CVE-2019-13153 in TEW-827DRU
Summary
by MITRE
An issue was discovered in TRENDnet TEW-827DRU firmware before 2.05B11. There is a command injection in apply.cgi (exploitable with authentication) via the Private Port in Add Virtual Server.
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Analysis
by VulDB Data Team • 10/15/2023
The vulnerability identified as CVE-2019-13153 affects the TRENDnet TEW-827DRU wireless router firmware version 2.05B10 and earlier, representing a critical command injection flaw that can be exploited by authenticated attackers. This issue resides within the apply.cgi script, specifically in the handling of the Private Port parameter during the Add Virtual Server function. The vulnerability creates a dangerous condition where user-supplied input is directly incorporated into system commands without proper sanitization or validation, allowing malicious actors to execute arbitrary commands on the affected device. The exploitation requires prior authentication, which means an attacker must first obtain valid credentials to the router's web interface before attempting to leverage this vulnerability.
The technical implementation of this flaw falls under the CWE-77 category of Command Injection, where the application fails to properly escape or validate user input before passing it to underlying system commands. In this specific case, when a user configures virtual server settings through the web interface, the Private Port value is directly concatenated into shell commands without adequate input filtering. This creates a path where an attacker can inject malicious commands that will be executed with the privileges of the web server process, typically running with administrative privileges on the router. The vulnerability is particularly concerning because it allows for complete compromise of the device, enabling attackers to execute arbitrary code, modify device configuration, access network traffic, or even install persistent backdoors.
The operational impact of this vulnerability extends beyond simple device compromise, as it provides attackers with a foothold for broader network infiltration. Once authenticated, an attacker can leverage this command injection to perform various malicious activities including but not limited to port forwarding modifications, DNS hijacking, or even establishing reverse shells to maintain persistent access. The vulnerability also aligns with several techniques documented in the ATT&CK framework under the T1059.001 category for Command and Scripting Interpreter, where adversaries use legitimate system commands to execute malicious payloads. Additionally, this weakness enables potential lateral movement within networks as compromised routers often serve as gateways for internal network access, making the impact of exploitation significantly more severe than a simple device compromise.
Mitigation strategies for CVE-2019-13153 primarily focus on firmware updates, which TRENDnet has addressed in version 2.05B11 and subsequent releases. Organizations should immediately implement firmware updates across all affected TRENDnet TEW-827DRU devices to eliminate the command injection vulnerability. Network segmentation and access control measures should be implemented to limit administrative access to router interfaces, ensuring that only authorized personnel can reach the web management interface. Additional protective measures include disabling unnecessary services, implementing strong authentication mechanisms with multi-factor authentication, and monitoring network traffic for suspicious patterns that might indicate exploitation attempts. Security professionals should also consider implementing network intrusion detection systems that can identify and alert on command injection attempts targeting web interfaces, particularly focusing on unusual command execution patterns in router management services. Regular vulnerability assessments and penetration testing should be conducted to identify similar issues in other network infrastructure devices, as this type of vulnerability often indicates broader security weaknesses in embedded systems.