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Samsung Firmware Magic

Samsung distributes firmware updates for their SSDs for either "Windows" or "Mac". Ironically, both of these are bootable Linux .iso files, containing the actual firmware and update program.

The .iso files can be unpacked, but ultimately we end up with an obfuscated binary blob, even for the meta information.

For the upstream file downloads, see

https://www.samsung.com/semiconductor/minisite/ssd/download/tools/

Out of curiosity, I decided to create a decryption tool for this obfuscated format, which is found in this repository.

Unpacking iso image to firmware blob

First, we download a firmware iso:

`wget http://downloadcenter.samsung.com/content/FM/201711/20171102105105735/Samsung_SSD_850_PRO_EXM04B6Q_Win.iso`

Next, we unpack the relevant file from the iso, the initrd:

`7z x Samsung_SSD_850_PRO_EXM04B6Q_Win.iso initrd`

This file is a gzip-compressed cpio archive, so use 7z to strip gzip:

`7z x initrd`

This produces initrd~, containing the uncompressed contents. From here we extract the directory of interest, root/fumagician:

`7z -ofw x 'initrd~' root/fumagician`

This creates fw/root/fumagician in the current directory:

$ cd fw/root/fumagician
$ ls -l
total 5408
-rw-rw-r-- 1 user user    2124 1971-03-22 19:52 DSRD.enc
-rw-rw-r-- 1 user user 4752867 1971-03-22 19:52 EXM04B6Q.enc
-rw-rw-r-- 1 user user  772516 2016-10-14 10:42 fumagician
-rw-rw-r-- 1 user user     290 2016-10-14 10:42 fumagician.sh

The files DSRD.enc (xml list of firmwares) and EXM04B6Q.enc (firmwares) are the obfuscated files, that we can now decrypt.

Decrypting firmware blob

The included decode.py script will unpack these .enc files, like so:

## show xml on stdout:
$ ./samsung-magic.py < fw/root/fumagician/DSRD.enc

## decrypt firmware to file:
$ ./samsung-magic.py < fw/root/fumagician/EXM04B6Q.enc > EXM04B6Q.bin

Seemingly, the folks at Samsung are huge fans of nesting things, because the decrypted EXM04B6Q.bin file is actually a zip file, containing encrypted firmware files:

$ unzip -l EXM04B6Q.bin
Archive:  EXM04B6Q.bin
  Length      Date    Time    Name
---------  ---------- -----   ----
  1048576  2017-02-19 10:41   EXM04B6Q_10170217.enc
  1048576  2017-02-19 10:41   EXM04B6Q_20170203.enc
  1048576  2017-02-19 10:41   EXM04B6Q_30170203.enc
  1048576  2017-02-19 10:41   EXM04B6Q_40170902.enc
  1048576  2017-02-19 10:41   EXM04B6Q_50170208.enc
  1048576  2017-02-19 10:41   EXM04B6Q_60170208.enc
---------                     -------
  6291456                     6 files

Luckily, the encryption is exactly the same, so samsung-magic.py can decrypt these as well:

$ unzip EXM04B6Q.bin
$ ./samsung-magic.py < EXM04B6Q_10170217.enc > EXM04B6Q_10170217.bin

Now, at last, we have the raw firmware.

Enjoy!


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