CVE-2016-0858 in WebAccess
Summary
by MITRE
Race condition in Advantech WebAccess before 8.1 allows remote attackers to execute arbitrary code or cause a denial of service (buffer overflow) via a crafted request.
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Analysis
by VulDB Data Team • 07/23/2018
The vulnerability identified as CVE-2016-0858 represents a critical race condition flaw discovered in Advantech WebAccess software versions prior to 8.1. This vulnerability resides within the industrial automation and SCADA (Supervisory Control and Data Acquisition) monitoring platform that is widely deployed in critical infrastructure environments including manufacturing facilities, power plants, and water treatment systems. The race condition manifests during the processing of network requests, creating a temporal window where concurrent operations can interfere with each other, potentially leading to unpredictable behavior and system compromise. The flaw specifically affects the web-based management interface of Advantech WebAccess, which serves as the primary means for operators to monitor and control industrial processes through standard web browsers. This makes the vulnerability particularly dangerous as it can be exploited remotely without requiring physical access to the industrial control systems, aligning with attack patterns described in the MITRE ATT&CK framework under the T1190 technique for exploiting vulnerabilities in remote services.
The technical implementation of this race condition involves a buffer overflow scenario that occurs when the software processes specially crafted HTTP requests sent over the network. The flaw arises from improper synchronization mechanisms within the request handling code, where multiple threads or processes attempt to access shared memory resources simultaneously without adequate locking or validation. When an attacker sends a malformed request containing oversized data payloads or carefully constructed parameters, the system's memory management routines fail to properly validate input sizes before copying data into fixed-length buffers. This creates a situation where the buffer overflow can overwrite adjacent memory locations, potentially corrupting program execution flow or allowing attackers to inject and execute arbitrary code within the context of the WebAccess service. The vulnerability is classified as a CWE-367 weakness, specifically a Time-of-Check to Time-of-Use (TOCTOU) race condition, where the system checks for valid input parameters but fails to validate them again before actual processing occurs. The buffer overflow aspect of this vulnerability is further exacerbated by the fact that the affected WebAccess service typically runs with elevated privileges, potentially allowing successful exploitation to result in complete system compromise.
The operational impact of this vulnerability extends far beyond simple denial of service conditions, as it provides attackers with the capability to execute arbitrary code on industrial control systems. In critical infrastructure environments, this could lead to catastrophic consequences including process disruption, data manipulation, or even physical damage to equipment. The remote exploitability means that attackers can target these systems from anywhere on the internet, without requiring proximity or specialized access methods that would normally be required for industrial control system compromise. The vulnerability affects organizations across multiple sectors including energy, water, manufacturing, and transportation, where the reliability and security of SCADA systems is paramount to operational continuity and safety. The potential for cascading failures exists when compromised systems are part of larger networked industrial ecosystems, where unauthorized access to one system could potentially provide lateral movement capabilities to other connected systems. Organizations implementing the affected Advantech WebAccess versions face significant risk exposure, particularly those with limited cybersecurity resources or insufficient network segmentation to isolate industrial control systems from general enterprise networks.
Mitigation strategies for CVE-2016-0858 require immediate action to upgrade to Advantech WebAccess version 8.1 or later, which includes proper synchronization mechanisms and input validation fixes. Network administrators should implement robust firewall rules to restrict access to WebAccess management interfaces, limiting connectivity to only trusted administrative workstations and implementing network segmentation to isolate industrial control systems from general enterprise networks. The principle of least privilege should be applied to all WebAccess service accounts, ensuring that they operate with minimal required permissions and that access is strictly controlled through proper authentication mechanisms. Regular security assessments and vulnerability scanning should be conducted to identify any remaining instances of older WebAccess versions within industrial environments, as the vulnerability may persist in legacy systems or backup configurations. Additionally, organizations should implement network monitoring solutions capable of detecting anomalous traffic patterns that might indicate exploitation attempts, and establish incident response procedures specifically tailored to industrial control system security incidents. The remediation process should include thorough testing of updated software in controlled environments before deployment to production systems to ensure that the security patches do not introduce compatibility issues with existing industrial processes. Organizations should also consider implementing additional security controls such as intrusion detection systems specifically configured to monitor for known attack patterns targeting SCADA and industrial control systems, as outlined in various cybersecurity frameworks including NIST SP 800-84 and IEC 62443 standards.