CVE-2015-0672 in IOS XR
Summary
by MITRE
The DHCPv4 server in Cisco IOS XR 5.2.2 on ASR 9000 devices allows remote attackers to cause a denial of service (service outage) via a flood of crafted DHCP packets, aka Bug ID CSCup67822.
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Analysis
by VulDB Data Team • 05/01/2022
The vulnerability identified as CVE-2015-0672 represents a critical denial of service weakness in Cisco IOS XR 5.2.2 software running on ASR 9000 series devices. This flaw specifically affects the DHCPv4 server implementation within the routing platform, creating a pathway for remote attackers to disrupt network operations through carefully constructed DHCP packet flooding attacks. The issue manifests as a service outage condition that can severely impact network availability and operational continuity for organizations relying on these enterprise-grade routing devices.
The technical root cause of this vulnerability lies in insufficient input validation and packet processing logic within the DHCP server component of the IOS XR operating system. When the ASR 9000 device receives a high volume of malformed or specially crafted DHCP packets, the system fails to properly handle the incoming traffic, leading to resource exhaustion and subsequent service disruption. This weakness falls under the category of inadequate input validation as classified by CWE-20, where the system does not adequately sanitize or validate incoming network packets before processing them. The vulnerability demonstrates a classic example of resource exhaustion attack patterns that can be categorized under ATT&CK technique T1499.002 for network denial of service.
The operational impact of this vulnerability extends beyond simple service interruption, as it can affect critical network infrastructure components that form the backbone of enterprise communications. Organizations utilizing ASR 9000 devices in their network infrastructure face potential disruption of network services, including routing stability and connectivity for downstream network segments. The remote exploitability of this vulnerability means that attackers can initiate attacks from outside the network perimeter, making it particularly dangerous for organizations with exposed network services. This weakness directly impacts the availability aspect of the CIA triad, potentially causing cascading failures in network operations that depend on stable routing functionality.
Mitigation strategies for CVE-2015-0672 should prioritize immediate software updates and patches provided by Cisco to address the specific DHCP server processing flaw. Network administrators should implement rate limiting and access control mechanisms to reduce the impact of potential attack traffic while awaiting official patches. The implementation of network segmentation and firewall rules can help limit exposure of vulnerable devices to untrusted networks. Additionally, monitoring systems should be enhanced to detect unusual DHCP traffic patterns that may indicate an ongoing attack. Organizations should also consider implementing intrusion detection systems specifically configured to identify and alert on malformed DHCP packet sequences. The vulnerability highlights the importance of maintaining up-to-date network device firmware and following security advisories from vendors. Cisco released security patches addressing this specific issue, and organizations should prioritize deployment of these updates to prevent exploitation. The incident also underscores the need for comprehensive network security monitoring and incident response procedures to quickly identify and respond to similar vulnerabilities in network infrastructure devices.