[FLASHER] [v1.3 - 2014-07-07] FlashCast: Quickly and easily mod your Chromecast

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tchebb

Inactive Recognized Developer
Jul 28, 2010
189
242
tchebb.me
VaHvwVY.png


What is it?

FlashCast is a USB image that provides a standardized way to mod your Chromecast. Think of it like a recovery which runs off of a USB drive. No more struggling with the limitations of the GTVHacker image, which is hard to modify and can only flash the /system partition. FlashCast is based on shell scripts, so it you can use it to do anything you can do with a root shell. It also comes with a comprehensive suite of helper functions, so many tasks actually become much easier than they would be using a regular shell.

How do I use it?

If you prefer to follow a video tutorial, @ddggttff3 has made one here. Otherwise, read on for written instructions.

Preparation

Before you begin, you'll need some materials:
  • A Chromecast with a vulnerable bootloader. (For the bootloader to be vulnerable, the Chromecast must have never been connected to the internet and have a rootable serial number.)
  • The latest version of FlashCast (the download link is at the bottom of this post).
  • A USB drive (minimum size 256MB) which you are willing to have erased.
  • A powered Micro-USB OTG cable such as this one. (Alternatively, an unpowered USB hub and unpowered OTG cable can be used as shown here. I have not tested this method and cannot help you if your USB drive is not detected.)

Installation

Once you've gathered everything required, you can install FlashCast to your USB drive. To do so, you need to write the .bin file contained in the FlashCast .zip file you've downloaded to your drive. Simply using a file explorer to drag the .bin file to your USB drive is not correct and will not work. The specifics of doing a low-level write differ depending on OS, but, in general, Linux and OS X users should use dd and Windows users should use Win32DiskImager. This operation will erase your flash drive.

After you've written the .bin file to your USB drive, your computer will no longer recognize a filesystem on it. This is normal. In order for FlashCast to set up the drive's filesystem, you need to boot your Chromecast from the drive. To do this, perform the following steps:
  1. Connect the male end of your Micro-USB OTG cable to your Chromecast.
  2. Plug your USB drive into the USB-A female connector of the OTG cable.
  3. Simultaneously hold the button on your Chromecast and connect the Micro-USB power connector to the female Micro-USB port of the OTG cable.
The power must be connected last. If it is not, your Chromecast may fail to detect the USB drive and boot up normally. If this happens, simply repeat the process, making sure to perform the steps in the correct order.

If FlashCast was copied correctly, you will see a red light on your Chromecast for approximately 9 seconds. It will then turn white and your TV will display a screen containing the FlashCast logo (shown at the top of this post) and various instructions. Once you see this screen, you may release the button. The screen will appear for another 9 seconds or so, after which your Chromecast will reboot on its own to the stock image. After it has rebooted (you may disconnect the power when it starts to boot into the stock image if you're worried about it updating), FlashCast is installed on your USB drive and ready for use. Your device is NOT rooted at this point and can still be updated by Google. To root, you need to flash a mod such as Team Eureka's Eureka-ROM. When you plug the drive into your computer, it should appear as an empty drive which you can copy files to.

Usage

FlashCast-compatible mods are distributed as .zip files. To flash a mod, simply copy it to the USB drive with the name eureka_image.zip. Do NOT use dd as you did in the previous section. If you do, you will have to repeat the whole process. Instead, just copy it onto the drive's filesystem as you would any other file. FlashCast is also capable of flashing a GTVHacker-style raw system image; if there are no native FlashCast mods present and the system image is in a file called Chromecast-Rooted-System-GTVHacker-cj_000-July27-635PM.bin, it will be flashed. This method of flashing is very inflexible and is not recommended.

How do I develop for it?

If you are interested in creating mods for FlashCast, please see the developer thread.

Who made it?

FlashCast is based on a generic Buildroot Linux image. Its mod framework was written entirely by me, but I couldn't have done it without the help of various individuals. Thanks, @cj_000, for helping me and putting up with my stupid questions in IRC. And thank you, @tvall, for releasing your update-free images so promptly up until now. Without those, FlashCast would have a much smaller potential user base.

Where do I get it?

Downloads and source code are available at FlashCast's GitHub repository. The latest version is currently v1.3.
 
Last edited:

cj_000

Member
Aug 2, 2013
6
11
tchebb, awesome work. Your flasher seems so much more flexible than what we put out (but hell, we did it in 3 days), and it's never a problem to help out. In fact, we LOVE it when someone actually picks up on what we did and makes it so much better.

Can't wait to give it a try, once I get some free time!

CJ
 
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twist

Senior Member
Feb 23, 2006
512
85
Looks super cool man, I am about to check it out and update my chromecasts now! Great work!!
 

tchebb

Inactive Recognized Developer
Jul 28, 2010
189
242
tchebb.me
How do I know if I have A Chromecast with a vulnerable bootloader ?

