CVE-2017-12754 in RT-AC88U
Summary
by MITRE
Stack buffer overflow in httpd in Asuswrt-Merlin firmware 380.67_0RT-AC5300 and earlier for ASUS devices and ASUS firmware for ASUS RT-AC5300, RT_AC1900P, RT-AC68U, RT-AC68P, RT-AC88U, RT-AC66U, RT-AC66U_B1, RT-AC58U, RT-AC56U, RT-AC55U, RT-AC52U, RT-AC51U, RT-N18U, RT-N66U, RT-N56U, RT-AC3200, RT-AC3100, RT_AC1200GU, RT_AC1200G, RT-AC1200, RT-AC53, RT-N12HP, RT-N12HP_B1, RT-N12D1, RT-N12+, RT_N12+_PRO, RT-N16, and RT-N300 devices allows remote attackers to execute arbitrary code on the router by sending a crafted http GET request packet that includes a long delete_offline_client parameter in the url.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 11/06/2019
The vulnerability CVE-2017-12754 represents a critical stack buffer overflow flaw discovered in the httpd daemon of Asuswrt-Merlin firmware versions up to 380.67_0RT-AC5300. This vulnerability affects a substantial range of ASUS router models including popular AC series devices such as RT-AC5300, RT-AC68U, RT-AC88U, and numerous others across various product lines. The flaw exists within the web server component that processes HTTP GET requests, specifically when handling the delete_offline_client parameter in URLs. The vulnerability is classified as a stack-based buffer overflow under CWE-121, which occurs when a program writes data beyond the bounds of a fixed-length stack buffer, potentially corrupting adjacent memory locations including return addresses and control data.
The technical exploitation of this vulnerability requires remote attackers to craft a malicious HTTP GET request containing an excessively long delete_offline_client parameter value. When the httpd daemon processes this malformed request, the insufficient input validation leads to buffer overflow conditions that can be leveraged to overwrite stack memory contents. This type of vulnerability falls under the ATT&CK technique T1203, which involves exploiting software vulnerabilities to gain remote code execution capabilities. The buffer overflow creates opportunities for attackers to manipulate the program's execution flow by overwriting return addresses or function pointers, potentially allowing arbitrary code execution with the privileges of the httpd process.
The operational impact of this vulnerability is severe as it enables remote code execution on affected routers, providing attackers with complete control over the network device. Once exploited, attackers can gain persistent access to the router's operating system, potentially using it as a pivot point for further network infiltration or as a command and control server. The affected devices operate as network infrastructure components that typically maintain persistent connections and may be accessible from external networks, making this vulnerability particularly dangerous. The vulnerability affects both the router's web interface and its underlying operating system, as the httpd daemon runs with elevated privileges to manage network configurations and firewall rules.
Mitigation strategies for CVE-2017-12754 should focus on immediate firmware updates from ASUS to versions containing patches addressing the buffer overflow. Network administrators should implement strict firewall rules to restrict external access to router management interfaces where possible, though this may not be feasible given the nature of router functionality. Additional protective measures include monitoring network traffic for suspicious GET requests with unusually long parameter values, implementing intrusion detection systems to identify potential exploitation attempts, and conducting regular vulnerability assessments of network infrastructure. The vulnerability demonstrates the importance of proper input validation and bounds checking in network services, aligning with security best practices outlined in NIST SP 800-144 and OWASP Top 10 security guidelines. Organizations should also consider segmenting network infrastructure and implementing network access controls to limit the potential impact of such vulnerabilities.