Subsequently, an attacker might have exploited a persistent cross-site scripting (XSS) vulnerability and the device's unencrypted cookie-named credentials, which store the Base64-encoded credentials of the active web session, to obtain administrator access and ultimately root it. By combining the discovered vulnerabilities and, for example, waiting for an admin user to log in to the device, an unauthenticated attacker can obtain root access to the Cosy+.

The firmware update file could then be decrypted, persistence could be established, and firmware-specific encryption keys could be accessed by expanding the attack chain. Furthermore, the secrets may be retrieved by using a hard-coded key that is kept in the binary for password encryption. Mutual TLS (mTLS) authentication secures the HTTPS connection between the Cosy+ and the Talk2m API. When a Cosy+ device is linked to a Talk2m account, it creates and submits a certificate signing request (CSR) to the Talk2m API that includes its serial number as the common name (CN).

This certificate is used for OpenVPN authentication and is accessible by the device using the Talk2m API. Nevertheless, researchers discovered that a threat actor might successfully launch a VPN session by enrolling their own CSR with a target device's serial number if they only relied on the device's serial number. The original device will no longer be accessible as the initial VPN session will be overwritten. Talk2m users will be routed to the attacker if they connect to the device with the VPN client program Ecatcher.

This allows attackers to launch additional attacks against the target client, such as gaining access to the victim client's RDP or SMB network services. This attack is made easier by the fact that the tunnel connection is unrestricted. Since the attacker receives the network traffic, it is possible to mimic the original network and systems to intercept user input from the victim, including uploaded PLC programs or other similar files.

Impact

• Privilege Escalation
• Exposure of Sensitive Data
• Cross-Site Scripting

Indicators of Compromise

CVE

• CVE-2024-33892
• CVE-2024-33893
• CVE-2024-33894
• CVE-2024-33895
• CVE-2024-33896
• CVE-2024-33897

Remediation

• Refer to HMS Security Advisory for patch, upgrade, or suggested workaround information.
• Organizations must test their assets for the vulnerability mentioned above and apply the available security patch or mitigation steps as soon as possible.
• Implement multi-factor authentication to add an extra layer of security to login processes.
• Regularly monitor network activity for any unusual behavior, as this may indicate that a cyberattack is underway.
• Organizations must stay vigilant and follow best practices for cybersecurity to protect their systems and data from potential threats. This includes regularly updating software and implementing strong access controls and monitoring tools.
• Develop a comprehensive incident response plan to respond effectively in case of a security breach or data leakage.
• Maintain regular backups of critical data and systems to ensure data recovery in case of a security incident.
• Adhere to security best practices, including the principle of least privilege, and ensure that users and applications have only the necessary permissions.
• Establish a robust patch management process to ensure that security patches are evaluated, tested, and applied promptly.
• Conduct security audits and assessments to evaluate the overall security posture of your systems and networks.
• Implement network segmentation to contain and isolate potential threats to limit their impact on critical systems.