The initial software which the Chromecast shipped with, build 12072, had a vulnerable bootloader. In all following software versions (12840, 12940, and 13300), the vulnerability is patched and FlashCast can't be used. If your Chromecast has been allowed to access the internet, it will have updated itself and will not be vulnerable. If you have not set up your Chromecast and it still has the software from the factory, it may or may not be vulnerable, depending on when you bought it. To check, you can plug it in (but not set it up), and check its "Build" in the Chromecast app. Alternatively, you can simply try to boot FlashCast on it. If it's patched, nothing bad will happen; the USB drive will simply fail to boot.
 

twist

Senior Member
Feb 23, 2006
512
85
The initial software which the Chromecast shipped with, build 12072, had a vulnerable bootloader. In all following software versions (12840, 12940, and 13300), the vulnerability is patched and FlashCast can't be used. If your Chromecast has been allowed to access the internet, it will have updated itself and will not be vulnerable. If you have not set up your Chromecast and it still has the software from the factory, it may or may not be vulnerable, depending on when you bought it. To check, you can plug it in (but not set it up), and check its "Build" in the Chromecast app. Alternatively, you can simply try to boot FlashCast on it. If it's patched, nothing bad will happen; the USB drive will simply fail to boot.

I just got 2 units this week from Amazon and they have not been updated from the factory and thus, vulnerable.
 
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raydekok

Senior Member
Mar 16, 2009
455
37
Amersfoort
The initial software which the Chromecast shipped with, build 12072, had a vulnerable bootloader. In all following software versions (12840, 12940, and 13300), the vulnerability is patched and FlashCast can't be used. If your Chromecast has been allowed to access the internet, it will have updated itself and will not be vulnerable. If you have not set up your Chromecast and it still has the software from the factory, it may or may not be vulnerable, depending on when you bought it. To check, you can plug it in (but not set it up), and check its "Build" in the Chromecast app. Alternatively, you can simply try to boot FlashCast on it. If it's patched, nothing bad will happen; the USB drive will simply fail to boot.

damm, i have this 13300 version. and this will never happen or is there a way?
 

twist

Senior Member
Feb 23, 2006
512
85
I just finished using FlashCast on 2 ChromeCasts and everything went smooth and great! I could really see FlashCast evolving into a full blown recovery for ChromeCast!

I am thoroughly impressed with FlashCast, amazing work man, well done!
 
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siratfus

Senior Member
Dec 28, 2011
63
13
Hey guys, what's the purpose of this? Does it mean we can then use 3rd party developed apps? Apps that allow us to play local videos, etc.?
 
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stewwmann

Senior Member
Feb 2, 2013
203
42
San Diego
Thank You, Thank You very much....

Thanks for all the responses, I found a local Best Buy that has one, and I have put it on in store pickup for tomorrow. So if I do end up with one that has original fw, and am successful in installing flashcast, I can use the device as normal after that? no worries of it being locked back down? if we are not sure ,I just will continue using my updated one until then
 

tvall

Senior Member
Oct 10, 2010
2,230
792
29
Springfield
Thanks for all the responses, I found a local Best Buy that has one, and I have put it on in store pickup for tomorrow. So if I do end up with one that has original fw, and am successful in installing flashcast, I can use the device as normal after that? no worries of it being locked back down? if we are not sure ,I just will continue using my updated one until then

If it comes with the original version, and you install an image that doesn't update, you can use it as normal and not worry about it being locked down.
 

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    VaHvwVY.png


    What is it?

    FlashCast is a USB image that provides a standardized way to mod your Chromecast. Think of it like a recovery which runs off of a USB drive. No more struggling with the limitations of the GTVHacker image, which is hard to modify and can only flash the /system partition. FlashCast is based on shell scripts, so it you can use it to do anything you can do with a root shell. It also comes with a comprehensive suite of helper functions, so many tasks actually become much easier than they would be using a regular shell.

    How do I use it?

    If you prefer to follow a video tutorial, @ddggttff3 has made one here. Otherwise, read on for written instructions.

    Preparation

    Before you begin, you'll need some materials:
    • A Chromecast with a vulnerable bootloader. (For the bootloader to be vulnerable, the Chromecast must have never been connected to the internet and have a rootable serial number.)
    • The latest version of FlashCast (the download link is at the bottom of this post).
    • A USB drive (minimum size 256MB) which you are willing to have erased.
    • A powered Micro-USB OTG cable such as this one. (Alternatively, an unpowered USB hub and unpowered OTG cable can be used as shown here. I have not tested this method and cannot help you if your USB drive is not detected.)

    Installation

    Once you've gathered everything required, you can install FlashCast to your USB drive. To do so, you need to write the .bin file contained in the FlashCast .zip file you've downloaded to your drive. Simply using a file explorer to drag the .bin file to your USB drive is not correct and will not work. The specifics of doing a low-level write differ depending on OS, but, in general, Linux and OS X users should use dd and Windows users should use Win32DiskImager. This operation will erase your flash drive.

