CVE-2025-52574: SysmonElixir Path Traversal Vulnerability

CVE-2025-52574 Overview

SysmonElixir is a system monitor HTTP service built in Elixir. A path traversal vulnerability exists in versions prior to 1.0.1 that allows remote attackers to read arbitrary files from the server through the /read endpoint. The endpoint reads any file from the server, including sensitive system files like /etc/passwd by default, without proper input validation or access restrictions.

Critical Impact

Remote unauthenticated attackers can exploit this vulnerability to read sensitive files from the server, potentially exposing credentials, configuration data, and other confidential information that could be leveraged for further attacks.

Affected Products

• SysmonElixir (elixir-system-monitor) versions prior to 1.0.1

Discovery Timeline

• 2025-06-24 - CVE CVE-2025-52574 published to NVD
• 2025-06-26 - Last updated in NVD database

Technical Details for CVE-2025-52574

Vulnerability Analysis

This vulnerability is classified as CWE-22 (Improper Limitation of a Pathname to a Restricted Directory), commonly known as a path traversal or directory traversal vulnerability. The flaw exists in the /read endpoint of the SysmonElixir HTTP service, which processes file path requests without proper sanitization or access control restrictions.

Prior to the patch, the application accepted arbitrary file paths and would return the contents of any readable file on the system. This lack of input validation allowed attackers to use the endpoint to traverse outside the intended directory structure and access sensitive system files. The vulnerability is particularly dangerous because it requires no authentication and can be exploited remotely over the network with minimal complexity.

Root Cause

The root cause of this vulnerability is insufficient input validation on the /read endpoint. The application failed to implement a whitelist or proper path restrictions, allowing user-supplied input to directly control which files the server reads. Without sanitizing the requested file path or restricting access to a specific directory, attackers could specify paths to sensitive system files outside the intended scope.

Attack Vector

The attack vector is network-based, requiring no privileges or user interaction. An attacker can exploit this vulnerability by sending a crafted HTTP request to the /read endpoint with a path traversal sequence or direct path to sensitive files. The server would process the request and return the contents of the specified file.

For example, an attacker could request /etc/passwd to enumerate system users, /etc/shadow (if readable) to obtain password hashes, or application configuration files containing database credentials and API keys. The exploitation is straightforward and can be performed using standard HTTP tools like curl or web browsers.

Technical details and the security fix can be reviewed in the GitHub Security Advisory.

Detection Methods for CVE-2025-52574

Indicators of Compromise

• HTTP requests to the /read endpoint containing path traversal sequences such as ../ or direct paths to sensitive system files
• Access logs showing requests for /etc/passwd, /etc/shadow, or other system configuration files
• Unusual file read patterns from the SysmonElixir service process accessing files outside priv/data directory

Detection Strategies

• Monitor HTTP access logs for requests to the /read endpoint containing suspicious file paths or traversal patterns
• Implement web application firewall (WAF) rules to detect and block path traversal attempts targeting the /read endpoint
• Deploy network intrusion detection signatures for HTTP requests attempting to access /etc/passwd or similar sensitive files

Monitoring Recommendations

• Enable detailed access logging for the SysmonElixir service to capture all requests to the /read endpoint
• Set up alerts for any file access attempts outside the authorized priv/data directory
• Monitor for reconnaissance activity targeting the application to enumerate accessible files

How to Mitigate CVE-2025-52574

Immediate Actions Required

• Upgrade SysmonElixir to version 1.0.1 or later immediately
• If immediate patching is not possible, disable or restrict access to the /read endpoint at the network level
• Review server access logs for evidence of exploitation attempts
• Audit any systems running vulnerable versions to identify potential data exposure

Patch Information

The vulnerability has been patched in version 1.0.1 of SysmonElixir. The fix implements a whitelist that restricts file reading operations to only files under the priv/data directory, preventing access to arbitrary system files. The patch commit is available on GitHub.

Workarounds

• Deploy a reverse proxy or web application firewall in front of the service to filter requests containing path traversal sequences
• Use network segmentation to limit which systems can access the SysmonElixir service
• Implement firewall rules to restrict access to the /read endpoint to trusted IP addresses only
• Run the service with minimal filesystem permissions to limit the impact of potential exploitation

# Example: Restrict access to the service using iptables
# Allow only trusted networks to access the SysmonElixir port
iptables -A INPUT -p tcp --dport 4000 -s 10.0.0.0/8 -j ACCEPT
iptables -A INPUT -p tcp --dport 4000 -j DROP