CVE-2018-19239 in TEW-673GRU
Summary
by MITRE
TRENDnet TEW-673GRU v1.00b40 devices have an OS command injection vulnerability in the start_arpping function of the timer binary, which allows remote attackers to execute arbitrary commands via three parameters (dhcpd_start, dhcpd_end, and lan_ipaddr) passed to the apply.cgi binary through a POST request.
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Analysis
by VulDB Data Team • 06/20/2023
The CVE-2018-19239 vulnerability affects TRENDnet TEW-673GRU wireless routers running firmware version 1.00b40, presenting a critical operating system command injection flaw that enables remote attackers to execute arbitrary code on affected devices. This vulnerability resides within the timer binary's start_arpping function, where insufficient input validation allows malicious actors to inject OS commands through specifically crafted parameters. The attack vector involves sending a POST request to the apply.cgi binary with three vulnerable parameters: dhcpd_start, dhcpd_end, and lan_ipaddr, which are processed without proper sanitization or escaping mechanisms.
The technical implementation of this vulnerability demonstrates a classic command injection flaw that maps directly to CWE-77, which categorizes improper neutralization of special elements used in OS commands. The vulnerability occurs because the router's web interface fails to properly validate or sanitize user-supplied input before incorporating it into system commands executed by the underlying operating system. When the timer binary processes the timer configuration parameters through the apply.cgi interface, it constructs system commands by concatenating user input directly into command strings without appropriate escaping or filtering, creating a pathway for arbitrary code execution.
From an operational perspective, this vulnerability represents a severe security risk as it allows remote attackers to gain full control over affected routers without requiring authentication or physical access. Attackers can leverage this vulnerability to execute malicious commands such as installing backdoors, modifying router configurations, redirecting traffic, or establishing persistent access to the network. The impact extends beyond individual device compromise, as compromised routers can serve as entry points for broader network infiltration, potentially enabling lateral movement and data exfiltration across the entire local network. This vulnerability aligns with ATT&CK technique T1059.001 for command and scripting interpreter, where adversaries use legitimate system tools to execute malicious commands.
The mitigation strategies for CVE-2018-19239 should prioritize immediate firmware updates from TRENDnet to address the underlying command injection flaw. Network administrators should implement network segmentation to limit exposure and monitor for suspicious traffic patterns that may indicate exploitation attempts. Additional protective measures include disabling unnecessary web management interfaces, implementing firewall rules to restrict access to router management ports, and conducting regular security assessments of network infrastructure. The vulnerability also highlights the importance of secure coding practices, particularly input validation and command construction, which aligns with industry best practices outlined in OWASP Top Ten and NIST Cybersecurity Framework guidelines. Organizations should consider deploying intrusion detection systems to monitor for known exploitation patterns and ensure proper network access controls are in place to prevent unauthorized access to critical network devices.