    After you've written the .bin file to your USB drive, your computer will no longer recognize a filesystem on it. This is normal. In order for FlashCast to set up the drive's filesystem, you need to boot your Chromecast from the drive. To do this, perform the following steps:
    1. Connect the male end of your Micro-USB OTG cable to your Chromecast.
    2. Plug your USB drive into the USB-A female connector of the OTG cable.
    3. Simultaneously hold the button on your Chromecast and connect the Micro-USB power connector to the female Micro-USB port of the OTG cable.
    The power must be connected last. If it is not, your Chromecast may fail to detect the USB drive and boot up normally. If this happens, simply repeat the process, making sure to perform the steps in the correct order.

    If FlashCast was copied correctly, you will see a red light on your Chromecast for approximately 9 seconds. It will then turn white and your TV will display a screen containing the FlashCast logo (shown at the top of this post) and various instructions. Once you see this screen, you may release the button. The screen will appear for another 9 seconds or so, after which your Chromecast will reboot on its own to the stock image. After it has rebooted (you may disconnect the power when it starts to boot into the stock image if you're worried about it updating), FlashCast is installed on your USB drive and ready for use. Your device is NOT rooted at this point and can still be updated by Google. To root, you need to flash a mod such as Team Eureka's Eureka-ROM. When you plug the drive into your computer, it should appear as an empty drive which you can copy files to.

    Usage

    FlashCast-compatible mods are distributed as .zip files. To flash a mod, simply copy it to the USB drive with the name eureka_image.zip. Do NOT use dd as you did in the previous section. If you do, you will have to repeat the whole process. Instead, just copy it onto the drive's filesystem as you would any other file. FlashCast is also capable of flashing a GTVHacker-style raw system image; if there are no native FlashCast mods present and the system image is in a file called Chromecast-Rooted-System-GTVHacker-cj_000-July27-635PM.bin, it will be flashed. This method of flashing is very inflexible and is not recommended.

    How do I develop for it?

    If you are interested in creating mods for FlashCast, please see the developer thread.

    Who made it?

    FlashCast is based on a generic Buildroot Linux image. Its mod framework was written entirely by me, but I couldn't have done it without the help of various individuals. Thanks, @cj_000, for helping me and putting up with my stupid questions in IRC. And thank you, @tvall, for releasing your update-free images so promptly up until now. Without those, FlashCast would have a much smaller potential user base.

    Where do I get it?

    Downloads and source code are available at FlashCast's GitHub repository. The latest version is currently v1.3.
    10
    How do I know if I have A Chromecast with a vulnerable bootloader ?

    The initial software which the Chromecast shipped with, build 12072, had a vulnerable bootloader. In all following software versions (12840, 12940, and 13300), the vulnerability is patched and FlashCast can't be used. If your Chromecast has been allowed to access the internet, it will have updated itself and will not be vulnerable. If you have not set up your Chromecast and it still has the software from the factory, it may or may not be vulnerable, depending on when you bought it. To check, you can plug it in (but not set it up), and check its "Build" in the Chromecast app. Alternatively, you can simply try to boot FlashCast on it. If it's patched, nothing bad will happen; the USB drive will simply fail to boot.
    5
    The problem is Windows' poor handling of flash drive partitions. @ddggttff3 figured out how to force Windows to reformat a FlashCast drive from the command line the other day. When he wakes up tomorrow, I'll see if I can get him to post instructions. Sorry for the inconvenience.

    Have a Tutorial Video:
    http://www.youtube.com/watch?v=NRsUuiuWQMM

    Not my best work, but was somewhat rushed. Hope that's OK.

    Commands Used in CMD:
    Code:
    diskpart
    list disk
    select disk * (where * is your jump drive disk number)
    clean
    convert mbr
    create partition primary

    Like I said in the video, make sure you select the drive letter of your jump drive! If you select the wrong disk you can accidentally wipe all of the data from your computer. Me, XDA, and team eureka are NOT responsible for any data loss.
    5
    I have just released FlashCast version 1.1. A changelog and downloads are available on GitHub here.
    5
    So by using this, OTA updates would no longer be pushed to the device and you wouldn't get new features/fixes, correct?

    If so, how does one keep root and still get the latest updates?

    This is just a flashing tool, so all of your questions depend on the ROM you flash. If you flash the 13300 package I made, it will disable updates and enable telnet/adb. If you want updates in the future, just wait for me,or someone else to release a new image once a new update rolls out.

    So does this mean it will be possible to get at the hard-coded Google DNS server in the Chromecast for those of us wanting better Netflix outside of the US?

    Yes, it means you can change the DNS server chromecast uses. I actually plan on making a flashable zip to do just that in the next few days.

    EDIT: Posted the flashable zip in its own thread. http://xdaforums.com/showthread.php?t=2455888