OK thats not cool we are getting a weird error if we don't get a signal right away regarding ChipconUsbTimeoutException.
No problem since we are in a python terminal we can just capture this exception and pass it, then continue with sniffing.This is done with a Try/Except block.
try:
... d.RFrecv()
... except ChipconUsbTimeoutException:
... pass
...
That looks a little better, I am no longer receiving errors, but lets put this in a loop so we are continuously listening with RFrecv() and press our doorbell so we can capture our doorbell signal.Below is the output of a random signal that came in followed by our doorbell.. but its all kinds of crazy looking and a bit hard to read:
try:
... d.RFrecv()
... except ChipconUsbTimeoutException:
... pass
...
while True:
... try:
... d.RFrecv()
... except ChipconUsbTimeoutException:
... pass
Lets try to fix the output a little and make it more readable by encoding it before we view it. Open up your text editor and use the following code.What we are doing here is simply setting up our listener as we did before and then setting it to a variable we can use.
Line 12: Setting our RFrecv() output to the variable y and z. The y variable is the output that we want
Line 13: We will wrap the y variable with an encode function to encode it with a HEX encoding.
Line 14: After that we just print it out.
When we run this script from the command line we will get a much nicer output shown below, much like we did with the RFlisten function above. The big difference being that our data is now set to the variable "capture"on line 13 and we can do what we want with that data. For example we can directly replay that data rather then manually performing the actions.
Parsing and replaying data:
This actually took me a bit of time to figure out, so we need to do a few things to get this to work:
We need to parse out the data from the surrounding 0s
We need to convert it to a format we can send (tricker then it sounds)
We need to add padding and send that data over (We know how to do this already)
Parsing Data:
So with this I first tried all kinds of regular expressions, but for some reason the inverse of more then 3 zeros in a row does not seem to work. I am no regex master but that seemed like it should be working. I then tried a few creative solutions reducing repeating zeros down to pairs that I could split on with string functions. This actually worked well but then my buddy showed me this which was more efficient:
re.split ('0000*', capture)
All this is doing is using the regex library to parse on a set of 4 or more zerosand return whats left in a list of useable hex data for sending.So lets add that into our code and give it a try to see what we get back. I made the following code changes:
Line 2: Import the Regex library
Line 11: We defined the capture variable so we can access it outside of the Try Block and the loop
Line 21: We created a payloads variable and created a list from the capture file of non 0000 blocks
Line 22: We print out our list of useable payloads which can been seen in the below output
Data Format Woes:
So we have data in a list we can pull from, thats awesome but I ran into a few issues. I first tried to parse this data into the \x format we normally used when sending our attack payloads manually, but that actually does not work. Reason being that if I use a code snippet like the following to convert this data into the right format everything looks ok and something like this \x84\xe7\x08\x42\x10\x84\xe7.But it won't actually work when I send it with RFCat. For some reason when you paste in your own hex its in a different format then if you programmatically create hex like below. You don't really need to understand the code below, just know it takes our payload and creates the hex in a visual format to what we used in the last blog:
DON'T USE THIS.. IT WONT WORK!!!
for payload in payloads:
formatted = ""
if (len(payload) > 6) and (len(payload) % 2 == 0):
print "Currently being formatted: " + payload
iterator = iter(payload)
for i in iterator:
formatted += ('\\x'+i + next(iterator))
else:
continue
Formatted Hex Vs Manually Pasted Hex
So lets compare the outputs of our manually created Hex String versus what we get when we format with the above code
Below is the output of the following:
Your encoded capture
Your parsed payloads in a nice list
Your payload being processed into hex.
But this is where things go wrong, you then have :
Your nicely formatted Hex created by your code above (Yay for us)
Then you have your manually pasted in hex from your original attack payloads as unprintable characters(What?)
You can clearly see there is a major difference between when we manually paste in our hex like we did in the last blog and when we create it from our capture file.This led to another sleepless night of researching whats going on. I did a bunch of troubleshooting until I found some code on the RFcat site and saw it using the BitString library and something called BitArray.The examples for this library were using binary data instead of hex and then converting it.
BitString BitArray Formating FTW:
If you remember above we created binary input with some python, so lets use that code in our current program template and then feed it into byteArray and see what happens. We can install bitstring with the following:
Install Bitstring:
sudo pip install bitstring
Our New code using BitString:
Line 2: I imported bitstring
Line 25: I added a for loop to go through our payload list one by one
Line 27: I convert our current payload to binary
Line 28: I take that binary and I feed it into bitstring to fix the formatting issues
Lines 29-30:Print out our binary and our new data that match our manually pasted data format, shown below
With these conversions the data above looks like its correct to attack our target devices. I know this seems like a lot of steps, but honestly this is only 50 lines of code in all to automate our replay attacks in a simple way.It is also very easy if you know what your doing and don't spend all of your time figuring it out like I did. You just need to understand how to work with the types of data each component understands.
With this latest code update we are ready to send our code with a simple modification to our RFxmit line from the last blog. We will now change RXxmit to take our formatted variable and then append our padding:
Below is our full code to automate this attack, with a few changeups, but not many.. Really all I did was add some conditional statements to limit our data to longer payloads that are divisible by 2 since our hex takes 2 string characters for example \x41 is the string character 4 and 1.I originally did this for the iterator code which required the proper amount of characters but decided to leave it since it makes sense anyway.I also set it so that if there is a capture it breaks out of the loop. This way we are not continuously attacking every transmission we see. Instead for our testing we can hit our doorbell, replay all the values before our script finishes and exits.
Note: I sent similar code to a friend and had him run it against a black box real world target. He had permission to attack this target via the owner of a facility and it worked flawlessly. So although a doorbell is a trivial target. This same research applies to garages, gates, and any other signal not using protection mechanism such as rolling code, multiple frequencies at once etc.
Also note that when you run this, almost all of the payloads in your list will ring the doorbell which is why I put a timing variable before the sending command. This way your doorbell isn't overburdened. I already broke a few of these devices during testing LOL.
I have since modified this code to be more effective, and have additional features and more niceties, I will release that code when its ready.. For now enjoy the below code and hit me up with any questions or comments.
I hope this blog is helpful in demystifying RFCat in order to successfully perform/automate attacks with only Python and your Yardstick One. This is essentially a few nights of my research posted here for everyone to learn from. Because it was a pain to find useful information, and I would like to save other people a lot of sleepless nights. I am by no means the master of RF or RFCat, there is tons more to learn. Up next I will get back on track with a real world attack against a device and creating our own keyfobs to replay our attacks in the future.
