CVE-2018-8835 in WebAccess HMI Designer
Summary
by MITRE
Double free vulnerabilities in Advantech WebAccess HMI Designer 2.1.7.32 and prior caused by processing specially crafted .pm3 files may allow remote code execution.
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Analysis
by VulDB Data Team • 01/31/2020
The vulnerability identified as CVE-2018-8835 represents a critical double free vulnerability affecting Advantech WebAccess HMI Designer version 2.1.7.32 and earlier. This flaw exists within the software's handling of specially crafted .pm3 files, which are used for project management and configuration within the human machine interface design environment. The vulnerability stems from improper memory management practices where the application fails to properly validate or handle memory allocation and deallocation sequences when processing malformed project files. This type of vulnerability falls under the Common Weakness Enumeration category CWE-415, which specifically addresses double free conditions where the same memory location is freed twice, potentially leading to memory corruption and arbitrary code execution. The attack vector is particularly concerning as it enables remote code execution through the delivery of malicious .pm3 files, making it a significant threat to industrial control systems and SCADA environments where Advantech WebAccess HMI Designer is commonly deployed.
The technical exploitation of this vulnerability occurs when an attacker crafts a malicious .pm3 file that triggers improper memory handling within the HMI Designer application. During the processing of such files, the software's memory management routines execute multiple free operations on the same memory block, creating a condition where subsequent memory operations may corrupt the heap structure or manipulate pointers in ways that allow code execution. This type of heap-based vulnerability is particularly dangerous in industrial environments where these systems often operate without proper network segmentation or intrusion detection measures. The double free condition creates opportunities for attackers to manipulate the program's execution flow through techniques such as heap spraying or pointer overwrites, potentially leading to complete system compromise. The vulnerability demonstrates a clear violation of secure coding practices and represents a failure in proper memory management validation within the application's file processing pipeline.
The operational impact of CVE-2018-8835 extends beyond simple remote code execution to encompass potential operational technology (OT) system compromise within industrial environments. Organizations utilizing Advantech WebAccess HMI Designer in manufacturing, energy, or critical infrastructure sectors face significant risk from this vulnerability, as it could enable attackers to gain unauthorized access to operational control systems. The remote nature of the exploit means that attackers do not require physical access to the systems, allowing for attacks from external networks or even through compromised supply chain components. This vulnerability particularly affects environments where industrial control systems are connected to corporate networks or the internet, creating attack surfaces that may not be properly secured according to industrial security standards. The potential for persistent access and lateral movement within these environments makes this vulnerability especially dangerous for organizations that do not maintain proper network segmentation between operational technology and information technology systems.
Mitigation strategies for CVE-2018-8835 must address both immediate remediation and long-term security posture improvements. The primary recommendation involves upgrading to a patched version of Advantech WebAccess HMI Designer, as this resolves the underlying memory management issues that create the double free condition. Organizations should also implement network segmentation to isolate industrial control systems from general corporate networks, following the principle of least privilege and reducing the attack surface for such remote exploitation attempts. Additionally, security controls such as network access control lists, intrusion detection systems, and regular vulnerability assessments should be deployed to monitor for potential exploitation attempts. The vulnerability highlights the importance of secure coding practices and memory management validation in industrial software, emphasizing the need for comprehensive application security testing including fuzzing and memory corruption vulnerability analysis. Organizations should also consider implementing application whitelisting controls to prevent unauthorized execution of potentially malicious .pm3 files and maintain regular security updates for all industrial control system components to address similar vulnerabilities in the future.