CVE-2018-0241 in IOX XR
Summary
by MITRE
A vulnerability in the UDP broadcast forwarding function of Cisco IOS XR Software could allow an unauthenticated, adjacent attacker to cause a denial of service (DoS) condition on the affected device. The vulnerability is due to improper handling of UDP broadcast packets that are forwarded to an IPv4 helper address. An attacker could exploit this vulnerability by sending multiple UDP broadcast packets to the affected device. An exploit could allow the attacker to cause a buffer leak on the affected device, eventually resulting in a DoS condition requiring manual intervention to recover. This vulnerability affects all Cisco IOS XR platforms running 6.3.1, 6.2.3, or earlier releases of Cisco IOS XR Software when at least one IPv4 helper address is configured on an interface of the device. Cisco Bug IDs: CSCvi35625.
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Analysis
by VulDB Data Team • 03/03/2023
The vulnerability described in CVE-2018-0241 represents a critical denial of service weakness within Cisco IOS XR Software that specifically targets the UDP broadcast forwarding mechanism. This flaw exists in the handling of network traffic when devices are configured with IPv4 helper addresses, creating a pathway for malicious actors to disrupt normal operations. The vulnerability affects Cisco IOS XR versions 6.3.1, 6.2.3, and earlier releases, making it particularly concerning given the widespread deployment of these software versions across network infrastructure. The issue manifests when the system processes UDP broadcast packets that are destined for IPv4 helper addresses, exposing a fundamental flaw in packet processing logic that was not adequately addressed in the software implementation.
The technical root cause of this vulnerability lies in the improper handling of buffer management during UDP broadcast packet processing. When an attacker sends multiple UDP broadcast packets to an affected device, the system's failure to properly manage memory allocation and deallocation leads to progressive buffer leakage. This memory management failure creates a condition where available system resources gradually diminish, eventually leading to complete system exhaustion and subsequent denial of service. The vulnerability is classified as an adjacent attack vector, meaning that exploitation requires physical or network proximity to the target device, but does not require authentication credentials. The specific Cisco Bug ID CSCvi35625 documents this issue within the company's internal tracking systems, highlighting the recognized nature of the problem within the vendor's own development lifecycle.
The operational impact of this vulnerability extends beyond simple service disruption, as it requires manual intervention for system recovery, creating significant operational overhead for network administrators. The DoS condition resulting from buffer leakage can persist until system resources are manually restored through device reboot or other administrative procedures, potentially causing extended network downtime. Organizations relying on Cisco IOS XR for critical network infrastructure face substantial risk from this vulnerability, particularly in environments where network availability is paramount. The attack vector's adjacency requirement somewhat limits the scope of potential exploitation compared to remote vulnerabilities, but the ease of execution and severe impact make it a significant concern for network security teams.
Mitigation strategies for this vulnerability should prioritize immediate software updates to versions that address the buffer handling flaw, with particular attention to the specific Cisco IOS XR releases mentioned in the vulnerability description. Network segmentation and access controls can help reduce the attack surface by limiting physical or network proximity to affected devices. Implementing network monitoring solutions that can detect unusual UDP broadcast traffic patterns may provide early warning of attempted exploitation. The vulnerability aligns with CWE-129, which covers improper validation of input boundaries, and relates to ATT&CK technique T1499.002 for network denial of service attacks. Organizations should also consider implementing rate limiting mechanisms on interfaces configured with IPv4 helper addresses to reduce the impact of potential exploitation attempts. Regular security assessments and vulnerability scanning should be conducted to identify other potentially affected systems within the network infrastructure.