CVE-2018-4853 in TC100
Summary
by MITRE
A vulnerability has been identified in SICLOCK TC100 (All versions) and SICLOCK TC400 (All versions). An attacker with network access to port 69/udp could modify the firmware of the device.
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Analysis
by VulDB Data Team • 04/03/2023
The vulnerability identified in SICLOCK TC100 and TC400 devices represents a critical security flaw in industrial time synchronization equipment that operates over network protocols. These devices are designed for use in critical infrastructure environments where precise timekeeping is essential for system coordination and security operations. The vulnerability stems from the TFTP (Trivial File Transfer Protocol) service running on UDP port 69, which is commonly used for firmware updates and configuration management in industrial devices. When an attacker gains network access to this specific port, they can exploit the insecure implementation of TFTP to modify the device firmware, effectively compromising the entire system. This vulnerability directly impacts the integrity and availability of time synchronization services that many industrial systems depend upon for proper operation and security enforcement.
The technical flaw manifests in the insecure handling of TFTP requests within these industrial time clock devices. The TFTP protocol lacks authentication mechanisms and encryption, making it inherently vulnerable to man-in-the-middle attacks and unauthorized modifications. Attackers can leverage this weakness by sending crafted TFTP packets to the device, potentially replacing legitimate firmware with malicious code or corrupting existing firmware to cause system failure. This vulnerability aligns with CWE-310, which addresses cryptographic weaknesses in protocols that lack proper authentication and encryption. The implementation does not properly validate file transfers or authenticate the source of firmware updates, creating an attack surface where any network-connected entity can manipulate the device's operational software. The lack of secure update mechanisms means that the device cannot distinguish between legitimate and malicious firmware modifications, fundamentally undermining its security posture.
The operational impact of this vulnerability extends beyond simple device compromise, affecting critical infrastructure reliability and security. Industrial environments that rely on precise time synchronization for network security logging, audit trails, and coordinated system operations face significant risks when these time clocks are compromised. An attacker who successfully modifies firmware can disrupt time synchronization across an entire facility, potentially causing cascading failures in systems that depend on synchronized timing for proper operation. This includes security systems that rely on timestamped logs, network protocols that require synchronized clocks, and industrial control systems where timing precision is critical. The vulnerability also enables persistent access to the network, as compromised time clocks can serve as footholds for further attacks. According to ATT&CK framework, this represents a technique under T1071.004 for application layer protocol usage and T1059.001 for command and scripting interpreter, as attackers can use the compromised device to maintain access and potentially escalate privileges. The impact is particularly severe in environments following NIST SP 800-82 guidelines for industrial control systems, where device integrity is paramount for operational technology security.
Mitigation strategies for this vulnerability require immediate implementation of network segmentation and access controls to restrict access to UDP port 69. Organizations should implement firewall rules that block external access to this port and ensure that only authorized personnel can initiate firmware updates through secure channels. The devices should be configured to use authenticated update mechanisms or secure TFTP implementations with proper authentication. Network administrators should also implement monitoring for unusual TFTP activity and establish secure firmware update procedures that verify digital signatures before installation. Regular security assessments should be conducted to ensure that no unauthorized modifications have occurred, and network access controls should be reviewed regularly to prevent unauthorized access. Organizations should consider implementing network access control lists that specifically block UDP port 69 from external network segments and ensure that firmware updates are only performed through authenticated channels using secure protocols such as HTTPS or SFTP. The vulnerability highlights the importance of secure device management practices and the need for industrial organizations to maintain robust security postures for all network-connected equipment, particularly those critical to operational technology infrastructure.