CVE-2015-0643 in IOS
Summary
by MITRE
Cisco IOS 12.2, 12.4, 15.0, 15.1, 15.2, 15.3, and 15.4 and IOS XE 2.5.x, 2.6.x, 3.1.xS through 3.12.xS before 3.12.3S, 3.2.xE through 3.7.xE before 3.7.1E, 3.3.xSG, 3.4.xSG, and 3.13.xS before 3.13.2S allow remote attackers to cause a denial of service (memory consumption and device reload) by sending malformed IKEv2 packets over (1) IPv4 or (2) IPv6, aka Bug ID CSCuo75572.
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Analysis
by VulDB Data Team • 04/16/2022
Cisco IOS and IOS XE software versions affected by CVE-2015-0643 contain a critical memory handling vulnerability within the Internet Key Exchange version 2 protocol implementation that enables remote attackers to trigger denial of service conditions through carefully crafted malformed packets. This vulnerability specifically affects the IKEv2 protocol processing logic where the system fails to properly validate incoming packet structures, leading to excessive memory consumption and eventual device reloads. The flaw exists in the way the software handles malformed IKEv2 messages sent over both IPv4 and IPv6 networks, making it particularly dangerous as it can be exploited from any network location where the vulnerable device is accessible.
The technical root cause of this vulnerability stems from insufficient input validation within the IKEv2 packet processing module, which falls under CWE-129 Input Validation and CWE-20 Improper Input Validation. When the system receives malformed IKEv2 packets, the parsing routine does not properly sanitize or reject invalid packet structures, causing the memory allocation routines to consume excessive resources in attempting to process these malformed messages. The vulnerability manifests as a memory leak or memory exhaustion condition that gradually consumes available system memory until the device becomes unstable and requires a complete reload to recover. This behavior aligns with ATT&CK technique T1499.004 Network Denial of Service, where adversaries exploit weaknesses in network protocols to disrupt service availability.
The operational impact of this vulnerability is severe for organizations relying on Cisco networking equipment, as it can be exploited remotely without authentication, making it particularly dangerous for devices exposed to untrusted networks or the internet. Network administrators may experience unexpected device reboots, service interruptions, and potential loss of network connectivity during attack periods. The vulnerability affects multiple software versions across different IOS and IOS XE release lines, indicating a widespread issue that requires coordinated patching across various network infrastructure components. Organizations with devices running affected versions may face significant operational disruption if not addressed promptly, as the denial of service condition can persist until the device is manually rebooted or the vulnerable software is updated.
Mitigation strategies should focus on immediate patching of affected devices to the latest software releases that contain the necessary fixes for the IKEv2 processing logic. Network administrators should also implement access control measures to restrict exposure of vulnerable devices to untrusted networks, particularly by blocking IKEv2 traffic at network boundaries when possible. Additional protective measures include implementing network monitoring to detect unusual packet patterns that may indicate exploitation attempts, configuring logging to capture IKEv2 packet processing events, and establishing incident response procedures for handling potential denial of service events. The vulnerability demonstrates the importance of proper input validation in network protocol implementations and highlights the need for continuous security assessment of network infrastructure components to prevent similar issues from arising in future releases.