CVE-2018-7761 in Modicon M340
Summary
by MITRE
A vulnerability exists in the HTTP request parser in Schneider Electric's Modicon M340, Modicon Premium, Modicon Quantum PLC, BMXNOR0200 which could allow arbitrary code execution.
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Analysis
by VulDB Data Team • 01/27/2020
The vulnerability identified as CVE-2018-7761 represents a critical security flaw within the HTTP request parsing functionality of Schneider Electric's industrial programmable logic controllers. This vulnerability affects multiple models including the Modicon M340, Modicon Premium, Modicon Quantum PLC, and BMXNOR0200 units, which are widely deployed in industrial control systems and critical infrastructure environments. The flaw resides in how these devices process incoming HTTP requests, creating a potential entry point for malicious actors to compromise the operational technology infrastructure.
The technical implementation of this vulnerability stems from inadequate input validation within the HTTP request parser component. When the affected PLCs receive specially crafted HTTP requests, the parsing mechanism fails to properly sanitize or validate the incoming data, leading to a potential buffer overflow condition or other memory corruption issues. This parsing error creates an opportunity for attackers to inject malicious code that can be executed within the context of the PLC's operating system. The vulnerability is particularly concerning because it allows for arbitrary code execution, meaning an attacker could potentially gain complete control over the industrial control device and its operations.
The operational impact of this vulnerability extends beyond simple network access, as these PLCs form the backbone of industrial automation systems controlling critical processes in manufacturing, energy, and other essential sectors. An attacker exploiting this vulnerability could potentially disrupt production processes, manipulate industrial control signals, or even cause physical damage to equipment. The attack surface is significant given that these devices are often deployed in environments with limited network segmentation and may have direct access to critical industrial processes. The vulnerability also presents challenges for industrial security teams as it may be difficult to detect due to the legitimate nature of HTTP traffic, making it harder to distinguish between normal operations and malicious activity.
Mitigation strategies for CVE-2018-7761 should prioritize immediate firmware updates from Schneider Electric, as the vendor has released patches addressing this specific vulnerability. Organizations should implement network segmentation to limit direct access to these industrial control devices from external networks, utilizing firewalls and access control lists to restrict HTTP traffic to only necessary administrative interfaces. Network monitoring should be enhanced to detect unusual HTTP request patterns that might indicate exploitation attempts, with particular attention to malformed requests or unexpected traffic volumes. The vulnerability aligns with CWE-121, which addresses stack-based buffer overflow conditions, and represents a potential pathway for techniques described in the ATT&CK framework under initial access and execution phases, particularly targeting industrial control systems through web-based attack vectors. Organizations should also consider implementing network intrusion detection systems specifically configured to identify patterns associated with HTTP request manipulation attacks against industrial control equipment.