Executive Summary

This vulnerability exists in the V-SOL GPON/EPON OLT Platform version 2.03, where a normal authenticated user can escalate their privileges to administrative level by sending a crafted HTTP POST request to the user management endpoint. Specifically, by setting the 'user_role_mod' parameter to the integer value '1' in the request, the system improperly grants admin rights without proper authorization checks. [2, 3]

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Impact Analysis

An attacker who exploits this vulnerability can gain administrative access to the V-SOL GPON/EPON OLT device remotely. This allows them to control the device, potentially altering configurations, disrupting services, or accessing sensitive network information. Since the device is used in broadband access technology for FTTH deployments and supports critical applications like VPN, IP cameras, and enterprise LANs, the impact can be significant, including network compromise and service disruption. [2, 3]

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Detection Guidance

This vulnerability can be detected by monitoring HTTP POST requests to the user management endpoint (e.g., http://<device-ip>/action/user.html) and checking for the parameter 'user_role_mod' set to the integer value '1'. A practical detection method is to capture and analyze HTTP traffic to identify such crafted POST requests. For example, using curl to test the vulnerability: curl -X POST -d 'user_role_mod=1&other_params=...' http://<device-ip>/action/user.html. Additionally, network monitoring tools or intrusion detection systems can be configured to alert on POST requests containing 'user_role_mod=1'. [2, 3]

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Mitigation Strategies

Immediate mitigation steps include restricting access to the device's web management interface to trusted users only, implementing network-level access controls such as firewall rules to limit HTTP POST requests to the user management endpoint, and monitoring for suspicious POST requests with 'user_role_mod=1'. If possible, apply any available patches or updates from the vendor to fix the privilege escalation vulnerability. Additionally, educating users to avoid visiting untrusted websites while logged into the device can reduce risk from malicious crafted requests. [2, 3]

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