CVE-2018-15839 in DIR-615
Summary
by MITRE
D-Link DIR-615 devices have a buffer overflow via a long Authorization HTTP header.
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Analysis
by VulDB Data Team • 07/21/2024
The CVE-2018-15839 vulnerability affects D-Link DIR-615 wireless routers and represents a critical buffer overflow condition that can be exploited through malformed HTTP requests. This vulnerability specifically targets the authentication handling mechanism within the router's web interface, where the device fails to properly validate the length of the Authorization HTTP header. The flaw exists in the firmware implementation of these networking devices, which are widely deployed in residential and small office environments. When an attacker crafts a malicious HTTP request containing an excessively long Authorization header, the device's processing routine overflows the allocated buffer space, potentially leading to arbitrary code execution or system crash. This vulnerability directly maps to CWE-121, which describes stack-based buffer overflow conditions where insufficient bounds checking allows data to overwrite adjacent memory locations. The attack surface is particularly concerning as it can be exploited remotely without requiring authentication, making it a significant threat to network security.
The technical implementation of this vulnerability stems from improper input validation within the HTTP server component of the DIR-615 firmware. When the web server processes incoming HTTP requests, it does not adequately check the length of the Authorization header before copying it into a fixed-size buffer. This allows an attacker to send a specially crafted request with an Authorization header exceeding the allocated buffer capacity, typically measured in bytes. The buffer overflow occurs during the parsing of the authentication credentials, where the device's software fails to implement proper bounds checking or input sanitization. The vulnerability is classified as a stack-based buffer overflow according to CWE-121, which occurs when data written to a stack buffer exceeds its allocated size, potentially corrupting adjacent memory regions including return addresses and function parameters. This type of vulnerability is particularly dangerous because it can be leveraged to execute arbitrary code on the affected device, effectively giving attackers complete control over the router's operations.
The operational impact of CVE-2018-15839 extends beyond simple service disruption, as it provides attackers with complete compromise of the affected D-Link DIR-615 devices. Once exploited, the vulnerability allows unauthorized individuals to gain administrative access to the router, potentially enabling them to modify network configurations, intercept traffic, redirect DNS requests, or establish persistent backdoors within the network infrastructure. The vulnerability affects devices running firmware versions prior to the patch release, leaving millions of routers exposed to potential exploitation. Network administrators face significant challenges in identifying and remediating this vulnerability, as the affected devices may be deployed in remote locations or managed by non-technical users who lack the knowledge to update firmware. The attack vector requires only a simple HTTP request to the router's web interface, making it easily exploitable by automated scanning tools and bots. This vulnerability aligns with ATT&CK technique T1072, which describes the use of software deployment tools and techniques to gain access to systems, and T1059, which covers command and control through application layer protocols.
Mitigation strategies for CVE-2018-15839 should prioritize immediate firmware updates from D-Link, as the vendor has released patches addressing this specific vulnerability. Network administrators should implement network segmentation and access control measures to limit exposure of these devices to untrusted networks, while also monitoring for suspicious HTTP traffic patterns that may indicate exploitation attempts. The implementation of web application firewalls and intrusion detection systems can help identify and block malicious requests targeting this vulnerability. Additional protective measures include disabling unnecessary services such as remote management access, changing default administrative credentials, and conducting regular vulnerability assessments of network infrastructure. Organizations should also consider implementing network monitoring solutions that can detect anomalous behavior patterns consistent with exploitation attempts. According to industry best practices and security frameworks, this vulnerability requires immediate attention due to its remote exploitability and the potential for complete system compromise. The remediation process should include verification of firmware updates through checksum validation, ensuring that devices are not running vulnerable versions, and maintaining updated inventories of all network devices to prevent similar vulnerabilities from remaining unpatched. Regular security audits and vulnerability scanning should be implemented to identify and address similar buffer overflow conditions in other network infrastructure components.