CVE-2020-3230 in IOS
Summary
by MITRE
A vulnerability in the Internet Key Exchange Version 2 (IKEv2) implementation in Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to prevent IKEv2 from establishing new security associations. The vulnerability is due to incorrect handling of crafted IKEv2 SA-Init packets. An attacker could exploit this vulnerability by sending crafted IKEv2 SA-Init packets to the affected device. An exploit could allow the attacker to cause the affected device to reach the maximum incoming negotiation limits and prevent further IKEv2 security associations from being formed.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 10/21/2020
The vulnerability identified as CVE-2020-3230 represents a critical weakness in the Internet Key Exchange Version 2 protocol implementation within Cisco IOS and IOS XE software platforms. This flaw specifically targets the IKEv2 security association negotiation process, creating a denial-of-service condition that can severely impact network security infrastructure. The vulnerability stems from improper packet handling mechanisms within the IKEv2 implementation, particularly when processing SA-Init messages that are sent during the initial phase of security association establishment. This weakness affects a broad range of Cisco networking equipment including routers and switches that utilize the affected software versions, making it a significant concern for enterprise and service provider networks that rely heavily on IKEv2 for secure communications.
The technical exploitation of CVE-2020-3230 occurs when an unauthenticated remote attacker crafts and transmits specially formatted IKEv2 SA-Init packets to the targeted device. These malicious packets are designed to trigger a specific code path within the IKEv2 processing logic that fails to properly validate incoming negotiation requests. The vulnerability is classified as a CWE-129 weakness, representing an improper input validation issue that allows crafted inputs to disrupt normal system operations. According to ATT&CK framework, this vulnerability maps to T1499.004 - Endpoint Denial of Service, where an attacker can specifically target network infrastructure to create service disruption. The implementation flaw causes the affected device to increment its internal counters for incoming negotiations beyond acceptable limits, effectively exhausting the system's capacity to establish new security associations. This behavior creates a cascading effect where legitimate users attempting to establish secure connections encounter failures, while the device remains in a degraded state unable to process new IKEv2 negotiations.
The operational impact of this vulnerability extends beyond simple service disruption, as it can compromise the overall security posture of affected networks. When an attacker successfully exploits CVE-2020-3230, they can effectively disable the IKEv2 functionality on the targeted device, preventing legitimate remote access and site-to-site VPN connections from being established. This disruption affects critical network services that depend on IKEv2 for secure communication, including remote worker access, branch office connectivity, and secure management sessions. The vulnerability is particularly dangerous because it requires no authentication to exploit, making it accessible to any remote attacker with network access to the targeted device. The device's inability to establish new security associations creates a persistent denial-of-service condition that can last until manual intervention occurs, including device restarts or configuration changes that reset the negotiation counters. This vulnerability directly impacts the availability aspect of the CIA triad, as it compromises the ability of legitimate users to access network resources through secure channels.
Organizations affected by CVE-2020-3230 should implement immediate mitigations to protect their network infrastructure from exploitation. The primary recommended approach involves applying the latest security patches provided by Cisco, which include fixes to the IKEv2 processing logic that prevent the incorrect handling of crafted SA-Init packets. Network administrators should also consider implementing access control measures such as firewall rules that restrict IKEv2 traffic to trusted sources only, although this approach provides only partial protection since the vulnerability can be exploited from any network location. Additionally, monitoring systems should be configured to detect unusual patterns in IKEv2 negotiation attempts, which could indicate exploitation attempts. Cisco recommends implementing rate limiting on IKEv2 negotiation requests and configuring the device to reset negotiation counters more aggressively to prevent exhaustion of available resources. The vulnerability also highlights the importance of maintaining up-to-date security configurations and conducting regular vulnerability assessments to identify and remediate similar weaknesses in network infrastructure components. Organizations should also review their incident response procedures to ensure they can quickly detect and respond to exploitation attempts targeting IKEv2 implementations.