CVE-2017-12235 in IOS
Summary
by MITRE
A vulnerability in the implementation of the PROFINET Discovery and Configuration Protocol (PN-DCP) for Cisco IOS 12.2 through 15.6 could allow an unauthenticated, remote attacker to cause an affected device to reload, resulting in a denial of service (DoS) condition. The vulnerability is due to the improper parsing of ingress PN-DCP Identify Request packets destined to an affected device. An attacker could exploit this vulnerability by sending a crafted PN-DCP Identify Request packet to an affected device and then continuing to send normal PN-DCP Identify Request packets to the device. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a DoS condition. This vulnerability affects Cisco devices that are configured to process PROFINET messages. Beginning with Cisco IOS Software Release 12.2(52)SE, PROFINET is enabled by default on all the base switch module and expansion-unit Ethernet ports. Cisco Bug IDs: CSCuz47179.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 09/09/2024
The vulnerability identified as CVE-2017-12235 represents a critical denial of service flaw within Cisco IOS implementations that affects versions ranging from 12.2 through 15.6. This issue specifically targets the PROFINET Discovery and Configuration Protocol (PN-DCP) component, which is integral to industrial automation networks where Cisco devices serve as communication endpoints. The flaw manifests in the improper parsing of ingress PN-DCP Identify Request packets, creating a condition where maliciously crafted packets can trigger unexpected behavior in the affected network infrastructure. The vulnerability's exploitation requires minimal privileges as it does not require authentication, making it particularly dangerous in industrial environments where network availability is paramount for operational continuity.
The technical root cause of this vulnerability stems from inadequate input validation within the PN-DCP processing logic of Cisco IOS. When the system receives a malformed PN-DCP Identify Request packet, the parsing routine fails to properly handle the unexpected data structure, leading to memory corruption or execution flow disruption. This parsing failure results in a system crash that manifests as an automatic device reload, effectively rendering the network device unavailable to legitimate users. The vulnerability operates at the network protocol level, specifically targeting the application layer processing of industrial communication protocols, and demonstrates how legacy protocol implementations can contain fundamental parsing flaws that persist across multiple software releases.
The operational impact of this vulnerability extends beyond simple service disruption as it can severely compromise industrial control systems that rely on continuous network availability. In manufacturing environments, process control systems, supervisory control and data acquisition networks, and other critical infrastructure components may experience significant downtime when affected devices reload. The vulnerability's exploitation pattern requires only a single initial crafted packet followed by continued normal packet traffic, making it difficult to detect and mitigate in real-time network monitoring systems. This characteristic aligns with attack patterns classified under the MITRE ATT&CK framework's T1499.004 technique for network denial of service, where attackers leverage protocol implementation weaknesses to cause system instability.
Cisco's vulnerability assessment identified this issue as affecting devices with PROFINET enabled, which became default in IOS Release 12.2(52)SE across all base switch modules and expansion-unit Ethernet ports. The default enablement of PROFINET functionality increases the attack surface significantly, as many devices in industrial environments may not be properly secured or monitored for such protocol-specific attacks. The vulnerability's presence in multiple IOS versions indicates a systemic flaw in protocol implementation that required patching across an extended software lifecycle. Organizations implementing industrial network security measures should consider this vulnerability when assessing their operational technology security posture, particularly in environments where network reliability directly impacts production processes.
Mitigation strategies for this vulnerability encompass both immediate patch deployment and network segmentation approaches. Cisco released software updates addressing the parsing issue in affected IOS versions, requiring administrators to upgrade their devices to patched software releases. Network administrators should also implement access control measures to limit exposure of affected devices to untrusted networks, particularly by disabling PROFINET processing on devices not requiring industrial protocol support. The implementation of intrusion detection systems capable of identifying anomalous PN-DCP traffic patterns can provide early warning of potential exploitation attempts. Additionally, network segmentation strategies that isolate industrial control systems from general enterprise networks can limit the impact of successful exploitation attempts, aligning with industry best practices for operational technology security as recommended in NIST SP 800-84 and IEC 62443 standards.