CVE-2016-9683 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 'extensionsettings' CGI (/cgi-bin/extensionsettings) component responsible for handling some of the server's internal configurations. The CGI application doesn't properly escape the information it's passed when processing a particular multi-part form request involving scripts. The filename of the 'scriptname' variable is read in unsanitized 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. This is SonicWall Issue ID 181195.
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Analysis
by VulDB Data Team • 07/29/2024
The CVE-2016-9683 vulnerability represents a critical remote command injection flaw in SonicWall's Secure Remote Access server version 8.1.0.2-14sv, specifically within the web administrative interface's extensionsettings CGI component. This vulnerability resides in the /cgi-bin/extensionsettings endpoint which handles internal server configuration processing, making it a prime target for attackers seeking unauthorized access to network infrastructure. The flaw stems from inadequate input sanitization practices where user-supplied data is directly processed without proper escaping or validation before being passed to system execution functions. The vulnerability manifests when processing multi-part form requests involving scriptname variables, creating a direct pathway for malicious command execution. This issue falls under CWE-77 which categorizes command injection vulnerabilities, and aligns with ATT&CK technique T1059.001 for command and scripting interpreter, demonstrating how unvalidated inputs can lead to arbitrary code execution in web applications.
The technical implementation of this vulnerability exploits the insecure handling of the scriptname parameter through a dangerous call to the system() function without proper input sanitization. When an attacker submits a maliciously crafted multi-part form request containing specially crafted scriptname values, the application processes these inputs directly without proper validation or escaping mechanisms. This creates a scenario where attacker-controlled commands can be executed with the privileges of the nobody user account, which is typically the least privileged user account for web services. The vulnerability's exploitation path is particularly concerning because it allows remote attackers to gain shell access to the target system, potentially enabling further lateral movement within the network. The use of the nobody account as the execution context limits the immediate impact but still provides a foothold for more sophisticated attacks, as this account may have access to network services and configuration files that could be leveraged for privilege escalation.
The operational impact of this vulnerability extends beyond simple unauthorized access, as it fundamentally compromises the integrity and confidentiality of the SonicWall Secure Remote Access server. Attackers who successfully exploit this vulnerability can execute arbitrary commands on the target system, potentially leading to complete system compromise, data exfiltration, or disruption of network services. The vulnerability affects organizations that rely on SonicWall's secure remote access solutions, which are commonly deployed in enterprise environments for remote access management and network security. The remote nature of the exploit means that attackers can target these systems from outside the network perimeter, making the vulnerability particularly dangerous for organizations with remote access requirements. This type of vulnerability also undermines the trust model of the security infrastructure, as it allows attackers to bypass the very protections that the SonicWall appliance is designed to provide, potentially enabling further attacks against internal network resources.
Mitigation strategies for CVE-2016-9683 should focus on immediate remediation through official SonicWall security patches and updates, as well as network-level protections to prevent exploitation attempts. Organizations should implement network segmentation to limit access to the affected web interface, ensuring that only authorized administrative personnel can reach the vulnerable CGI endpoint. Input validation and sanitization mechanisms should be strengthened at the application level to prevent similar vulnerabilities in other components, with particular attention to any functions that directly execute system commands. Security monitoring should be enhanced to detect unusual patterns in form submissions or command execution attempts, and network traffic analysis should be employed to identify potential exploitation attempts. The vulnerability demonstrates the critical importance of proper input validation in web applications, aligning with industry best practices such as those outlined in the OWASP Top Ten and NIST cybersecurity guidelines. Regular security assessments and vulnerability scanning should be conducted to identify similar issues in other network infrastructure components, as this vulnerability type remains prevalent in web applications due to insufficient sanitization of user inputs.