Full Report
The IoT OWASP top 10 includes Insecure Default Settings. To the author, this means a configuration that is insecure by default, a setting that the user must explicitly change, or a setting that is bad and unchangeable. They have several examples of this in the article. The first target is the Kobo eReader, an alternative to Amazon Kindles. Using a debug shell, the default credentials are admin:admin. So, with access to a device, it's possible to login to it. Additionally, there is no key signing so it's trivial to reflash the firmware with arbitrary code. The next thing they looked at was a Bitcoin ATM Kioisk. After clicking around for a while, they were able to access the Windows control panel. With access to the system logged in as an administrator, it would have been possible to backdoor the entire thing. To demonstrate this, they used Minikatz to extract creds and ran Doom on it. A good post on some real-world issues. Insecure defaults have existed for years and will likely continue to do so. Good finds!
Analysis Summary
# Vulnerability: Insecure Default Settings and Lack of Firmware Verification in Embedded Systems
## CVE Details
- **CVE ID:** N/A (General architectural flaws; no specific CVEs assigned to these findings)
- **CVSS Score:** Estimated 6.8 - 7.6 (Medium/High)
- **CWE:** CWE-1392 (Use of Default Credentials), CWE-284 (Improper Access Control), CWE-1263 (Improper Physical Access Control)
## Affected Systems
- **Products:**
1. Kobo eReader (specifically Clara Colour)
2. Bitcoin ATM Kiosk (unspecified manufacturer)
- **Versions:**
- Kobo Firmware v4.41.23145 and earlier
- **Configurations:**
- Devices with accessible UART/Debug ports.
- Windows-based kiosks with accessible UI escape sequences.
## Vulnerability Description
The research highlights two primary flaws categorised under the OWASP IoT Top 10 "Insecure Default Settings":
1. **Hardcoded Credentials:** The Kobo eReader shipped with a root-level account (admin:admin) accessible via physical UART debug pins.
2. **Lack of Secure Boot/Code Signing:** The Kobo firmware does not verify the integrity or authenticity of the software. This allows "re-flashing" with modified code, enabling persistent backdoors.
3. **Kiosk Breakout:** In the Bitcoin ATM case, improper lockdown of the Windows environment allowed physical interaction to trigger OS-level features (Control Panel), leading to full administrative takeover.
## Exploitation
- **Status:** PoC available (demonstrated by researchers)
- **Complexity:** Low (Credentials were guessable; breakout required only physical interaction)
- **Attack Vector:** Physical (Access to device internals or UI)
## Impact
- **Confidentiality:** High (Recovery of plaintext Wi-Fi keys, user data, and system credentials via Mimikatz)
- **Integrity:** High (Ability to reflash firmware or install backdoors)
- **Availability:** High (Ability to render devices inoperable or run unauthorized software like Doom)
## Remediation
### Patches
- **Kobo eReader:** Upgrade to **Firmware v4.42.23296** or later. This patch removes the `admin` account from `/etc/passwd`.
### Workarounds
- **Physical Security:** Enclose debug ports (UART) to prevent easy access to the PCB.
- **Kiosk Lockdown:** Implement "Kiosk Mode" strictly, disabling right-clicks, specialized hotkeys, and access to the file system or Windows Control Panel.
- **Service Minimization:** Disable unused services (Telnet/FTP) that may be running by default.
## Detection
- **Indicators of Compromise:**
- Presence of unknown entries in `/etc/passwd`.
- Unexpected modifications to `wpa_supplicant.conf`.
- Unexplained system reboots (indicating a firmware reflash).
- **Detection Methods:**
- Audit firmware checksums against known vendor hashes.
- Monitor for unauthorized hardware attached to UART/Serial interfaces.
## References
- **Vendor Advisory:** hxxps://www.softwaresecured[.]com/post/default-configurations-in-embedded-systems
- **CWE-1392:** hxxps://cwe.mitre[.]org/data/definitions/1392.html
- **Kobo Firmware Source:** hxxps://pgaskin[.]net/KoboStuff/kobofirmware.html