CVE-2020-9535 in DIR-615Jx10
Summary
by MITRE
fmwlan.c on D-Link DIR-615Jx10 devices has a stack-based buffer overflow via the formWlanSetup_Wizard webpage parameter when f_radius_ip1 is malformed.
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Analysis
by VulDB Data Team • 04/09/2024
The vulnerability identified as CVE-2020-9535 represents a critical stack-based buffer overflow flaw in the firmware of D-Link DIR-615Jx10 wireless routers. This vulnerability exists within the fmwlan.c source file and specifically manifests when processing the formWlanSetup_Wizard webpage parameter, particularly when the f_radius_ip1 field contains malformed input data. The issue stems from inadequate input validation and bounds checking within the wireless configuration handling routines of the router's web interface.
The technical implementation of this vulnerability allows an attacker to exploit a memory corruption flaw by submitting specially crafted malicious input through the web-based configuration interface. When the router processes the malformed f_radius_ip1 parameter, the insufficient buffer size validation causes data to overflow into adjacent memory locations on the stack, potentially leading to arbitrary code execution or system instability. This type of vulnerability falls under CWE-121 Stack-based Buffer Overflow, which is classified as a critical severity issue in the Common Weakness Enumeration catalog. The attack vector is particularly concerning as it operates through the standard web interface, making it accessible to remote attackers without requiring physical access to the device.
The operational impact of this vulnerability extends beyond simple system crashes or reboots, as it could potentially enable full system compromise. An attacker who successfully exploits this vulnerability could gain unauthorized access to the router's administrative functions, modify network configurations, intercept traffic, or establish persistent backdoors. The attack surface is significant given that the vulnerability resides in the wireless configuration setup process, which is frequently accessed by users during network deployment. This makes the device particularly vulnerable during initial setup phases or when administrators are configuring wireless security parameters. According to ATT&CK framework, this vulnerability maps to T1059.007 Command and Scripting Interpreter: PowerShell and T1078 Valid Accounts, as exploitation could lead to privilege escalation and persistent access to the network infrastructure.
Mitigation strategies for CVE-2020-9535 should prioritize immediate firmware updates from D-Link, as the vendor has released patches addressing this specific buffer overflow condition. Network administrators should also implement network segmentation and access controls to limit exposure of these devices to untrusted networks, while monitoring for suspicious web interface access patterns that might indicate exploitation attempts. Additional protective measures include disabling unnecessary wireless configuration interfaces when not actively needed, implementing strong authentication mechanisms, and conducting regular security assessments of network infrastructure components. The vulnerability highlights the importance of proper input validation and memory management in embedded systems, particularly those handling user-supplied data through web interfaces. Organizations should also consider implementing intrusion detection systems capable of identifying anomalous traffic patterns associated with buffer overflow exploitation attempts, and maintain comprehensive network monitoring to detect potential compromise of network access control devices.