CVE-2020-13851 Overview
CVE-2020-13851 is a command injection vulnerability affecting Artica Pandora FMS version 7.44. The vulnerability allows authenticated remote attackers to execute arbitrary operating system commands through the events feature of the application. This flaw stems from improper input validation (CWE-78: OS Command Injection) where user-supplied input is passed to system commands without adequate sanitization.
Critical Impact
Authenticated attackers can achieve remote command execution on the underlying server, potentially leading to complete system compromise, data exfiltration, and lateral movement within the network.
Affected Products
- Pandora FMS 7.44
- Pandora FMS 7.0 NG 7XX series
Discovery Timeline
- 2020-06-11 - CVE-2020-13851 published to NVD
- 2024-11-21 - Last updated in NVD database
Technical Details for CVE-2020-13851
Vulnerability Analysis
This vulnerability allows remote command execution through the events feature in Pandora FMS. The root cause is insufficient input validation when processing user-controlled data that gets passed to operating system command execution functions. An attacker with valid credentials can craft malicious input that escapes the intended command context, allowing arbitrary command execution with the privileges of the web application process.
The attack requires network access and low-privilege authentication to the Pandora FMS console. Once authenticated, an attacker can leverage the events functionality to inject shell metacharacters or additional commands that will be executed on the underlying operating system.
Root Cause
The vulnerability is classified as CWE-78 (Improper Neutralization of Special Elements used in an OS Command). The events feature fails to properly sanitize user input before incorporating it into system command execution. Special shell characters and command separators are not adequately filtered, allowing attackers to break out of the intended command structure and execute arbitrary commands.
Attack Vector
The attack is network-based and requires authenticated access to the Pandora FMS web interface. An attacker must first obtain valid credentials (through credential theft, default credentials, or other means) and then navigate to the events feature. By injecting shell metacharacters such as semicolons, pipes, or backticks into vulnerable input fields, the attacker can append or substitute their own commands.
The exploitation does not require user interaction beyond the attacker's own actions, and the scope remains unchanged (the vulnerable component and impacted component are the same). Successful exploitation results in high impact to confidentiality, integrity, and availability of the affected system.
For detailed technical analysis and proof-of-concept information, see the Packet Storm Remote Command Exploit and the Core Security Pandora FMS Vulnerability Advisory.
Detection Methods for CVE-2020-13851
Indicators of Compromise
- Unusual process spawning from the web server process (e.g., www-data spawning /bin/sh, bash, or other shells)
- Unexpected network connections originating from the Pandora FMS server
- Anomalous entries in web application logs showing shell metacharacters in event-related requests
- New or modified files in web-accessible directories or system locations
Detection Strategies
- Monitor web application logs for requests to events-related endpoints containing shell metacharacters (;, |, &, backticks, $())
- Implement web application firewall (WAF) rules to detect and block OS command injection patterns
- Deploy endpoint detection to identify suspicious process chains where the web server spawns unexpected child processes
- Analyze network traffic for reverse shell patterns or unexpected outbound connections from the Pandora FMS server
Monitoring Recommendations
- Enable verbose logging for the Pandora FMS application and web server
- Configure SIEM alerts for command injection attack patterns in HTTP request parameters
- Implement file integrity monitoring on critical system directories and Pandora FMS installation paths
- Monitor for privilege escalation attempts following initial web application compromise
How to Mitigate CVE-2020-13851
Immediate Actions Required
- Upgrade Pandora FMS to a patched version that addresses CVE-2020-13851
- Restrict network access to the Pandora FMS console to trusted IP addresses only
- Review and audit user accounts with access to the events feature, removing unnecessary privileges
- Implement network segmentation to limit the blast radius of potential compromise
Patch Information
Organizations should consult the Core Security Advisories page and the official Pandora FMS vendor channels for updated software versions that remediate this vulnerability. Ensure all Pandora FMS installations are updated beyond version 7.44 to a release that contains the security fix.
Workarounds
- Implement a web application firewall (WAF) with rules to block command injection patterns targeting the events feature
- Restrict access to the Pandora FMS administrative interface using network-level controls (VPN, IP whitelisting)
- Disable or restrict access to the events feature if not operationally required
- Run the Pandora FMS web application with minimal operating system privileges to limit the impact of successful exploitation
# Example: Restrict access to Pandora FMS using iptables
# Allow access only from trusted management network
iptables -A INPUT -p tcp --dport 80 -s 10.0.0.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -s 10.0.0.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.


