CVE-2019-5148 in AWK-3131A
Summary
by MITRE
An exploitable denial-of-service vulnerability exists in ServiceAgent functionality of the Moxa AWK-3131A, firmware version 1.13. A specially crafted packet can cause an integer underflow, triggering a large memcpy that will access unmapped or out-of-bounds memory. An attacker can send this packet while unauthenticated to trigger this vulnerability.
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Analysis
by VulDB Data Team • 04/02/2024
The CVE-2019-5148 vulnerability represents a critical denial-of-service flaw within the Moxa AWK-3131A industrial networking device, specifically affecting the ServiceAgent functionality in firmware version 1.13. This vulnerability demonstrates a classic integer underflow condition that can be exploited to cause system instability and complete service disruption. The affected device operates within industrial control systems and network infrastructure environments where reliability and continuous operation are paramount, making this vulnerability particularly concerning for operational technology environments. The vulnerability exists in the packet processing logic of the ServiceAgent component, which handles network communications and service requests from external entities.
The technical exploitation of this vulnerability occurs through a carefully crafted network packet that triggers an integer underflow condition within the device's memory management routines. When the malformed packet is received, it causes an integer underflow that subsequently leads to a large memcpy operation attempting to access memory locations that are either unmapped or out-of-bounds. This memory access violation results in the device experiencing a crash or complete system failure, effectively rendering the network appliance unavailable for legitimate operations. The integer underflow specifically occurs in the boundary checking logic where unsigned integer arithmetic fails to properly validate input parameters, leading to unexpected memory access patterns that bypass normal security and validation mechanisms.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise industrial network stability and operational continuity. In industrial environments where the Moxa AWK-3131A serves as a critical networking component for connecting field devices, sensors, and control systems, an unauthenticated denial-of-service attack can result in significant production downtime and operational losses. The vulnerability's accessibility from unauthenticated network connections makes it particularly dangerous as attackers can exploit it without requiring any credentials or prior access to the system. This characteristic aligns with ATT&CK technique T1499.001 for network denial-of-service attacks, where adversaries target network infrastructure to disrupt operations. The vulnerability also relates to CWE-191, which specifically addresses integer underflow conditions, and CWE-121, which covers stack-based buffer overflow conditions that can result from improper integer handling.
Mitigation strategies for CVE-2019-5148 should focus on both immediate defensive measures and long-term system hardening approaches. Network administrators should implement firewall rules and access control lists to restrict access to the affected ServiceAgent functionality, particularly blocking unnecessary network traffic that could trigger the vulnerability. Device firmware updates from Moxa should be applied immediately to address the underlying integer underflow condition in the ServiceAgent implementation. Network segmentation strategies should be employed to isolate critical industrial systems from general network access, reducing the attack surface available to potential exploiters. Additionally, monitoring and intrusion detection systems should be configured to detect unusual packet patterns that might indicate exploitation attempts, providing early warning capabilities for potential attacks targeting this vulnerability. The vulnerability also highlights the importance of proper input validation and integer arithmetic handling in embedded systems, emphasizing the need for comprehensive security testing during development phases to prevent similar issues in future implementations.