Amazon FireOS 5.3.6.3 Man-In-The-Middle

`[Original blog post here:  
https://wwws.nightwatchcybersecurity.com/2019/02/07/content-injection-in-amazon-kindles-fireos-cve-2019-7399/]  
  
SUMMARY  
  
The FireOS operating system provided by Amazon for Fire tablet devices  
can be injected with malicious content by an MITM attacker. An  
attacker can also capture the serial number of the device. The root  
cause is lack of HTTPS for legal content (terms of use and privacy  
policy) within the settings section.  
  
The issue was discovered in FireOS v5.3.6.3 and fixed by the vendor in  
v5.3.6.4 that was released in November 2018. Devices will  
automatically update to the latest version. CVE-2019-7399 has been  
assigned by MITRE to track this issue.  
  
VULNERABILITY DETAILS  
  
FireOS is an operating system provided by Amazon for the Fire tablet  
devices. It is a customized fork of Android. While monitoring network  
traffic on a test device, we observed that several calls from the  
settings section (terms of use and privacy policy) are done without  
HTTPS and can be injected with malicious content by an MITM attacker.  
It is also possible for the attacker to observe this traffic and  
capture the serial number (DSN) of the device.  
  
Steps To Replicate (on Ubuntu 18.04)  
1. Install the application on the Android device but do not start it.  
2. Install dnsmasq and NGINX on the Linux host:  
sudo apt-get install dnsmasq nginx  
  
3. Modify the /etc/hosts file to add the following entry to map the  
domain name to the Linux host:  
192.168.1.x www.kindle.com  
192.168.1.x kindle.com  
  
4. Configure /etc/dnsmasq.conf file to listen on the IP and restart DNSMASQ  
listen-address=192.168.1.x  
sudo /etc/init.d/dnsmasq restart  
  
5. Add a file with malicious content (you may need to use sudo):  
cd /var/www/html  
mkdir support  
echo powned >support/privacy  
echo powned >support/terms  
  
6. Modify the settings on the Kindle device to static, set DNS to  
point to a192.168.1.xa. AT THIS POINT a the Kindle device will resolve  
DNS against the Linux computer and serve the large servers file  
  
7. Tap aSettingsa, aLegal and Compliancea, and tap either aTerms of  
Usea or aPrivacya. Observe injected content.  
  
VENDOR RESPONSE AND MITIGATION  
  
The issue was discovered in FireOS v5.3.6.3 and fixed by the vendor in  
v5.3.6.4 that was released in November 2018. Devices will  
automatically update to the latest version. MITRE assigned  
CVE-2019-7399 to track this issue.  
  
REFERENCES  
  
Amazon tracking # PO135449968  
CVE-ID: CVE-2019-7399  
  
CREDITS  
  
Text of the advisory written by Yakov Shafranovich.  
  
TIMELINE  
  
2018-09-03: Initial report to the vendor  
2018-09-04: Report triaged and being reviewed by the vendor  
2018-09-17: Communication from the vendor, issue still being reviewed  
2019-01-10: Fix confirmed, communication regarding disclosure  
2019-01-30: Vendor pinged about CVE assignment  
2019-02-03: Draft advisory sent for review  
2019-02-04: CVE issued by MITRE  
2019-02-07: Public disclosure; minor syntax updates  
  
  
`