CVE-2017-15636 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 new-time variable in the webfilter.lua file.
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Analysis
by VulDB Data Team • 12/22/2019
The vulnerability identified as CVE-2017-15636 affects TP-Link WVR, WAR, and ER series network devices, representing a critical command injection flaw that enables remote authenticated administrators to execute arbitrary code on affected systems. This vulnerability resides within the webfilter.lua file where the new-time variable is processed without adequate input validation or sanitization, creating a pathway for malicious command execution. The flaw specifically targets the web-based management interface of these devices, which are commonly deployed in enterprise and residential networking environments to provide firewall and web filtering capabilities.
The technical implementation of this vulnerability stems from improper handling of user-supplied input within the webfilter.lua script, which processes time-related configurations for web filtering policies. When an authenticated administrator accesses the web interface to modify time-based filtering parameters, the system fails to properly sanitize the new-time variable before incorporating it into system commands or shell executions. This classic command injection vulnerability allows attackers who have gained administrative credentials to inject malicious commands that execute with the privileges of the web server process, typically running with elevated system permissions. The vulnerability aligns with CWE-77 and CWE-89, which categorize command injection flaws and SQL injection respectively, though this instance specifically demonstrates command injection in a web application context.
The operational impact of CVE-2017-15636 is severe and multifaceted, potentially allowing attackers to gain complete control over affected network devices. Successful exploitation could enable attackers to modify firewall rules, redirect traffic, install malware, or establish persistent backdoors within the network infrastructure. Given that these devices often serve as primary network gateways, the compromise could lead to widespread network infiltration and data exfiltration capabilities. The vulnerability is particularly concerning because it requires only authenticated administrative access, which may be obtained through credential theft, social engineering, or other initial compromise techniques. Network defenders must recognize that once an attacker gains administrative privileges, they can leverage this vulnerability to escalate their access and potentially move laterally within the network environment.
Mitigation strategies for CVE-2017-15636 should prioritize immediate firmware updates from TP-Link, as the vendor has released patches addressing this specific vulnerability. Organizations should also implement network segmentation to limit the potential impact of device compromise and establish robust access control policies for administrative accounts. Monitoring for unusual administrative activities and implementing intrusion detection systems can help identify exploitation attempts. The vulnerability demonstrates the importance of input validation and proper sanitization in web applications, aligning with ATT&CK technique T1059.001 for command and script injection. Security teams should also consider implementing network access controls and regular vulnerability assessments to identify similar flaws in other network infrastructure components. Organizations using these devices should also review their administrative access procedures and implement multi-factor authentication where possible to reduce the risk of credential compromise leading to exploitation.