Security researchers at Prizm Labs discovered a critical zero-click remote code execution (RCE) vulnerability in the SuperNote Nomad e-ink tablet. Exploiting a flaw in the device's update mechanism, an attacker could remotely execute arbitrary code with root privileges by sending a specially crafted OTA update notification via a malicious Wi-Fi access point. The attack requires no user interaction, making it particularly dangerous. The vulnerability stemmed from insufficient validation of update packages, allowing malicious firmware to be installed. Prizm Labs responsibly disclosed the vulnerability to SuperNote, who promptly released a patch. This vulnerability highlights the importance of robust security measures even in seemingly simple devices like e-readers.
This blog post by Prizm Labs details the discovery and exploitation of a zero-click remote code execution (RCE) vulnerability in the SuperNote A5X and A6X e-ink tablets, specifically those running firmware version 3.4.0.33. A zero-click exploit allows an attacker to compromise a device without requiring any interaction from the user. The vulnerability stemmed from the insecure implementation of the OTA (Over-The-Air) update mechanism.
The researchers began their investigation by analyzing the network traffic during an OTA update. They observed that the update process involved downloading a signed firmware image via HTTPS. While the use of HTTPS provided encryption, it did not protect against malicious manipulation if the attacker could compromise the update server or perform a man-in-the-middle attack. Crucially, the researchers found that the device did not validate the signature of the downloaded update package before writing it to the internal flash memory. This oversight allowed them to craft a malicious firmware update package containing arbitrary code.
The exploit process involved several steps. First, a malicious update package was constructed. This package contained a modified boot image, effectively replacing the legitimate SuperNote operating system with a malicious one. The malicious boot image included a modified init script designed to establish a reverse shell back to the attacker's machine, granting them full control over the device.
To deliver the malicious update, the researchers leveraged a classic man-in-the-middle attack technique, using ARP spoofing. ARP spoofing allows an attacker to intercept traffic intended for another device on the local network by impersonating its MAC address. By poisoning the ARP cache of the SuperNote device, the researchers redirected the device's OTA update request to their own malicious server, hosting the crafted update package.
When the SuperNote attempted to update, it downloaded the malicious package from the attacker's server. Due to the lack of pre-installation signature verification, the device accepted and applied the malicious update. Upon reboot, the modified init script within the malicious boot image executed, establishing the reverse shell and granting the attacker complete control. This access allowed them to execute arbitrary commands, exfiltrate sensitive data, and essentially take full ownership of the device.
The researchers highlighted the severity of this vulnerability, as it permitted silent and remote compromise of the targeted device. They responsibly disclosed the vulnerability to Ratta Supernote, the manufacturer of the device, who subsequently released a patched firmware version addressing the issue. The post concludes by emphasizing the importance of secure OTA update implementations and the need for robust security measures in internet-connected devices.
Summary of Comments ( 8 )
https://news.ycombinator.com/item?id=43615805
Hacker News commenters generally praised the research and write-up for its clarity and depth. Several expressed concern about the Supernote's security posture, especially given its marketing towards privacy-conscious users. Some questioned the practicality of the exploit given its reliance on connecting to a malicious Wi-Fi network, but others pointed out the potential for rogue access points or compromised legitimate networks. A few users discussed the inherent difficulties in securing embedded devices and the trade-offs between functionality and security. The exploit's dependence on a user-initiated firmware update process was also highlighted, suggesting a slightly reduced risk compared to a fully automatic exploit. Some commenters shared their experiences with Supernote's customer support and device management, while others debated the overall significance of the vulnerability in the context of real-world threats.
The Hacker News post discussing the 0-click RCE vulnerability in the SuperNote Nomad E-Ink tablet has generated a number of comments exploring various aspects of the vulnerability, its implications, and the SuperNote device itself.
Several commenters focus on the trade-offs between security and desired functionality, particularly regarding the device's cloud syncing feature. Some argue that the always-on nature of the sync feature, necessary for its intended seamless functionality, inherently increases the risk profile. The decision by SuperNote to leave Wi-Fi always enabled, even when the device is powered off, is highlighted as a key contributing factor to the vulnerability. The discussion touches upon the inherent difficulty of securing devices that require constant network connectivity.
The technical details of the vulnerability also receive attention. Commenters discuss the specifics of the exploit, including the use of maliciously crafted emails and the exploitation of a stack overflow vulnerability in the device's email client. The discussion highlights the importance of robust input sanitization and secure coding practices to prevent such vulnerabilities. Some commenters question the choice of technology used for the email client, suggesting that a simpler, less feature-rich implementation might have been more secure.
A recurring theme in the comments is the security of e-ink devices in general. Several users express concerns about the potential for similar vulnerabilities in other e-ink devices and the broader implications for the security of internet-connected devices in general. The relatively closed nature of the SuperNote ecosystem is also brought up, with some commenters suggesting that this may have contributed to the vulnerability going unnoticed for a longer period.
Several commenters praise the researchers for their responsible disclosure and the detailed write-up of the vulnerability. They acknowledge the importance of such research in improving the security of these devices.
Some comments delve into the practical implications of the vulnerability, discussing the potential for data theft and other malicious activities. The potential impact on users' privacy is a particular concern, given the sensitive nature of information often stored on such devices.
Finally, a few comments discuss the response from SuperNote, noting the company's acknowledgement of the vulnerability and their commitment to releasing a patch. There's some discussion about the timeliness of the response and the broader implications for the trust and reputation of the SuperNote brand.