CVE-2018-11013 in DIR-816 A2 CN
Summary
by MITRE
Stack-based buffer overflow in the websRedirect function in GoAhead on D-Link DIR-816 A2 (CN) routers with firmware version 1.10B05 allows unauthenticated remote attackers to execute arbitrary code via a request with a long HTTP Host header.
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Analysis
by VulDB Data Team • 02/04/2020
The vulnerability CVE-2018-11013 represents a critical stack-based buffer overflow flaw discovered in the GoAhead web server component running on D-Link DIR-816 A2 routers with firmware version 1.10B05. This vulnerability exists within the websRedirect function, which processes HTTP Host headers during web requests. The flaw stems from inadequate input validation and bounds checking when handling the Host header parameter, creating a condition where maliciously crafted input can overwrite adjacent memory on the stack. This particular implementation vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions where insufficient bounds checking allows attackers to overwrite stack memory. The vulnerability affects routers operating in the consumer and small office environments, making it particularly dangerous as it can be exploited by unauthenticated remote attackers without requiring any prior access credentials or network privileges.
The technical exploitation of this vulnerability occurs when an attacker sends a specially crafted HTTP request containing an excessively long Host header value to the affected router. The websRedirect function fails to properly validate the length of the Host header before copying it into a fixed-size stack buffer, resulting in buffer overflow conditions that can corrupt the stack frame. This overflow can overwrite return addresses, saved registers, and other critical stack data structures, potentially allowing attackers to redirect program execution flow. The attack vector is particularly concerning because it requires no authentication and can be executed over the network, making it a prime candidate for automated exploitation. According to ATT&CK framework tactic T1210, this vulnerability enables adversaries to conduct remote code execution through exploitation of software vulnerabilities, while also mapping to T1059 which covers command and scripting interpreters as potential execution methods.
The operational impact of this vulnerability extends beyond simple remote code execution, as it can provide attackers with complete control over the affected router. Once exploited, attackers can modify router configurations, redirect traffic through malicious proxies, establish backdoors for persistent access, or use the compromised device as a launching point for attacks against other networked devices. The D-Link DIR-816 A2 model represents a popular consumer-grade router that typically serves as a gateway for home and small business networks, making the compromise of such devices particularly damaging. The vulnerability affects not only the router's web interface but can also potentially impact the underlying operating system and network services provided by the device. Network administrators should note that the affected firmware version 1.10B05 was widely distributed, meaning a significant number of devices could be vulnerable across multiple geographical regions, creating widespread exposure for this particular flaw.
Mitigation strategies for CVE-2018-11013 should prioritize immediate firmware updates from D-Link, as the vendor has released patches addressing this specific vulnerability. Organizations should also implement network segmentation and access controls to limit exposure of these devices to untrusted networks, while monitoring for suspicious traffic patterns that might indicate exploitation attempts. Network intrusion detection systems should be configured to detect unusually long HTTP Host headers, and administrators should consider disabling unnecessary web services on affected devices until patches are applied. The vulnerability demonstrates the importance of proper input validation and memory management in embedded systems, particularly in network appliances where remote exploitation capabilities can have far-reaching consequences. Security professionals should also consider implementing network monitoring solutions that can detect and alert on exploitation attempts targeting known buffer overflow vulnerabilities, as these attacks often follow predictable patterns that can be identified through network traffic analysis and anomaly detection systems.