CVE-2017-3849 in IOS
Summary
by MITRE
A vulnerability in the Autonomic Networking Infrastructure (ANI) registrar feature of Cisco IOS Software (possibly 15.2 through 15.6) and Cisco IOS XE Software (possibly 3.7 through 3.18, and 16) could allow an unauthenticated, adjacent attacker to cause a denial of service (DoS) condition. The vulnerability is due to incomplete input validation on certain crafted packets. An attacker could exploit this vulnerability by sending a crafted autonomic network channel discovery packet to a device that has all the following characteristics: (1) running a Cisco IOS Software or Cisco IOS XE Software release that supports the ANI feature; (2) configured as an autonomic registrar; (3) has a whitelist configured. An exploit could allow the attacker to cause the affected device to reload. Note: Autonomic networking should be configured with a whitelist. Do not remove the whitelist as a workaround. Cisco Bug IDs: CSCvc42717.
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Analysis
by VulDB Data Team • 08/28/2024
The vulnerability identified as CVE-2017-3849 resides within the Autonomic Networking Infrastructure (ANI) registrar functionality of Cisco IOS and IOS XE software implementations. This flaw represents a critical security weakness that specifically targets the autonomic network channel discovery mechanism, affecting versions ranging from IOS 15.2 through 15.6 and IOS XE 3.7 through 3.18, along with IOS XE 16. The ANI feature was designed to enable self-management and self-configuration of network devices, but this particular vulnerability undermines that capability by introducing a denial of service condition that can be triggered without authentication.
The technical root cause of this vulnerability stems from inadequate input validation mechanisms within the ANI registrar component. When processing autonomic network channel discovery packets, the software fails to properly validate incoming data structures, creating an avenue for malformed packets to be processed without sufficient sanitization. This incomplete validation allows crafted packets to contain malicious payloads that can manipulate the device's processing logic, ultimately leading to system instability. The vulnerability specifically affects devices configured as autonomic registrars that maintain whitelist configurations, making the attack surface more defined but no less dangerous. According to the Cisco bug ID CSCvc42717, this issue manifests when the registrar processes specially crafted packets that exploit the validation gap in the packet parsing routine.
The operational impact of CVE-2017-3849 extends beyond simple service disruption to potentially compromising network infrastructure reliability and availability. An adjacent attacker with physical access or network proximity can trigger a device reload by transmitting a malformed discovery packet, effectively causing a denial of service condition that can take critical network components offline. This vulnerability is particularly concerning because it requires no authentication credentials, making it accessible to anyone within the network's physical or logical reach. The attack vector is classified as adjacent, meaning it can be executed from within the same network segment, which aligns with attack patterns described in the MITRE ATT&CK framework under the category of network infiltration and service disruption techniques. The DoS condition created by this vulnerability can result in extended network downtime, service interruption, and potential cascading failures in autonomic network environments where device reliability is paramount.
The security implications of this vulnerability are amplified by the fact that autonomic networking was specifically designed to reduce administrative overhead and enable self-managing networks, yet this flaw creates a potential point of failure that could undermine the entire autonomic architecture. Network administrators who have configured autonomic registrars with whitelist restrictions are still vulnerable to this attack, as the validation occurs at the packet processing level rather than the access control level. The recommended mitigation strategy specifically advises against removing the whitelist configuration as a workaround, which aligns with CWE-119, which describes weaknesses in memory management and input validation that can lead to buffer overflows and system instability. Organizations should implement proper patch management procedures to address this vulnerability, ensuring that all affected Cisco IOS and IOS XE devices receive the appropriate software updates that correct the input validation procedures and prevent the exploitation of this particular flaw.