CVE-2015-0659 in IOS
Summary
by MITRE
The Autonomic Networking Infrastructure (ANI) implementation in Cisco IOS allows remote attackers to trigger self-referential adjacencies via a crafted Autonomic Networking (AN) message, aka Bug ID CSCup62157.
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Analysis
by VulDB Data Team • 06/22/2017
The vulnerability described in CVE-2015-0659 represents a critical flaw within Cisco IOS's Autonomic Networking Infrastructure implementation that enables remote attackers to manipulate network adjacency relationships through crafted AN messages. This issue specifically affects the autonomic networking capabilities that Cisco designed to enable self-configuring and self-managing network segments without manual intervention. The vulnerability stems from insufficient validation of incoming autonomic networking messages, allowing malicious actors to construct specially formatted packets that can cause the affected device to establish incorrect adjacency relationships with itself, creating what are known as self-referential adjacencies. Such behavior fundamentally compromises the network's ability to maintain proper routing and forwarding decisions, potentially leading to complete network disruption or unauthorized access to network resources.
The technical exploitation of this vulnerability occurs through the manipulation of the autonomic networking protocol implementation within Cisco IOS devices. When a device receives a crafted AN message that triggers the self-referential adjacency condition, it essentially creates a loop in its adjacency database where the device believes it has a direct connection to itself. This condition can be leveraged to cause routing instability, packet forwarding failures, or even complete service outages within the autonomic network segment. The flaw exists in the message processing logic where the system fails to properly validate the source and destination addresses in autonomic networking messages, allowing crafted inputs to bypass normal adjacency establishment procedures. According to CWE classification, this vulnerability maps to CWE-224 which deals with insufficient validation of the source of autonomic networking messages, and CWE-347 which addresses improper validation of the authenticity of autonomic networking messages.
The operational impact of this vulnerability extends beyond simple network disruption to potentially enable more sophisticated attacks within the compromised network environment. When self-referential adjacencies are established, the affected device may begin routing traffic in unexpected patterns, potentially creating denial of service conditions or allowing unauthorized access to network segments. Network administrators may find their autonomic network segments becoming unstable, with routing tables continuously fluctuating and network performance degrading significantly. The vulnerability is particularly dangerous because it operates at the network infrastructure level, potentially affecting large portions of network topology when exploited. From an ATT&CK framework perspective, this vulnerability aligns with techniques involving network denial of service and network configuration modification, potentially enabling adversaries to establish persistent network access points or disrupt critical network services.
Mitigation strategies for CVE-2015-0659 should focus on immediate patch deployment from Cisco, as the vendor released specific software updates addressing the flawed message validation logic. Network administrators should disable autonomic networking features on affected devices until patches are applied, particularly in environments where network segmentation is critical. Implementing network monitoring solutions that can detect anomalous adjacency patterns or self-referential relationships can provide early warning of exploitation attempts. Additionally, access controls should be tightened around autonomic networking message handling, ensuring that only trusted sources can communicate within autonomic network segments. The vulnerability highlights the importance of validating all network protocol inputs and demonstrates the risks associated with implementing complex network automation features without adequate security controls. Organizations should also consider implementing network segmentation strategies that isolate autonomic network components from critical infrastructure to limit the potential impact of such vulnerabilities.