CVE-2021-27140 in HG6245D
Summary
by MITRE • 02/11/2021
An issue was discovered on FiberHome HG6245D devices through RP2613. It is possible to find passwords and authentication cookies stored in cleartext in the web.log HTTP logs.
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Analysis
by VulDB Data Team • 02/28/2021
The vulnerability identified as CVE-2021-27140 affects FiberHome HG6245D routers running firmware version RP2613 and potentially other similar devices in the FiberHome product line. This issue represents a critical security flaw that exposes sensitive authentication credentials through improper logging practices. The vulnerability stems from the device's web server implementation which fails to sanitize authentication tokens and passwords before writing them to log files, creating a persistent security risk for users who may not be aware of the exposure.
The technical flaw manifests in the device's logging mechanism where HTTP requests containing authentication cookies and password parameters are written to web.log files without proper obfuscation or filtering. This cleartext exposure occurs during normal device operation when users authenticate to the router's web interface, making the vulnerability particularly dangerous as it can be exploited by anyone with access to the device's file system or log files. The flaw aligns with CWE-532, which describes information exposure through log files, and represents a classic case of insufficient input sanitization in web applications. The vulnerability allows attackers to extract authentication credentials that can be used to gain unauthorized administrative access to the router, effectively compromising the entire network security posture.
The operational impact of this vulnerability extends beyond simple credential theft to encompass complete network compromise. Once an attacker obtains the cleartext passwords and authentication cookies from the web.log files, they can impersonate legitimate users and administrators to access the router's configuration interface. This access enables attackers to modify network settings, install malware, redirect traffic, or establish persistent backdoors within the network infrastructure. The vulnerability affects the principle of least privilege as it allows unauthorized access to network management functions that should be restricted to authorized personnel only. From an attack framework perspective, this vulnerability maps to multiple ATT&CK techniques including credential access through log file collection and privilege escalation via administrative access, making it particularly dangerous for enterprise and home network environments.
Mitigation strategies for CVE-2021-27140 require both immediate and long-term approaches to address the root cause. Organizations should immediately disable or restrict access to web.log files on affected devices, implement proper log sanitization protocols, and rotate authentication credentials for all devices. Network administrators should conduct thorough vulnerability assessments to identify other potentially affected devices in their inventory and ensure proper network segmentation to limit the impact of credential compromise. The recommended remediation includes firmware updates from FiberHome if available, or implementing network monitoring solutions that can detect unauthorized access attempts to log files. Additionally, organizations should establish logging policies that prevent sensitive data from being written to persistent storage and implement regular log file audits to identify potential exposure risks. The vulnerability highlights the importance of secure coding practices and proper input validation in network device software development, particularly in handling authentication tokens and sensitive information within web applications.