CVE-2016-10709 in pfSense
Summary
by MITRE
pfSense before 2.3 allows remote authenticated users to execute arbitrary OS commands via a '|' character in the status_rrd_graph_img.php graph parameter, related to _rrd_graph_img.php.
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Analysis
by VulDB Data Team • 02/01/2021
The vulnerability CVE-2016-10709 affects pfSense versions prior to 2.3, representing a critical command injection flaw that enables authenticated remote attackers to execute arbitrary operating system commands. This vulnerability resides within the status_rrd_graph_img.php script and is specifically triggered by the presence of a pipe character '|' in the graph parameter, which is processed through the underlying _rrd_graph_img.php component. The flaw demonstrates characteristics consistent with CWE-77 Command Injection, where user-supplied input is directly incorporated into system command execution without proper sanitization or validation.
The technical implementation of this vulnerability exploits the insufficient input validation mechanisms within pfSense's web interface, particularly in how it handles RRD (Round Robin Database) graph generation requests. When an authenticated user submits a malicious graph parameter containing the pipe character, the system fails to properly escape or filter the input before passing it to underlying shell commands. This oversight creates an environment where attackers can chain commands by leveraging the pipe operator to execute additional system commands beyond the intended graph generation functionality. The vulnerability specifically targets the web-based management interface of pfSense, which typically runs on standard web servers and processes user requests through PHP scripts that interact with system-level operations.
Operationally, this vulnerability presents a severe risk to network infrastructure security as it allows attackers who have gained authentication credentials to escalate their privileges from mere user access to full system command execution. The impact extends beyond simple command injection, as successful exploitation can enable attackers to modify system configurations, access sensitive data, install backdoors, or even compromise the entire network appliance. Given that pfSense is widely deployed as a firewall and router management platform, this vulnerability could affect thousands of network environments, potentially providing attackers with persistent access to critical network infrastructure. The authenticated nature of the vulnerability means that attackers must first obtain valid credentials, but this requirement does not significantly reduce the overall risk given the potential for credential compromise through various attack vectors including phishing, brute force attempts, or exploitation of other vulnerabilities.
Mitigation strategies for CVE-2016-10709 should prioritize immediate patching of pfSense installations to version 2.3 or later, where the vulnerability has been addressed through proper input sanitization and validation mechanisms. Network administrators should also implement additional security controls including web application firewalls to monitor and filter suspicious input patterns, particularly those containing shell metacharacters like pipe characters. The remediation process should include comprehensive security auditing of all pfSense installations, credential rotation for affected systems, and implementation of principle of least privilege access controls. Organizations should also consider implementing network segmentation and monitoring to detect anomalous command execution patterns that might indicate exploitation attempts. This vulnerability aligns with ATT&CK technique T1059.001 Command and Scripting Interpreter: PowerShell where attackers can leverage system command execution capabilities to achieve their objectives, making it essential for security teams to monitor for such activities within their network infrastructure.