CVE-2019-8985 in WF2880
Summary
by MITRE
On Netis WF2880 and WF2411 2.1.36123 devices, there is a stack-based buffer overflow that does not require authentication. This can cause denial of service (device restart) or remote code execution. This vulnerability can be triggered by a GET request with a long HTTP "Authorization: Basic" header that is mishandled by user_auth->user_ok in /bin/boa.
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Analysis
by VulDB Data Team • 07/19/2023
The vulnerability identified as CVE-2019-8985 represents a critical stack-based buffer overflow affecting Netis wireless routers including models WF2880 and WF2411 running firmware version 2.1.36123. This vulnerability exists within the web server component of these devices and demonstrates a fundamental flaw in input validation and memory management practices. The issue stems from improper handling of HTTP authentication headers, specifically the Authorization: Basic header, which creates a pathway for malicious actors to exploit the device's memory structure without requiring any authentication credentials. The vulnerability is particularly concerning because it operates at the application layer of the network stack and can be triggered through simple HTTP GET requests, making it accessible to anyone who can reach the device's web interface.
The technical exploitation mechanism involves the user_auth->user_ok function located within the /bin/boa binary, which serves as the web server application for these devices. When processing an HTTP GET request containing an excessively long Authorization: Basic header, the function fails to properly validate the input length before copying it into a fixed-size stack buffer. This classic buffer overflow condition allows an attacker to overwrite adjacent stack memory locations, potentially corrupting the program's execution flow. The vulnerability manifests as either a device restart due to the crash caused by memory corruption or more severely, remote code execution if the attacker can manipulate the overwritten memory to redirect program control flow. The stack-based nature of this overflow means that the attack can be executed without requiring any special privileges or authentication, as the web server processes all incoming HTTP requests regardless of their source.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as it provides a potential entry point for more sophisticated attacks within network environments. The affected devices operate as network infrastructure components that typically lack robust security measures, making them attractive targets for attackers seeking to establish persistent access or conduct lateral movement within compromised networks. According to the CWE catalog, this vulnerability maps directly to CWE-121, which describes stack-based buffer overflow conditions, and CWE-122, which covers heap-based buffer overflows, though the specific implementation here demonstrates stack-based exploitation. The attack vector aligns with ATT&CK technique T1210, which involves exploitation of remote services through the use of buffer overflow vulnerabilities. The lack of authentication requirements makes this particularly dangerous as it can be exploited by remote attackers without prior access to the device, potentially allowing for widespread compromise of network infrastructure.
Mitigation strategies for CVE-2019-8985 should prioritize immediate firmware updates from the vendor, as the vulnerability affects multiple device models and firmware versions. Network administrators should implement network segmentation and access controls to limit exposure of these devices to untrusted networks, while also monitoring for unusual traffic patterns that might indicate exploitation attempts. The vulnerability highlights the importance of input validation and proper memory management in embedded systems, particularly those handling network requests. Organizations should consider implementing network-based intrusion detection systems that can identify malformed HTTP requests containing overly long authorization headers, as this specific attack pattern can be detected through traffic analysis. Additionally, regular security assessments of network infrastructure devices are crucial to identify similar vulnerabilities in other embedded systems that may be similarly susceptible to stack-based buffer overflows due to inadequate input validation mechanisms. The vulnerability serves as a reminder of the critical need for secure coding practices in embedded systems and the potential consequences of insufficient bounds checking in network-facing applications.