CVE-2017-7935 in mGuard
Summary
by MITRE
A Resource Exhaustion issue was discovered in Phoenix Contact GmbH mGuard firmware versions 8.3.0 to 8.4.2. An attacker may compromise the device's availability by performing multiple initial VPN requests.
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Analysis
by VulDB Data Team • 09/30/2020
The vulnerability identified as CVE-2017-7935 represents a critical resource exhaustion flaw within the mGuard firmware produced by Phoenix Contact GmbH. This security weakness affects specific versions ranging from 8.3.0 through 8.4.2, creating a significant risk to network availability and operational continuity. The issue stems from inadequate resource management during the initial VPN connection process, which allows malicious actors to exploit the device's limited computational and memory resources through repetitive connection attempts.
The technical implementation of this vulnerability manifests when an attacker systematically submits multiple initial VPN requests to the affected mGuard device. Each connection attempt consumes system resources including memory allocation, processing cycles, and network bandwidth. The firmware fails to properly implement rate limiting or connection throttling mechanisms, enabling an attacker to exhaust these resources through sustained or rapid-fire connection requests. This resource depletion ultimately leads to a denial of service condition where legitimate users cannot establish valid VPN connections to the device, effectively compromising its availability and operational integrity.
From an operational standpoint, this vulnerability presents severe implications for industrial control systems and network security infrastructures that rely on mGuard devices for secure remote access. The attack vector is particularly concerning because it requires minimal technical expertise to execute, making it accessible to threat actors with varying skill levels. Network administrators face the challenge of maintaining service availability while defending against this specific type of resource exhaustion attack. The impact extends beyond simple service disruption to potentially compromising the security posture of entire industrial networks that depend on these devices for remote management and monitoring capabilities.
The vulnerability aligns with CWE-400, which classifies resource exhaustion as a fundamental weakness in software design and implementation. This categorization reflects the core architectural flaw where the system fails to adequately manage resource allocation and consumption patterns. Additionally, the attack pattern corresponds to techniques documented in the ATT&CK framework under the denial of service category, specifically targeting network infrastructure components to disrupt legitimate service availability. Organizations utilizing affected mGuard firmware should implement immediate mitigation strategies including firmware updates to versions that address the resource management deficiencies, network-level rate limiting, and monitoring for unusual connection patterns that may indicate exploitation attempts.
The broader implications of this vulnerability highlight the critical need for robust resource management in embedded systems and industrial control environments. Security professionals must recognize that resource exhaustion attacks represent a sophisticated form of denial of service that can be particularly devastating in operational technology environments where system availability is paramount. The vulnerability demonstrates how seemingly routine network services can become attack vectors when proper resource management controls are absent, emphasizing the importance of comprehensive security testing and vulnerability assessment in industrial network infrastructure deployments.