Compliance Impact

This vulnerability creates a backdoor that allows unauthorized remote access with full root privileges, impacting the confidentiality, integrity, and availability of the affected system.

Such unauthorized access and potential data compromise could lead to violations of common standards and regulations like GDPR and HIPAA, which require protection of sensitive data and secure access controls.

Because the vulnerability enables attackers to bypass authentication and execute arbitrary commands, it undermines security controls necessary for compliance with these regulations.

No known mitigations or countermeasures have been published, increasing the risk of non-compliance if the affected device is used in environments subject to these standards.

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Executive Summary

This vulnerability exists in the EFM ipTIME A8004T router firmware version 14.18.2, specifically in the Debug Interface component's function httpcon_check_session_url within the file /sess-bin/d.cgi. It involves manipulation of the cmd argument to create a backdoor that allows unauthorized remote access. The vulnerability arises from improper session validation and authentication bypass, enabling attackers to reset the administrator password, enable a hidden remote support feature, and execute arbitrary shell commands with root privileges. Exploitation requires a high level of authentication complexity but can be performed remotely. The vulnerability is classified as CWE-912 (undocumented functionality) and corresponds to MITRE ATT&CK technique T1588.001. [1, 2]

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Impact Analysis

This vulnerability can severely impact you by allowing an attacker to gain unauthorized root access to your EFM ipTIME A8004T router remotely. The attacker can bypass authentication, reset the administrator password, enable remote support, and execute arbitrary commands on the device. This compromises the confidentiality, integrity, and availability of the system, potentially leading to full control over the router and any network it manages. [1, 2]

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Detection Guidance

Detection can focus on monitoring HTTP requests targeting the vulnerable router for suspicious access patterns. Specifically, look for HTTP requests to the path `/cgi/timepro.cgi` which bypass authentication, or requests to `/sess-bin/d.cgi` containing the `cmd` parameter with unusual or suspicious shell commands. Network intrusion detection systems (NIDS) can be configured to alert on these URL patterns and parameters. Additionally, checking for the presence of the hardcoded magic string `!@dnjsrurelqjrm*&` in requests to `/sess-bin/d.cgi` can indicate exploitation attempts. Commands such as using curl or wget to test these endpoints can be used, for example: `curl -v http://<router-ip>/cgi/timepro.cgi` or `curl -v 'http://<router-ip>/sess-bin/d.cgi?cmd=id'` to see if unauthorized command execution is possible. Monitoring router logs for unusual access or command execution attempts is also recommended. [2]

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Mitigation Strategies

Immediate mitigation steps include replacing the affected EFM ipTIME A8004T router firmware version 14.18.2 with an alternative device or firmware version that is not vulnerable, as no official patches or countermeasures have been published. Until replacement, restrict network access to the router's management interfaces, especially blocking external access to `/cgi/timepro.cgi` and `/sess-bin/d.cgi` endpoints. Disable or restrict the 'Remote Support' feature if enabled. Monitor network traffic for exploitation attempts and consider isolating the device from critical network segments. Since the vendor has not responded with a fix, proactive replacement is the most reliable mitigation. [1, 2]

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