CVE-2013-2784 in Nano-10 PLC
Summary
by MITRE
Triangle Research International (aka Tri) Nano-10 PLC devices with firmware before r81 use an incorrect algorithm for bounds checking of data in Modbus/TCP packets, which allows remote attackers to cause a denial of service (networking outage) via a crafted packet to TCP port 502.
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Analysis
by VulDB Data Team • 07/22/2024
The vulnerability identified as CVE-2013-2784 affects Triangle Research International's Nano-10 Programmable Logic Controller devices running firmware versions prior to r81. These industrial control devices operate within critical infrastructure environments where network availability and system stability are paramount. The affected devices implement Modbus/TCP protocol for communication, which is widely used in industrial automation systems and follows the standard port 502 for Modbus communication. The flaw resides in the device's implementation of bounds checking mechanisms within the Modbus/TCP packet processing logic, creating a condition where malformed or specially crafted packets can trigger unexpected behavior in the device's network stack.
The technical flaw represents a classic buffer overflow vulnerability stemming from improper input validation within the Modbus protocol handler. When the Nano-10 PLC receives a Modbus/TCP packet with malformed data structures or incorrect length indicators, the device's bounds checking algorithm fails to properly validate the packet boundaries. This incorrect algorithm allows attackers to craft packets that appear legitimate but contain data that exceeds expected buffer limits or violates expected data formats. The vulnerability specifically targets the data field validation process within Modbus requests, where the device fails to properly check array bounds before processing received data. This weakness aligns with CWE-129, which describes improper validation of array indices, and CWE-787, which addresses out-of-bounds write operations. The implementation error occurs at the network protocol layer where the device's Modbus/TCP parser does not adequately protect against malformed packet structures that could cause memory corruption or resource exhaustion.
The operational impact of this vulnerability extends beyond simple denial of service to potentially compromise entire industrial control networks. Remote attackers can exploit this vulnerability without requiring authentication or physical access to the device, making it particularly dangerous in operational technology environments. When successfully exploited, the crafted Modbus/TCP packet causes the device to crash or become unresponsive, leading to network outages that can disrupt industrial processes. The denial of service affects not only the individual device but can also cascade through the control system, potentially causing wider operational disruptions in manufacturing, power generation, or other critical infrastructure sectors. This vulnerability directly impacts the availability and reliability of industrial control systems, as outlined in the NIST Cybersecurity Framework's availability core function. The attack vector through TCP port 502 means that any network-accessible device running the vulnerable firmware becomes a potential target, increasing the attack surface significantly in industrial environments where such devices are often exposed to untrusted networks.
Mitigation strategies for this vulnerability require immediate firmware updates from Triangle Research International to address the bounds checking algorithm implementation. Organizations should implement network segmentation to isolate critical PLC devices from general network access, particularly blocking direct access to TCP port 502 from untrusted networks. Network access control lists and firewalls should be configured to restrict Modbus/TCP traffic to only authorized systems and personnel. Additionally, network monitoring should be enhanced to detect unusual Modbus/TCP packet patterns that may indicate exploitation attempts. The vulnerability demonstrates the importance of secure coding practices in industrial control systems and aligns with ATT&CK technique T1499, which covers network disruption attacks. Organizations should also consider implementing intrusion detection systems specifically tuned to detect Modbus protocol anomalies and maintain comprehensive network monitoring to identify potential exploitation attempts. Regular vulnerability assessments and security audits of industrial control systems are essential to identify similar implementation flaws in other devices within the operational technology environment.