CVE-2022-36324 is a vulnerability identified in Siemens RUGGEDCOM RM1224 LTE(4G) EU devices, specifically affecting all firmware versions prior to V7.1.2. The core issue relates to improper handling of SSL/TLS parameter renegotiation. Normally, SSL/TLS renegotiation is a process that allows the client and server to renegotiate cryptographic parameters during an existing secure session. However, in this case, the affected devices do not implement adequate limits or throttling mechanisms on renegotiation requests. This flaw enables an unauthenticated remote attacker to bypass the device's TCP brute force prevention mechanisms. By exploiting this, an attacker can repeatedly trigger renegotiation requests without restriction, leading to excessive resource allocation on the device. This resource exhaustion can culminate in a denial of service (DoS) condition, rendering the device unresponsive or unable to process legitimate traffic for the duration of the attack. The vulnerability is classified under CWE-770, which concerns allocation of resources without limits or throttling, highlighting the root cause as a lack of proper resource management controls. Notably, exploitation does not require authentication or user interaction, increasing the attack surface. While no known exploits are currently reported in the wild, the vulnerability's nature suggests potential for disruption in operational environments relying on these devices for LTE connectivity and network resilience. Siemens has addressed this vulnerability in firmware version 7.1.2 and later, but no direct patch links are provided in the source information.

For European organizations, particularly those in critical infrastructure sectors such as energy, transportation, and industrial automation, the impact of this vulnerability could be significant. Siemens RUGGEDCOM RM1224 LTE(4G) devices are often deployed in harsh or remote environments to provide reliable LTE connectivity and network robustness. A successful DoS attack exploiting this vulnerability could disrupt network communications, leading to loss of monitoring, control, or data transmission capabilities. This disruption could affect operational continuity, safety systems, and real-time data flows essential for process control. The unauthenticated nature of the attack increases risk, as attackers do not need credentials or insider access. Additionally, the bypass of TCP brute force prevention mechanisms suggests that traditional network-level protections may be insufficient to mitigate the attack. While no known active exploitation exists, the vulnerability presents a latent risk that could be leveraged in targeted attacks or as part of broader campaigns aiming to degrade critical network infrastructure. The medium severity rating reflects the potential for significant availability impact without direct confidentiality or integrity compromise.

Organizations using Siemens RUGGEDCOM RM1224 LTE(4G) EU devices should prioritize upgrading all affected devices to firmware version 7.1.2 or later, where the vulnerability has been addressed. In the absence of immediate patching capability, network administrators should implement compensating controls such as: 1) Deploying network-level rate limiting and anomaly detection specifically tuned to identify and block excessive SSL/TLS renegotiation attempts. 2) Isolating vulnerable devices within segmented network zones with strict ingress filtering to limit exposure to untrusted networks. 3) Employing intrusion prevention systems (IPS) with custom signatures to detect patterns consistent with renegotiation abuse. 4) Monitoring device logs and network traffic for unusual SSL/TLS renegotiation activity to enable early detection of exploitation attempts. 5) Coordinating with Siemens support channels for any interim mitigation advice or firmware updates. Additionally, organizations should review and harden their overall TLS configurations to disable unnecessary renegotiation features if supported by the device firmware. These targeted measures go beyond generic patching advice and focus on reducing attack surface and improving detection capabilities.