Symlink Following in NousResearch Hermes-Agent

Executive Summary

This vulnerability is a security flaw found in the NousResearch hermes-agent version 0.8.0, specifically in the _check_sensitive_path function within the tools/file_tools.py file.

The flaw allows for symlink following manipulation, which means an attacker with local access can exploit symbolic link behavior to potentially perform unauthorized actions.

The exploit code for this vulnerability has been publicly released, increasing the risk of attacks.

Upgrading to version 0.9.0 of the hermes-agent mitigates this issue.

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Detection Guidance

This vulnerability involves a symlink bypass in the hermes-agent software on macOS, allowing unauthorized writes to sensitive system files like /etc/hosts by exploiting path resolution issues.

To detect if your system is vulnerable, you can check the version of hermes-agent installed. Versions prior to 0.9.0 are affected.

You can also attempt to verify if the _check_sensitive_path function properly blocks writes to sensitive paths by testing write attempts to files such as /etc/hosts or /private/etc/hosts using hermes-agent's write_file or patch tools.

Suggested commands to check the installed version and presence of the vulnerable code include:

• Check hermes-agent version: `hermes-agent --version` or check installed package version via your package manager.
• Search for the vulnerable function in the installed code: `grep -r '_check_sensitive_path' /path/to/hermes-agent/`.
• Attempt a controlled write test to a sensitive path (only if you have local access and permissions), for example using hermes-agent's API or CLI to write to /etc/hosts and observe if it is blocked.

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Impact Analysis

This vulnerability requires local access to be exploited, meaning an attacker must have some level of access to the affected system.

Successful exploitation can lead to integrity and availability impacts, as indicated by the CVSS scores, potentially allowing an attacker to manipulate files or disrupt service.

While confidentiality is not affected, the integrity and availability of the system or data could be compromised.

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Compliance Impact

The vulnerability allows unauthorized writes to sensitive system files on macOS due to a symlink bypass in path checking. This could potentially enable privilege escalation or unauthorized modification of system configuration files if the agent runs with sufficient permissions.

Such unauthorized access or modification of system files could lead to violations of security requirements in common standards and regulations like GDPR or HIPAA, which mandate protection of system integrity and prevention of unauthorized access to sensitive data or system components.

However, the provided information does not explicitly discuss or analyze the direct impact of this vulnerability on compliance with these standards.

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Mitigation Strategies

The recommended immediate step to mitigate this vulnerability is to upgrade the affected component, NousResearch hermes-agent, from version 0.8.0 to version 0.9.0.

This upgrade includes a patch identified as 311dac197145e19e07df68feba2cd55d896a3cd1 that fixes the security flaw in the _check_sensitive_path function.

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