Amazon Kindle Bug May Allow Hackers to Take Over Your Account

 Amazon recently patched three vulnerabilities in the Kindle e-reader platform that would have allowed a bad actor to compromise the device, take over and even steal your money.

How it Works

The exploit was discovered by researcher Yogev Bar-On from Readlmode Labs in a report they published on Thursday. The vulnerability was nicknamed “KindleDrip'' and uses a feature called “SendtoKindle” that cybercriminals could use to send a malicious e-book through email, which, when added to the Kindle e-reader, would install malware and take over in a three-pronged attack.

The attackers would need to know the user’s email address, the one attached to the device, but with that, they could essentially add the malicious ebook automatically, and the code installed would run as root, exposing them to a whole host of dangers.

The way this works is a three-step process using the three exploitable vulnerabilities. First, the hacker sends the malicious e-book. The second flaw then allows the e-book to be loaded into the user’s Kindle library and malware to be installed. The third issue then elevates the user’s privileges, so the code runs as “root.”

The real danger of this one is that once hacked, the threat actor could completely take over the person’s account, access their credit card number, and make purchases.

The Larger Issue

The way the SendtoKindle feature is supposed to work is that the email signature is authenticated, so no e-books can be sent or accepted without being a valid attachment to the email from the “Approved Personal Document E-mail List.”

However, as Bar-On discovered, this was not the case. He tested his theory and found that not only was the email sender not verified but that he was able to accomplish the hack using a “spoofed” email address. The book then automatically showed up in the library without even having received an email at all.

In theory, the attacker would have to know the person’s email address tied to the Kindle. On-Bar said this was easy to circumvent using a brute-force attack.

According to The Hacker News, “However, once the e-book is sent to a victim device, the attack moves to the next stage. It exploits a buffer overflow flaw in the JPEG XR image format library as well as a privilege escalation bug in one of the root processes (“stackdump”) to inject arbitrary commands and run the code as root.

Thus when an unsuspecting user opens the e-book and taps on one of the links in the table of contents, the Kindle would open an HTML page in the browser that contained a specially-crafted JPEG XR image and parse the image file to run the attack code — thereby allowing the adversary to steal the user’s credentials, take control over the device, and virtually access personal information associated with the victim.”

How Amazon Responded

Amazon fixed all three issues on December 10, 2020. The patch addresses issues with Kindle e-readers manufacturers after 2014. Researchers, Bar-On’s reported the issue on October 17, and he was awarded $18,000 by Amazon as part of the Amazon Vulnerability Research Program.

As part of the remediation, Amazon now sends a verification link to anyone who receives an e-book from an unrecognized email address.

The Hacker News provides assistance in upgrading to the fixed version “Software updates on Kindle devices are by default downloaded and installed when connected wirelessly. Users can head to Settings → Menu → Device Info to check if their firmware is up-to-date, and if not, manually download and install the 5.13.4 update to mitigate the flaws.”