CVE-2017-13772 in WR940N
Summary
by MITRE
Multiple stack-based buffer overflows in TP-Link WR940N WiFi routers with hardware version 4 allow remote authenticated users to execute arbitrary code via the (1) ping_addr parameter to PingIframeRpm.htm or (2) dnsserver2 parameter to WanStaticIpV6CfgRpm.htm.
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Analysis
by VulDB Data Team • 08/06/2024
The CVE-2017-13772 vulnerability affects TP-Link WR940N WiFi routers with hardware version 4 and represents a critical security flaw that enables remote authenticated attackers to execute arbitrary code on affected devices. This vulnerability stems from multiple stack-based buffer overflows present in the router's web interface handling mechanisms, specifically targeting two distinct input parameters within different HTML pages. The flaw exists in the firmware's handling of user-supplied data without proper bounds checking, creating exploitable conditions that can be leveraged by attackers who have already gained authentication credentials to the router's administrative interface.
The technical implementation of this vulnerability involves two primary attack vectors that demonstrate the router's insufficient input validation and memory management practices. The first vector targets the ping_addr parameter within the PingIframeRpm.htm page, while the second targets the dnsserver2 parameter in the WanStaticIpV6CfgRpm.htm page. Both parameters are processed without adequate buffer size checks, allowing attackers to overflow the allocated stack space and potentially overwrite adjacent memory locations. This type of vulnerability falls under CWE-121 Stack-based Buffer Overflow, which is classified as a critical weakness in software design that directly enables code execution attacks. The buffer overflow conditions occur during the parsing of user-provided input values that are directly incorporated into stack-based memory operations without proper sanitization or length verification.
The operational impact of CVE-2017-13772 extends beyond simple privilege escalation, as successful exploitation can result in complete device compromise and potential network infiltration. Once an attacker gains authenticated access to the router's administrative interface, they can craft malicious payloads that exploit the buffer overflow conditions to overwrite critical memory segments including return addresses and function pointers. This allows for arbitrary code execution with the privileges of the web server process, which typically runs with elevated permissions on the router. The vulnerability creates a persistent backdoor that can be used for various malicious activities including but not limited to man-in-the-middle attacks, DNS poisoning, traffic interception, and establishing covert communication channels. From an adversary perspective, this vulnerability aligns with ATT&CK technique T1059.007 for Command and Scripting Interpreter and T1068 for Exploitation for Privilege Escalation, making it particularly dangerous for network security.
Mitigation strategies for this vulnerability require immediate firmware updates from TP-Link to address the buffer overflow conditions in the affected router models. Network administrators should implement network segmentation and access control measures to limit the potential impact of successful exploitation, while also monitoring for unusual network traffic patterns that might indicate compromise. The vulnerability demonstrates the importance of input validation and proper memory management practices in embedded systems, particularly those handling user-supplied data through web interfaces. Organizations should conduct thorough vulnerability assessments of their network infrastructure to identify other potentially affected devices and implement robust patch management processes to ensure timely remediation of similar vulnerabilities. Security monitoring should include detection of suspicious parameter values in web interface requests and implementation of web application firewalls to prevent exploitation attempts. The presence of such vulnerabilities in consumer-grade networking equipment highlights the critical need for manufacturers to implement more rigorous security testing and code review processes during development phases, particularly for devices that handle network traffic and user input.