CVE-2017-15635 in WVR
Summary
by MITRE
TP-Link WVR, WAR and ER devices allow remote authenticated administrators to execute arbitrary commands via command injection in the max_conn variable in the session_limits.lua file.
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Analysis
by VulDB Data Team • 12/22/2019
The vulnerability identified as CVE-2017-15635 affects TP-Link wireless access point and router devices including WVR, WAR, and ER series products. This represents a critical command injection flaw that enables remote authenticated administrators to execute arbitrary system commands on affected devices. The vulnerability stems from improper input validation within the session_limits.lua file where the max_conn variable is processed without adequate sanitization measures. The flaw allows an attacker with valid administrative credentials to inject malicious commands that will be executed with the privileges of the web server process, potentially compromising the entire network infrastructure.
The technical implementation of this vulnerability resides in the session_limits.lua script which handles connection limit configurations for the device's web management interface. When an authenticated administrator modifies the max_conn parameter through the web interface, the input is directly incorporated into system commands without proper sanitization or escaping mechanisms. This creates a classic command injection vulnerability that falls under CWE-77, which specifically addresses command injection flaws where untrusted data is concatenated with system commands. The vulnerability is particularly dangerous because it operates within the context of an authenticated administrative session, meaning that an attacker who has already gained administrative access or can obtain such credentials can leverage this flaw to escalate their privileges and execute arbitrary code on the device.
From an operational impact perspective, this vulnerability presents a significant risk to network security infrastructure as it allows attackers to execute arbitrary commands with the highest privileges available to the web server process. The attack surface is expanded because the vulnerability is accessible through the web interface, making it exploitable by anyone who can authenticate to the device's management interface. This creates a potential pathway for attackers to gain full control over the device, potentially enabling them to modify network configurations, redirect traffic, establish backdoors, or use the compromised device as a pivot point for further attacks within the network. The vulnerability also increases the risk of persistent access and can be leveraged for lateral movement attacks against other network segments.
Mitigation strategies for CVE-2017-15635 should focus on immediate remediation through official firmware updates provided by TP-Link, which would include proper input validation and sanitization of the max_conn parameter. Network administrators should also implement network segmentation to limit access to administrative interfaces and enforce strict access controls through multi-factor authentication. The use of network monitoring tools can help detect anomalous command execution patterns that might indicate exploitation attempts. Organizations should also consider implementing web application firewalls to filter malicious payloads before they reach the vulnerable application layer. This vulnerability aligns with ATT&CK technique T1059 which covers command and scripting interpreter, specifically targeting the execution of malicious commands through vulnerable interfaces. Regular security assessments and vulnerability scanning should be conducted to identify similar flaws in other network infrastructure components, as command injection vulnerabilities are commonly found in network device management interfaces and represent a persistent threat vector in enterprise environments.