CVE-2018-12693 in TL-WA850RE
Summary
by MITRE
Stack-based buffer overflow in TP-Link TL-WA850RE Wi-Fi Range Extender with hardware version 5 allows remote authenticated users to cause a denial of service (outage) via a long type parameter to /data/syslog.filter.json.
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Analysis
by VulDB Data Team • 02/21/2020
The CVE-2018-12693 vulnerability represents a critical stack-based buffer overflow flaw discovered in the TP-Link TL-WA850RE Wi-Fi Range Extender firmware version 5. This vulnerability exists within the web interface handling of system log filtering parameters, specifically targeting the /data/syslog.filter.json endpoint. The flaw manifests when the device processes a malformed type parameter that exceeds the allocated stack buffer space, creating an exploitable condition that can be leveraged by remote authenticated attackers. The vulnerability is particularly concerning as it affects a widely deployed networking device that serves as a range extender for wireless networks, making it a potential target for attackers seeking to disrupt network connectivity for legitimate users.
The technical implementation of this buffer overflow occurs in the firmware's web server component that manages system log filtering functionality. When an authenticated user sends a crafted request containing an excessively long type parameter to the /data/syslog.filter.json endpoint, the device fails to properly validate the input length before copying it into a fixed-size stack buffer. This lack of proper bounds checking creates a classic stack-based buffer overflow condition where the excessive data overflows into adjacent memory locations, potentially corrupting the stack frame and causing unpredictable behavior. The vulnerability is classified under CWE-121 Stack-based Buffer Overflow, which is a fundamental memory safety issue that has been consistently identified as a critical threat in software security assessments.
From an operational perspective, this vulnerability enables remote authenticated attackers to induce a denial of service condition that effectively creates network outages for legitimate users. The impact extends beyond simple service disruption as the device may become unresponsive or crash entirely, requiring manual intervention for recovery. Network administrators face the challenge of maintaining connectivity for their wireless infrastructure while managing the risk of unauthorized users exploiting this vulnerability. The attack vector requires only authentication credentials, making it particularly dangerous as it can be exploited by insiders or compromised accounts. This vulnerability directly maps to attack techniques described in the MITRE ATT&CK framework under T1499 Disruption of Services, specifically targeting network infrastructure devices to create availability issues.
The mitigation strategies for CVE-2018-12693 primarily focus on firmware updates provided by TP-Link, which address the input validation issues in the affected web interface components. Network administrators should prioritize applying the latest firmware versions that contain patches for this vulnerability, as these updates typically include proper bounds checking and input sanitization measures. Additionally, implementing network segmentation and access controls can help reduce the attack surface by limiting which users can access the device's web interface. Regular vulnerability scanning and network monitoring should be employed to detect potential exploitation attempts, while maintaining up-to-date security patches across all network infrastructure components. The vulnerability highlights the importance of proper software security practices in embedded systems, particularly regarding input validation and memory management, as outlined in industry standards such as the OWASP Top Ten and NIST Cybersecurity Framework guidelines for securing network devices and IoT infrastructure.