CVE-2018-9285 in RT-AC66U
Summary
by MITRE
Main_Analysis_Content.asp in /apply.cgi on ASUS RT-AC66U, RT-AC68U, RT-AC86U, RT-AC88U, RT-AC1900, RT-AC2900, and RT-AC3100 devices before 3.0.0.4.384_10007; RT-N18U devices before 3.0.0.4.382.39935; RT-AC87U and RT-AC3200 devices before 3.0.0.4.382.50010; and RT-AC5300 devices before 3.0.0.4.384.20287 allows OS command injection via the pingCNT and destIP fields of the SystemCmd variable.
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Analysis
by VulDB Data Team • 02/27/2023
The vulnerability identified as CVE-2018-9285 represents a critical operating system command injection flaw affecting multiple ASUS router models including RT-AC66U, RT-AC68U, RT-AC86U, RT-AC88U, RT-AC1900, RT-AC2900, RT-AC3100, RT-N18U, RT-AC87U, RT-AC3200, and RT-AC5300 devices. This vulnerability exists within the Main_Analysis_Content.asp component of the /apply.cgi web interface, specifically targeting the SystemCmd variable that processes pingCNT and destIP parameters. The flaw allows remote attackers to execute arbitrary operating system commands on affected devices, potentially leading to complete system compromise and unauthorized access to network resources.
The technical implementation of this vulnerability stems from insufficient input validation and sanitization within the web application layer of the router's firmware. When users submit pingCNT and destIP values through the SystemCmd variable, the application fails to properly sanitize these inputs before incorporating them into system commands. This lack of proper input filtering creates an environment where maliciously crafted payloads can be interpreted and executed by the underlying operating system. The vulnerability is classified as CWE-78, which specifically addresses OS Command Injection, a well-known weakness that has been consistently exploited in various network device implementations. Attackers can leverage this vulnerability to execute commands such as shell commands, file system operations, or network reconnaissance activities directly on the router's operating system.
The operational impact of CVE-2018-9285 extends beyond simple command execution, potentially enabling attackers to establish persistent access to the affected network infrastructure. Once exploited, compromised routers can serve as entry points for broader network attacks, including man-in-the-middle operations, DNS hijacking, or as pivoting points for attacking internal network resources. The vulnerability affects firmware versions prior to specific build numbers, indicating that ASUS has released patches to address this issue. However, many devices may remain unpatched in production environments, particularly in enterprise or industrial settings where router updates are infrequent. The attack vector is particularly concerning because it requires no authentication, making it a significant threat to network security. According to ATT&CK framework, this vulnerability maps to T1059.001 for Command and Scripting Interpreter and T1071.004 for Application Layer Protocol: DNS, as attackers can leverage the compromised device for command execution and potentially DNS-based exfiltration.
Mitigation strategies for this vulnerability should prioritize immediate firmware updates from ASUS to the latest supported versions that contain patches for the command injection flaw. Network administrators should implement network segmentation and monitoring to detect anomalous command execution patterns originating from affected devices. Additional defensive measures include disabling unnecessary web management interfaces, implementing firewall rules to restrict access to router management ports, and conducting regular vulnerability assessments of network infrastructure. The vulnerability also highlights the importance of input validation and output encoding practices in embedded web applications, as recommended by OWASP and other security standards. Organizations should consider implementing intrusion detection systems to monitor for known exploit signatures and maintain up-to-date threat intelligence feeds to identify potential exploitation attempts against vulnerable router models. Regular security audits of network devices and implementation of robust patch management processes are essential to prevent similar vulnerabilities from being exploited in the future.