CVE-2021-21906 in Metal Detectors iC Module CMA
Summary
by MITRE • 12/22/2021
Stack-based buffer overflow vulnerability exists in how the CMA readfile function of Garrett Metal Detectors iC Module CMA Version 5.0 is used at various locations. The Garrett iC Module exposes an authenticated CLI over TCP port 6877. This interface is used by a secondary GUI client, called “CMA Connect”, to interact with the iC Module on behalf of the user. Every time a user submits a password to the CLI password prompt, the buffer containing their input is passed as the password parameter to the checkPassword function.
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Analysis
by VulDB Data Team • 12/26/2021
The vulnerability described in CVE-2021-21906 represents a critical stack-based buffer overflow within the Garrett Metal Detectors iC Module CMA Version 5.0 system architecture. This flaw manifests in the CMA readfile function where improper input validation occurs during password authentication processes. The iC Module operates with an authenticated command-line interface accessible through TCP port 6877, creating a direct attack surface that adversaries can exploit to gain unauthorized system access. The vulnerability specifically impacts the authentication mechanism where user credentials are processed through the checkPassword function, making it a prime target for privilege escalation attacks.
The technical implementation of this vulnerability stems from inadequate bounds checking within the password handling routine of the CMA module. When users submit passwords through the authenticated CLI interface, the input string is directly passed to the checkPassword function without proper size validation or buffer boundary enforcement. This design flaw allows attackers to overflow the allocated stack buffer space, potentially overwriting adjacent memory locations including return addresses and function pointers. The CWE-121 classification applies directly to this vulnerability as it involves stack-based buffer overflow conditions where insufficient space is allocated for data processing. The attack vector is particularly concerning because it operates over a network interface that requires authentication, meaning that an attacker must first establish valid credentials before exploiting the buffer overflow, but once successful, could potentially execute arbitrary code with elevated privileges.
The operational impact of this vulnerability extends beyond simple authentication bypass scenarios and represents a significant threat to physical security infrastructure. The iC Module serves as a critical component in metal detection systems used across various security-sensitive environments including airports, government facilities, and corporate campuses. An attacker who successfully exploits this vulnerability could potentially gain complete control over the device's operational functions, manipulate detection parameters, or even disable security systems entirely. The use of CMA Connect as a secondary GUI client means that the attack surface is expanded beyond direct CLI access, as the vulnerability could be triggered through the graphical interface as well. This creates multiple attack pathways and increases the overall risk profile of the system. The ATT&CK framework classification for this vulnerability would include privilege escalation techniques and remote code execution capabilities, making it particularly dangerous in environments where these devices are connected to critical infrastructure networks.
Mitigation strategies for CVE-2021-21906 should prioritize immediate firmware updates from Garrett Metal Detectors, as the vendor would have likely released patches addressing the buffer overflow conditions. Network segmentation should be implemented to isolate the iC Module from general network access, limiting the attack surface and preventing lateral movement. Access controls should be strictly enforced through the use of strong authentication mechanisms and monitoring of CLI access attempts. Additionally, network traffic monitoring should be deployed to detect unusual patterns that might indicate exploitation attempts on TCP port 6877. Regular vulnerability assessments should be conducted to identify similar buffer overflow conditions in other system components, as this vulnerability type often indicates broader code quality issues within the software architecture. The implementation of input validation controls and address space layout randomization (ASLR) techniques would provide additional layers of protection against similar exploitation attempts. Organizations should also consider implementing intrusion detection systems specifically configured to monitor for exploitation attempts targeting known buffer overflow vulnerabilities in security equipment.