GHSA-pr3g-phhr-h8fh

Summary

A vulnerability has been identified that allows an authenticated administrator to execute arbitrary code on the host server. By modifying the binary path settings for built-in network tools and bypassing an input filter, an attacker with administrative privileges can download and execute malicious payloads.

Details

The application allows administrative users to configure the absolute binary paths for network diagnostic tools at /settings/external/binaries. This setting does not sufficiently validate ensuring the paths remain restricted to safe, intended executables. These tools are invoked by sending a request to the GET /ajax/netcmd endpoint. While there is an existing input filter designed to restrict arguments to valid IP addresses or hostnames, this filter can be bypassed.

PoC

To reproduce this vulnerability, a remote HTTP server should be hosted with a malicious script/executable, ensure the remote server is reachable by the server running LibreNMS. The PoC will use the file malicious.sh containing the following content. It will return the content of /etc/passwd and /etc/group, current working directory, username that is running the script, and it will list files of the current directory.

#!/usr/bin/env bash

cat /etc/passwd
cat /etc/group
whoami
pwd
ls

1. Host a remote HTTP server that the server can reach and place the malicious script on the remote server. For demonstration, I will start it on localhost.

   <img width="593" height="481" alt="image" src="https://github.com/user-attachments/assets/ef235f8e-089b-462c-b12c-7b5ae2037fc5" />

2. Make sure the malicious script malicious.sh can be downloaded.

   <img width="516" height="100" alt="image" src="https://github.com/user-attachments/assets/60b04755-e824-4384-81f2-2feacdc8e273" />

3. Login with an admin account and navigate to Global Settings -> External -> Binary Locations <img width="797" height="201" alt="image"...