CVE-2022-31269 Overview
CVE-2022-31269 is a hardcoded credentials vulnerability affecting Nortek Linear eMerge E3-Series access control devices through firmware version 0.32-09c. The vulnerability stems from the device placing administrative credentials in a publicly accessible file (/test.txt), which can allow an attacker to gain unauthorized access to building access control systems and potentially open doors without authorization.
This vulnerability is particularly concerning because it affects physical security infrastructure. Even in environments where administrators have taken steps to change the default credentials addressed in CVE-2019-7271, this separate credential disclosure vulnerability exposes the new admin credentials, effectively negating any security improvements made by changing defaults.
Critical Impact
Attackers can retrieve admin credentials from a publicly accessible file, enabling unauthorized physical access to buildings by controlling door locks through the eMerge E3 access control system.
Affected Products
- Nortek Linear eMerge E3-Series Firmware through version 0.32-09c
- Nortek Linear eMerge E3 Hardware devices
- NortekControl eMerge E3 Access Control Systems
Discovery Timeline
- 2022-08-25 - CVE-2022-31269 published to NVD
- 2024-11-21 - Last updated in NVD database
Technical Details for CVE-2022-31269
Vulnerability Analysis
This vulnerability is classified as CWE-798 (Use of Hard-coded Credentials), though it manifests specifically as insecure storage of credentials. The eMerge E3-Series devices store administrator credentials in a plaintext file accessible via the web interface at /test.txt. This file persists even after administrators change the default credentials that were the subject of CVE-2019-7271.
The vulnerability allows unauthenticated remote attackers to retrieve valid administrative credentials simply by requesting this file from the device's web server. Once obtained, these credentials grant full administrative access to the access control system, including the ability to unlock doors, modify access schedules, and alter user permissions.
Root Cause
The root cause is a leftover debug or testing file (/test.txt) that was not removed from production firmware. This file contains the current administrative credentials in plaintext format, creating a direct path for credential theft. The file appears to have been used during development or testing but was inadvertently included in production firmware releases through version 0.32-09c.
This represents a fundamental secure development lifecycle failure where debugging artifacts were not properly identified and removed before release. The persistence of this file across multiple firmware versions suggests a lack of security code review processes.
Attack Vector
The attack is straightforward and requires no authentication or specialized tools. An attacker with network access to the eMerge E3 device can simply request the /test.txt file via HTTP. The attack flow involves network reconnaissance to identify eMerge E3 devices, which can be done through banner grabbing or Shodan searches. Once a device is identified, the attacker directly accesses the credential file at http://<device-ip>/test.txt. With the retrieved admin credentials, the attacker can then log into the administrative interface. From there, full control is obtained over the access control system, enabling the attacker to open doors, modify access permissions, or disable security features.
Given that these devices control physical building access, successful exploitation has direct real-world impact on physical security. The Packet Storm Security advisory provides additional technical details on this vulnerability.
Detection Methods for CVE-2022-31269
Indicators of Compromise
- HTTP GET requests to /test.txt on eMerge E3 devices from unauthorized IP addresses
- Unusual administrative login activity following external network access to the credential file
- Multiple failed or successful authentication attempts from IP addresses that previously accessed /test.txt
- Unexpected door unlock events or access schedule modifications
Detection Strategies
- Monitor web server access logs on eMerge E3 devices for requests to /test.txt
- Implement network intrusion detection rules to alert on HTTP requests containing /test.txt destined for access control systems
- Deploy honeypot files or modify web server configurations to generate alerts when the vulnerable endpoint is accessed
- Correlate network access logs with authentication events to identify credential harvesting followed by administrative access
Monitoring Recommendations
- Segment access control systems on isolated network segments with restricted access
- Implement logging and monitoring for all administrative access to eMerge E3 devices
- Deploy network monitoring solutions to track unusual traffic patterns to physical security infrastructure
- Review door unlock audit logs regularly for unauthorized access events
How to Mitigate CVE-2022-31269
Immediate Actions Required
- Restrict network access to eMerge E3 devices to authorized management stations only using firewall rules or VLANs
- Block external/internet access to these access control devices immediately
- Review access logs for any previous exploitation attempts
- Audit door access logs for any unauthorized unlock events
Patch Information
No official vendor patch information is available in the CVE data. Organizations should contact Nortek Control directly to inquire about firmware updates that address this vulnerability. Visit the Nortek Control Access Control page for product support information.
Until a patch is available, network-level mitigations are essential. Additional technical details about this vulnerability can be found in the GitHub Gist by Omar Hashem.
Workarounds
- Implement network segmentation to isolate access control systems from general network traffic
- Configure firewall rules to block access to /test.txt at the network perimeter or on a reverse proxy
- Place eMerge E3 devices behind a VPN to require authentication before any device access
- Consider implementing web application firewall rules to block requests to the vulnerable endpoint
# Example iptables rule to restrict access to eMerge E3 device
# Replace 192.168.1.100 with your eMerge E3 device IP
# Replace 10.0.0.0/24 with your authorized management network
iptables -A INPUT -d 192.168.1.100 -s 10.0.0.0/24 -p tcp --dport 80 -j ACCEPT
iptables -A INPUT -d 192.168.1.100 -s 10.0.0.0/24 -p tcp --dport 443 -j ACCEPT
iptables -A INPUT -d 192.168.1.100 -p tcp --dport 80 -j DROP
iptables -A INPUT -d 192.168.1.100 -p tcp --dport 443 -j DROP
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