CVE-2011-0943 in IOS XR
Summary
by MITRE
Cisco IOS XR 3.8.3, 3.8.4, and 3.9.1 allows remote attackers to cause a denial of service (NetIO process restart or device reload) via a crafted IPv4 packet, aka Bug ID CSCth44147.
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Analysis
by VulDB Data Team • 03/23/2017
Cisco IOS XR software versions 3.8.3, 3.8.4, and 3.9.1 contain a critical vulnerability that enables remote attackers to execute denial of service attacks through carefully constructed IPv4 packets. This vulnerability specifically targets the NetIO process within the operating system, causing it to restart or triggering a complete device reload. The flaw arises from insufficient input validation when processing malformed IPv4 packets, allowing malicious actors to exploit the system's handling of network traffic. The vulnerability is categorized under CWE-129 as an improper input validation issue, where the system fails to properly validate the boundaries of input data before processing. This weakness directly enables an attacker to manipulate the device's network processing capabilities and disrupt normal operations. The impact of this vulnerability extends beyond simple service interruption as it can lead to complete system unavailability, affecting network infrastructure reliability and business continuity. The attack vector is particularly concerning as it requires no authentication or privileged access, making it accessible to any remote attacker capable of sending crafted packets to the affected device. This vulnerability aligns with ATT&CK technique T1498 which describes the use of network denial of service attacks to disrupt system availability. The NetIO process restart or device reload behavior creates a cascading effect that can impact routing protocols, network services, and overall network stability. The vulnerability affects Cisco IOS XR platforms that are commonly deployed in service provider environments, where uptime and reliability are critical for maintaining network services. The flaw represents a fundamental weakness in the software's packet processing logic, where malformed IPv4 packet headers or payload structures can trigger unexpected behavior in the network input/output subsystem. Organizations running these affected versions should prioritize immediate patching or implementation of network segmentation measures to prevent exploitation. The vulnerability demonstrates the importance of robust input validation in network operating systems, particularly in environments where devices must process untrusted network traffic from multiple sources. Security professionals should monitor for potential exploitation attempts and implement appropriate network monitoring to detect anomalous packet patterns that could indicate exploitation of this vulnerability. The remediation approach typically involves applying Cisco's security patches or upgrading to unaffected software versions that contain proper input validation mechanisms for IPv4 packet processing.