CVE-2020-15498 in RT-AC1900P
Summary
by MITRE
An issue was discovered on ASUS RT-AC1900P routers before 3.0.0.4.385_20253. The router accepts an arbitrary server certificate for a firmware update. The culprit is the --no-check-certificate option passed to wget tool used to download firmware update files.
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Analysis
by VulDB Data Team • 08/26/2020
The vulnerability identified as CVE-2020-15498 affects ASUS RT-AC1900P routers running firmware versions prior to 3.0.0.4.385_20253, representing a critical security flaw in the device's firmware update mechanism. This issue stems from the router's improper handling of SSL/TLS certificate validation during firmware upgrade processes, creating a significant attack surface that adversaries can exploit to compromise device integrity. The vulnerability specifically resides in how the router's update system interacts with the wget utility, which is commonly used for retrieving files over network protocols including https. The implementation fails to properly validate the authenticity of the certificate presented by the update server, leaving the device susceptible to man-in-the-middle attacks where malicious actors could intercept firmware updates and inject compromised code.
The technical root cause of this vulnerability maps directly to CWE-295, which addresses improper certificate validation in security protocols, and more specifically to CWE-310, which deals with cryptographic issues related to key management and certificate validation. The exploitation occurs through the use of the --no-check-certificate option within the wget command execution, effectively disabling SSL/TLS certificate verification. This configuration allows the router to accept any server certificate regardless of its validity, trust chain, or authenticity. From an operational perspective, this flaw undermines the fundamental security principle of secure firmware updates by creating a trust relationship with any server that can present a certificate, regardless of whether that server is legitimate or has been compromised.
The operational impact of this vulnerability extends beyond simple device compromise to encompass potential full system takeover and persistent backdoor installation. Attackers who can intercept network traffic between the router and its update servers can replace legitimate firmware images with malicious versions, effectively taking control of the device and potentially using it as a pivot point for broader network attacks. This vulnerability aligns with several tactics described in the MITRE ATT&CK framework, particularly those related to privilege escalation and persistence mechanisms. The compromised device could be used to establish command and control channels, perform network reconnaissance, or serve as a platform for launching attacks against other networked devices, making the impact of this vulnerability particularly severe in enterprise or home network environments where routers often serve as central points of connectivity and security control.
Organizations and individuals should immediately implement mitigations including updating to the patched firmware version 3.0.0.4.385_20253 or later, which properly validates SSL/TLS certificates during firmware updates. Network administrators should also consider implementing additional monitoring for unusual firmware update activities and ensure that all network traffic between routers and update servers is properly inspected for signs of tampering. The vulnerability demonstrates the critical importance of certificate validation in security-critical systems and serves as a reminder that disabling security features for convenience can create significant risks. Regular firmware update processes should be implemented with proper certificate validation checks, and network administrators should be vigilant about monitoring for any unauthorized changes to device configurations or firmware versions. The incident also highlights the need for robust supply chain security measures and proper secure communication protocols in network infrastructure devices to prevent similar vulnerabilities from arising in other network equipment.