CVE-2024-50355: LibreNMS has a Persistent XSS from Insecure Input Sanitization Affects Multiple Endpoints

Summary

The application fail to sanitising inputs properly and rendering the code from user input to browser which allow an attacker to execute malicious javascript code.

Details

User with Admin role can edit the Display Name of a device, the application did not properly sanitize the user input in the device Display Name, if java script code is inside the name of the device Display Name, its can be trigger from different sources.

PoC

1. Use an Admin role user to change the Display Name of a device into the payload <img src="x" onerror="alert(document.cookie)">

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2.1. Go to manage user and choose Manage Access

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2.2. A pop-up will show

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3.1. Create a new Alert Rule where it will check if the device is up or down by using ICMP and then add the rule to the device.

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3.2. Once the device is down, there will be an alert in the Alerts Notifications

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3.3. Hover over the Hostname will see a pop-up.

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4.1. The same can be trigger in the Alert History once hover over the Device field.

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5.1. The same can be trigger once hover over the Hostname field from the Event Log of the device.

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6.1. The same can be trigger in the Outages function in the Logs of the device.

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7.1. In the Active Alerts of the device.

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8.2. In the Alert History of the device.

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9.1. They can also be trigger in the dashboard.

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10.1. Also if change the payload into <img src="x" onerror="alert(document['cookie'])">, it can also be trigger in the Availability Map.

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Impact

It could allow authenticated users to execute arbitrary JavaScript code in the context of other users' sessions. Impacted users could have their accounts compromised, enabling the attacker to perform unauthorized actions on their behalf.