CVE-2023-43478 in Smart Modem Gen 2
Summary
by MITRE • 09/20/2023
fake_upload.cgi on the Telstra Smart Modem Gen 2 (Arcadyan LH1000), firmware versions < 0.18.15r, allows unauthenticated attackers to upload firmware images and configuration backups, which could allow them to alter the firmware or the configuration on the device, ultimately leading to code execution as root.
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Analysis
by VulDB Data Team • 10/13/2023
The vulnerability identified as CVE-2023-43478 affects the Telstra Smart Modem Gen 2 running firmware versions prior to 0.18.15r, specifically targeting the fake_upload.cgi component within the device's web interface. This represents a critical security flaw that undermines the integrity and confidentiality of network infrastructure devices. The vulnerability exists in the authentication mechanism of the modem's web management interface, where the fake_upload.cgi script fails to properly validate user credentials before permitting file upload operations. The absence of proper authentication checks creates an exploitable pathway for malicious actors to bypass security controls and gain unauthorized access to the device's core functionality.
The technical implementation of this vulnerability stems from improper access control mechanisms within the web application layer of the modem's firmware. The fake_upload.cgi script operates without requiring authentication, allowing any remote attacker to submit firmware images or configuration backup files directly to the device's file system. This flaw aligns with CWE-287, which addresses improper authentication issues in software systems, and represents a classic case of insufficient authorization checks. The vulnerability's impact is amplified by the fact that successful exploitation enables attackers to upload malicious firmware images that can execute with root privileges, effectively providing complete control over the device's operations and network functionality.
The operational consequences of this vulnerability extend beyond simple unauthorized access, as it creates a persistent threat vector for attackers seeking to compromise network infrastructure. Once an attacker successfully uploads a malicious firmware image, they can execute arbitrary code with the highest privileges available on the device, potentially enabling them to modify network configurations, establish backdoors, or redirect network traffic. This capability directly maps to ATT&CK technique T1059, which involves executing malicious code through command and scripting interpreters, and T1547, which focuses on establishing persistence mechanisms. The vulnerability essentially transforms a consumer-grade modem into a potential command and control node for larger network attacks, particularly concerning in environments where such devices serve as network gateways or access points.
Mitigation strategies for CVE-2023-43478 must prioritize immediate firmware updates to version 0.18.15r or later, which contain the necessary authentication fixes to prevent unauthorized file uploads. Network administrators should also implement network segmentation to limit access to these devices, ensuring that only authorized personnel can reach the modem's management interface. Additional protective measures include disabling unnecessary web management interfaces when not in use, implementing strong access controls through firewalls, and conducting regular security audits of network infrastructure devices. Organizations should also consider deploying intrusion detection systems to monitor for suspicious file upload activities and maintain comprehensive network monitoring to detect potential exploitation attempts. The vulnerability demonstrates the critical importance of maintaining up-to-date firmware for network infrastructure devices and highlights the need for robust security practices in securing consumer-grade networking equipment that often operates with elevated privileges within corporate networks.