CVE-2020-6083 in Flex IO 1794-AENT-B
Summary
by MITRE • 10/14/2020
An exploitable denial of service vulnerability exists in the ENIP Request Path Port Segment functionality of Allen-Bradley Flex IO 1794-AENT/B. A specially crafted network request can cause a loss of communications with the device resulting in denial-of-service. An attacker can send a malicious packet to trigger this vulnerability.
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Analysis
by VulDB Data Team • 11/19/2020
The CVE-2020-6083 vulnerability represents a critical denial of service flaw within Allen-Bradley Flex IO 1794-AENT/B industrial network devices that operates at the Ethernet/IP protocol layer. This vulnerability specifically targets the ENIP Request Path Port Segment functionality, which is fundamental to how these industrial devices communicate within automation networks. The affected device serves as a crucial component in industrial control systems, acting as a network interface that connects various field devices to the broader control network. The vulnerability stems from improper input validation within the device's Ethernet/IP implementation, where the system fails to properly handle malformed or crafted network requests that target the path port segment functionality.
The technical exploitation of this vulnerability occurs when an attacker crafts a malicious network packet that specifically targets the ENIP Request Path Port Segment processing logic within the Flex IO device. This flaw manifests as a buffer over-read condition or improper memory handling when the device attempts to parse and process the malformed request. The vulnerability is classified under CWE-129 as an insufficient input validation issue, where the device does not adequately verify the structure and content of incoming network requests before processing them. The device's failure to properly validate the path segment information in the ENIP request leads to a state where the communication channel becomes unstable and eventually terminates, resulting in complete loss of communication with the device. This type of vulnerability is particularly dangerous in industrial environments where continuous operation is critical for process control and safety systems.
The operational impact of CVE-2020-6083 extends beyond simple network disruption to potentially compromise entire industrial control processes. When the device becomes unresponsive, it creates a cascading effect throughout the automation network, as other devices may lose communication with the affected Flex IO module. This vulnerability directly impacts the availability aspect of the CIA triad, making it particularly dangerous for critical infrastructure applications. The attack requires minimal privileges and can be executed remotely over the network, making it accessible to adversaries with basic network access. According to ATT&CK framework, this vulnerability maps to T1499.004 (Endpoint Denial of Service) and T1566.001 (Phishing via Social Engineering) as attackers could potentially use social engineering to gain initial network access before exploiting this specific vulnerability. The impact is especially severe in environments using the Industrial Internet of Things (IIoT) where these devices form part of the operational technology infrastructure.
Mitigation strategies for this vulnerability require immediate attention from industrial security teams and should include network segmentation to isolate affected devices from critical control systems. The primary remediation involves applying the vendor-provided firmware update that addresses the input validation issue within the ENIP processing logic. Organizations should implement network monitoring to detect anomalous traffic patterns that might indicate exploitation attempts, particularly focusing on unusual ENIP request structures targeting port segment functionality. Access control measures including network access control lists and firewall rules can help limit exposure by restricting network access to only authorized administrative systems. The vulnerability also highlights the importance of industrial network security monitoring and the need for security professionals to understand the specific protocols and implementation details of industrial devices. Additionally, implementing network intrusion detection systems specifically tuned to detect malformed ENIP requests can provide early warning of exploitation attempts. Regular vulnerability assessments and security audits of industrial control systems should include verification of firmware versions and patch status for all network-connected devices to prevent similar vulnerabilities from remaining unaddressed in operational environments.