CVE-2015-0636 in IOS
Summary
by MITRE
The Autonomic Networking Infrastructure (ANI) implementation in Cisco IOS 12.2, 12.4, 15.0, 15.2, 15.3, and 15.4 and IOS XE 3.10.xS through 3.13.xS before 3.13.1S allows remote attackers to cause a denial of service (disrupted domain access) via spoofed AN messages that reset a finite state machine, aka Bug ID CSCup62293.
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Analysis
by VulDB Data Team • 04/16/2022
The vulnerability described in CVE-2015-0636 represents a critical flaw within Cisco's Autonomic Networking Infrastructure implementation that affects multiple versions of IOS and IOS XE software. This issue specifically targets the ANI protocol's handling of authentication and state management mechanisms, creating a pathway for remote attackers to disrupt network operations through carefully crafted spoofed messages. The vulnerability manifests in the form of manipulated AN messages that trigger unexpected behavior in the finite state machine responsible for maintaining autonomic network domain integrity. This particular flaw falls under the category of improper handling of authenticated network messages, which aligns with CWE-284 access control weaknesses and represents a significant threat to network availability and operational continuity.
The technical implementation of this vulnerability stems from insufficient validation of incoming AN messages within the ANI subsystem of Cisco IOS devices. When legitimate AN messages are spoofed or manipulated by unauthorized parties, they cause the finite state machine to reset unexpectedly, leading to a complete disruption of the autonomic domain's operational state. This reset effectively terminates the domain's ability to maintain its self-managing network characteristics, resulting in a denial of service condition that impacts the entire network segment under the affected device's control. The flaw operates at the protocol level where the system fails to properly validate message authenticity and integrity before processing state transitions, creating an exploitable condition that requires minimal privileges to exploit. The vulnerability demonstrates a classic case of inadequate input validation and state management, where the system does not properly account for malformed or maliciously crafted messages that could originate from unauthenticated sources.
The operational impact of this vulnerability extends far beyond simple network disruption, as it fundamentally compromises the autonomic networking capabilities that organizations rely upon for automated network management and self-healing operations. When exploited, the vulnerability can cause complete loss of domain access, forcing network administrators to manually intervene in network operations that were designed to be self-managing and resilient. This disruption affects not only the immediate device but also the broader network domain that depends on the autonomic infrastructure for maintaining consistent network behavior and connectivity. The vulnerability particularly impacts enterprise and service provider networks that utilize Cisco's autonomic networking features, potentially causing cascading failures throughout the network infrastructure. Organizations may experience extended downtime while restoring normal network operations, as the finite state machine reset requires manual intervention to re-establish proper domain state and re-enable autonomic functionality. The attack vector allows for remote exploitation without requiring authentication credentials, making it particularly dangerous in environments where network devices are exposed to untrusted network segments.
Mitigation strategies for this vulnerability require immediate software updates and patches from Cisco, specifically targeting the affected IOS and IOS XE versions that contain the flawed ANI implementation. Network administrators should prioritize applying the relevant security patches that address the finite state machine reset vulnerability in the ANI protocol processing. Additional defensive measures include implementing network segmentation to limit exposure of autonomic network components to untrusted networks, deploying intrusion detection systems to monitor for suspicious AN message patterns, and establishing network access controls that restrict the sources of AN messages. The implementation of proper message authentication and integrity checking mechanisms should be considered as temporary compensating controls while awaiting official patches. Organizations should also review their network design to minimize the attack surface of autonomic networking features and ensure that network devices are properly configured to validate message authenticity before processing autonomic network operations. This vulnerability highlights the importance of maintaining up-to-date network security implementations and demonstrates the critical need for proper protocol validation and state management in network infrastructure components. The issue represents a significant concern for organizations that depend on autonomic networking capabilities, as it undermines the fundamental security assumptions of self-managing network systems and creates opportunities for attackers to disrupt critical network operations.