CVE-2017-1000020 in ECos
Summary
by MITRE
SYN Flood or FIN Flood attack in ECos 1 and other versions embedded devices results in web Authentication Bypass. "eCos Embedded Web Servers used by Multiple Routers and Home devices, while sending SYN Flood or FIN Flood packets fails to validate and handle the packets and does not ask for any sign of authentication resulting in Authentication Bypass. An attacker can take complete advantage of this bug and take over the device remotely or locally. The bug has been successfully tested and reproduced in some versions of SOHO Routers manufactured by TOTOLINK, GREATEK and others."
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Analysis
by VulDB Data Team • 10/26/2019
The vulnerability identified as CVE-2017-1000020 represents a critical security flaw in eCos embedded web servers that are widely deployed in consumer and small office networking equipment. This vulnerability stems from inadequate packet validation mechanisms within the embedded web server implementation, specifically failing to properly handle SYN Flood and FIN Flood attack patterns that are commonly employed in network-level denial of service attacks. The flaw exists in the protocol handling layer where the web server fails to validate incoming network packets, creating a pathway for unauthorized access to device management interfaces. The vulnerability affects multiple router manufacturers including TOTOLINK and GREATEK, indicating a widespread issue within the embedded systems ecosystem. According to CWE classification, this vulnerability maps to CWE-200 Information Exposure and CWE-310 Cryptographic Issues, as the lack of proper authentication validation exposes system interfaces to unauthorized access.
The technical implementation of this vulnerability demonstrates a fundamental flaw in the network stack processing within the eCos embedded operating system. When the embedded web server receives malformed or attack-oriented packets, it fails to properly validate the packet sequence and state transitions that should normally occur during TCP connection establishment and termination. The server's inability to properly handle these network conditions creates a window of opportunity where authentication mechanisms can be bypassed entirely. This occurs because the web server does not enforce proper TCP state validation before allowing access to administrative interfaces, effectively allowing any remote or local attacker to access the device management console without proper credentials. The vulnerability specifically affects devices running eCos version 1 and subsequent versions, where the TCP/IP stack implementation lacks sufficient input validation and connection state management. From an operational perspective, this represents a severe privilege escalation vulnerability that can be exploited through network-based attacks.
The operational impact of CVE-2017-1000020 extends far beyond simple denial of service conditions, as it provides complete unauthorized access to affected devices. Attackers can leverage this vulnerability to gain full administrative control over routers and home networking equipment, potentially enabling them to modify network configurations, install malicious firmware, redirect traffic, or establish persistent backdoors. The vulnerability is particularly dangerous because it can be exploited remotely, meaning attackers do not require physical access to the devices to compromise them. The attack vector through SYN and FIN flood patterns allows for exploitation without requiring complex reconnaissance, as the vulnerability is triggered by normal network traffic patterns that occur during legitimate connection attempts. This makes the vulnerability particularly attractive to automated attack tools and increases the potential for widespread compromise across networks. The vulnerability's presence in SOHO routers and home devices creates a significant risk for both individual users and enterprise networks that may be connected to these devices.
Mitigation strategies for CVE-2017-1000020 must address both immediate operational concerns and long-term architectural improvements. Organizations should implement network-level protections such as rate limiting and connection tracking to reduce the effectiveness of SYN and FIN flood attacks that trigger the vulnerability. Network segmentation and firewall rules can help limit access to affected devices while patches are being deployed. The most effective long-term solution involves updating affected devices to newer versions of eCos that properly implement TCP state validation and packet handling. According to ATT&CK framework, this vulnerability maps to T1071.004 Application Layer Protocol: DNS and T1190 Exploit Public-Facing Application, as it represents an exploitation of web server vulnerabilities that can be leveraged for remote code execution and privilege escalation. Device manufacturers should implement proper input validation and state machine checks in their TCP/IP stack implementations, ensuring that all connection establishment and termination sequences are properly validated before granting access to management interfaces. Regular security assessments and network monitoring should be implemented to detect anomalous traffic patterns that may indicate exploitation attempts. The vulnerability serves as a reminder of the critical importance of proper protocol implementation in embedded systems and the need for comprehensive security testing of network infrastructure devices.