CVE-2016-9684 in Secure Remote Access Server
Summary
by MITRE
The SonicWall Secure Remote Access server (version 8.1.0.2-14sv) is vulnerable to a Remote Command Injection vulnerability in its web administrative interface. This vulnerability occurs in the 'viewcert' CGI (/cgi-bin/viewcert) component responsible for processing SSL certificate information. The CGI application doesn't properly escape the information it's passed in the 'CERT' variable before a call to system() is performed - allowing for remote command injection. Exploitation of this vulnerability yields shell access to the remote machine under the nobody user account.
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Analysis
by VulDB Data Team • 07/31/2024
The SonicWall Secure Remote Access server vulnerability CVE-2016-9684 represents a critical remote command injection flaw that demonstrates the dangers of improper input validation in web applications. This vulnerability exists within the administrative web interface of SonicWall's secure remote access solution, specifically targeting version 8.1.0.2-14sv where the viewcert CGI component fails to properly sanitize user-supplied data. The flaw operates at the intersection of web application security and system-level execution, creating a pathway for attackers to escalate privileges and gain unauthorized access to network infrastructure. The vulnerability is classified under CWE-77 as "Improper Neutralization of Special Elements used in a Command ('Command Injection')", which directly aligns with the ATT&CK technique T1059.001 for Command and Scripting Interpreter, highlighting how this weakness can be leveraged for remote code execution.
The technical implementation of this vulnerability occurs within the /cgi-bin/viewcert CGI script that processes SSL certificate information for display purposes. When the application receives user input through the CERT variable parameter, it fails to properly escape or validate the data before passing it to the system() function call. This improper input handling creates a direct injection point where malicious commands can be embedded within the CERT parameter and executed with the privileges of the web server process. The vulnerability is particularly concerning because it operates at the system level, allowing attackers to execute arbitrary commands on the target machine with the permissions of the nobody user account, which typically represents the lowest privilege level available to web services.
The operational impact of this vulnerability extends far beyond simple remote code execution, as it provides attackers with a foothold for further network exploitation and lateral movement. The fact that the attack executes under the nobody user account, while limiting immediate privilege escalation, still allows for reconnaissance activities, data exfiltration, and potential exploitation of other vulnerabilities within the system. Security professionals should recognize this as a critical threat vector that could be exploited to compromise entire network infrastructures, particularly in environments where SonicWall appliances serve as primary security gateways. The vulnerability's remote nature means that attackers can exploit it without requiring physical access or local network presence, making it an attractive target for automated scanning and exploitation campaigns.
Organizations should implement immediate mitigations including patching the affected SonicWall appliances to the latest firmware versions that address this command injection vulnerability. Network segmentation and access controls should be strengthened to limit exposure of administrative interfaces to trusted networks only. Regular monitoring of web application logs for suspicious activity in the viewcert CGI component can help detect exploitation attempts. Additionally, implementing web application firewalls and input validation controls can provide additional layers of defense against similar vulnerabilities. The ATT&CK framework suggests that this vulnerability could be used as part of a broader attack chain, potentially leading to privilege escalation, persistence mechanisms, or data compromise, making comprehensive network security measures essential for protecting against exploitation.