CVE-2016-6391 in IOS
Summary
by MITRE
Cisco IOS 12.2 and 15.0 through 15.3 allows remote attackers to cause a denial of service (traffic-processing outage) via a crafted series of Common Industrial Protocol (CIP) requests, aka Bug ID CSCur69036.
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Analysis
by VulDB Data Team • 09/24/2024
Cisco IOS devices running versions 12.2 and 15.0 through 15.3 contain a vulnerability that enables remote attackers to trigger a denial of service condition through carefully constructed Common Industrial Protocol requests. This vulnerability represents a critical flaw in the network infrastructure software that governs industrial control systems and manufacturing environments. The flaw specifically affects the processing of CIP traffic which is fundamental to industrial automation protocols used extensively in manufacturing and process control environments. The vulnerability manifests when the system receives a malformed sequence of CIP requests that causes the device to enter a state where it can no longer properly process network traffic, resulting in complete service disruption.
The technical root cause of this vulnerability lies in insufficient input validation within the IOS CIP processing module. When the system receives a specially crafted series of CIP messages, the parsing logic fails to properly handle certain edge cases in the protocol structure, leading to memory corruption or resource exhaustion. This type of vulnerability falls under CWE-129, which encompasses issues related to insufficient input validation, and specifically relates to improper handling of protocol messages in network infrastructure devices. The vulnerability demonstrates characteristics of a buffer over-read condition where the system attempts to process data beyond its allocated memory boundaries, causing unpredictable behavior and system instability.
The operational impact of this vulnerability extends far beyond typical network service disruptions as it affects industrial control systems that are critical to manufacturing processes, power generation, and other industrial operations. When exploited, the vulnerability can cause complete traffic processing outages on affected Cisco IOS devices, potentially leading to production halts, safety system failures, and significant financial losses. The attack vector is particularly concerning because it requires no authentication and can be executed from remote locations, making it an attractive target for both nation-state actors and criminal organizations targeting critical infrastructure. This vulnerability aligns with ATT&CK technique T1498, which describes denial of service attacks that target network infrastructure, and represents a significant risk to industrial cybersecurity posture.
Organizations affected by this vulnerability should immediately implement mitigation strategies including network segmentation to isolate critical industrial systems, deploying intrusion detection systems to monitor for suspicious CIP traffic patterns, and applying the latest security patches provided by Cisco. The recommended approach involves configuring access control lists to filter CIP traffic at network boundaries and implementing redundant network paths to ensure continued operation during potential exploitation attempts. System administrators should also consider disabling unnecessary CIP processing capabilities on devices that do not require industrial protocol support. This vulnerability underscores the importance of maintaining up-to-date security patches for industrial control systems and highlights the need for comprehensive vulnerability management programs that address both traditional IT and operational technology environments. The incident also demonstrates the critical nature of securing industrial protocols like CIP that are increasingly connected to enterprise networks, making proper security controls essential for protecting against sophisticated attacks targeting critical infrastructure components.