CVE-2020-14124 in AX3600
Summary
by MITRE • 09/16/2021
There is a buffer overflow in librsa.so called by getwifipwdurl interface, resulting in code execution on Xiaomi router AX3600 with ROM version =rom< 1.1.12.
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Analysis
by VulDB Data Team • 09/19/2021
The vulnerability identified as CVE-2020-14124 represents a critical buffer overflow condition within the librsa.so library component of Xiaomi router firmware, specifically affecting the AX3600 model with ROM versions prior to 1.1.12. This flaw exists within the getwifipwdurl interface which handles wireless password URL generation functionality. The buffer overflow occurs when the system processes input data through the cryptographic library functions without proper bounds checking, creating an exploitable condition that allows attackers to overwrite adjacent memory locations. The vulnerability manifests due to insufficient validation of input parameters passed to the RSA library functions, enabling malicious actors to craft specially formatted inputs that exceed the allocated buffer space.
The technical implementation of this vulnerability aligns with CWE-121, which describes heap-based buffer overflow conditions, and CWE-787, which covers out-of-bounds write vulnerabilities. The flaw operates at the application layer within the router's firmware ecosystem, specifically targeting the cryptographic processing module responsible for handling wireless network credentials. Attackers can exploit this condition by sending malformed requests to the getwifipwdurl interface, causing the system to execute arbitrary code with the privileges of the affected service. The attack vector requires network access to the router's web interface or API endpoints, making it particularly dangerous for devices accessible over the internet. This vulnerability demonstrates poor input validation practices and inadequate memory management within the embedded firmware environment, creating a pathway for remote code execution that could lead to complete system compromise.
The operational impact of CVE-2020-14124 extends beyond simple code execution to encompass full system takeover capabilities, including potential persistence mechanisms and lateral movement within network environments. Once exploited, attackers can gain unauthorized access to the router's administrative interface, modify network configurations, redirect traffic, or establish backdoors for continued access. The vulnerability affects devices running older ROM versions, making it particularly concerning for users who have not updated their firmware, as the default configuration remains exposed. This flaw also represents a significant risk to IoT security posture, as routers often serve as primary network gateways and are frequently overlooked in security assessments. The exploitation of this vulnerability could enable attackers to conduct man-in-the-middle attacks, DNS hijacking, or other advanced persistent threats that leverage the router's privileged network position.
Mitigation strategies for CVE-2020-14124 should prioritize immediate firmware updates to version 1.1.12 or later, which contain the necessary patches addressing the buffer overflow condition. Network administrators should implement firewall rules to restrict access to router management interfaces from untrusted networks, while also ensuring that default credentials are changed and access controls are properly configured. The implementation of network segmentation and monitoring solutions can help detect anomalous behavior indicative of exploitation attempts, including unusual traffic patterns or unauthorized configuration changes. Additionally, organizations should conduct vulnerability assessments to identify other potentially affected devices within their network infrastructure, as similar buffer overflow conditions may exist in other firmware components. The remediation process should also include regular firmware update policies and security awareness training for network administrators to ensure timely patch deployment and proper security maintenance practices are maintained across all networked devices.