Insecure Temporary File Handling in Elio Allows Local File Overwrite

Executive Summary

Elio through version 1.13.0 has an insecure temporary file vulnerability. It creates temporary files with predictable names in the system's temp directory. Attackers can pre-create symbolic links at these paths. When Elio opens these files, it follows symlinks and truncates or overwrites files owned by other users. The attacker needs to know the victim's process ID and exploit a race condition to place the symlink before Elio creates the file.

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Detection Guidance

Check for predictable temporary file patterns in Elio's operations. Monitor /tmp for files named elio-{label}-{pid}-{counter}.tmp. Look for symlinks pointing to sensitive files created before Elio's process starts. Review system logs for unexpected file truncations or overwrites during preview operations.

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Impact Analysis

This vulnerability allows local attackers to overwrite files owned by other users on the system. If you use Elio to preview media, fonts, or archives, an attacker could replace important files with malicious content. This could lead to data loss, system instability, or unauthorized code execution. The attack requires local access and the ability to predict file paths.

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Compliance Impact

This vulnerability could potentially impact compliance with GDPR and HIPAA by enabling local attackers to overwrite files owned by other users. For GDPR, unauthorized file access or modification may violate data integrity and confidentiality principles. For HIPAA, file overwrites could compromise protected health information integrity if medical data files are targeted.

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Mitigation Strategies

Upgrade Elio to the latest version beyond 1.13.0 if available. Avoid using Elio for preview operations until patched. Restrict write access to /tmp. Monitor for suspicious symlink creation in temporary directories. Consider disabling preview features if not critical.

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