CVE-2024-20304 Overview
A memory exhaustion vulnerability exists in the multicast traceroute version 2 (Mtrace2) feature of Cisco IOS XR Software that could allow an unauthenticated, remote attacker to exhaust the UDP packet memory of an affected device. This vulnerability exists because the Mtrace2 code does not properly handle packet memory, allowing an attacker to send crafted packets that exhaust incoming UDP packet memory and prevent the device from processing higher-level UDP-based protocol packets.
Critical Impact
Successful exploitation allows remote attackers to cause a denial of service (DoS) condition by exhausting UDP packet memory, disrupting network services that depend on UDP-based protocols. This vulnerability can be exploited using either IPv4 or IPv6.
Affected Products
- Cisco IOS XR 7.7.x (versions 7.7.1, 7.7.2, 7.7.21)
- Cisco IOS XR 7.8.x (versions 7.8.1, 7.8.2, 7.8.12, 7.8.22)
- Cisco IOS XR 7.9.x (versions 7.9.1, 7.9.2, 7.9.21)
- Cisco IOS XR 7.10.x (versions 7.10.1, 7.10.2)
- Cisco IOS XR 7.11.x (versions 7.11.1, 7.11.2)
- Cisco IOS XR 24.1.x (versions 24.1.1, 24.1.2)
- Cisco IOS XR 24.2.x (versions 24.2.1, 24.2.11)
Discovery Timeline
- 2024-09-11 - CVE-2024-20304 published to NVD
- 2024-10-03 - Last updated in NVD database
Technical Details for CVE-2024-20304
Vulnerability Analysis
This vulnerability is classified as CWE-401 (Missing Release of Memory after Effective Lifetime), commonly referred to as a memory leak. The Mtrace2 feature in Cisco IOS XR Software fails to properly release packet memory after processing, leading to a resource exhaustion condition when handling specially crafted network packets.
The vulnerability allows unauthenticated remote attackers to target the UDP packet memory pool of affected devices. When exploited, the device becomes unable to process legitimate UDP-based protocol traffic, which can severely impact network operations that rely on protocols such as SNMP, DNS, NTP, and other UDP-based services running on the affected router.
Root Cause
The root cause of CVE-2024-20304 lies in improper memory management within the Mtrace2 code implementation. Specifically, the code fails to properly release allocated packet memory buffers after they have been used for processing Mtrace2 requests. This missing deallocation causes memory to accumulate over time as crafted packets are received, eventually exhausting the available UDP packet memory pool.
Attack Vector
The attack can be executed remotely over the network without requiring any authentication or user interaction. An attacker sends specially crafted packets to the Mtrace2 feature on an affected Cisco IOS XR device. These packets trigger the memory handling flaw, causing memory to be allocated but never released. By continuously sending malicious packets, an attacker can exhaust the incoming UDP packet memory, leading to denial of service.
The vulnerability is exploitable via both IPv4 and IPv6, expanding the potential attack surface for organizations running dual-stack network configurations.
Detection Methods for CVE-2024-20304
Indicators of Compromise
- Unusual increase in memory utilization on Cisco IOS XR devices, particularly in UDP packet memory pools
- Degradation or failure of UDP-based services such as SNMP, DNS forwarding, or NTP synchronization
- High volume of malformed or suspicious Mtrace2 packets observed in network traffic captures
- System logs indicating memory exhaustion warnings or UDP processing errors
Detection Strategies
- Monitor Cisco IOS XR memory utilization metrics with focus on UDP packet memory allocation patterns
- Implement network traffic analysis to detect anomalous Mtrace2 traffic patterns or unusually high volumes of multicast traceroute requests
- Configure SNMP traps to alert on memory threshold breaches on affected devices
- Deploy intrusion detection signatures to identify crafted Mtrace2 packets targeting this vulnerability
Monitoring Recommendations
- Establish baseline memory utilization patterns for affected Cisco IOS XR devices to detect anomalous consumption
- Enable syslog forwarding to a centralized SIEM for correlation of memory-related events across network infrastructure
- Implement NetFlow or similar flow analysis to track Mtrace2 traffic volumes and identify potential attack patterns
- Schedule regular health checks that include UDP packet memory pool status on all affected devices
How to Mitigate CVE-2024-20304
Immediate Actions Required
- Review the Cisco Security Advisory for affected version details and available patches
- Inventory all Cisco IOS XR devices running vulnerable versions (7.7.x through 7.11.x and 24.1.x through 24.2.x)
- Apply vendor-provided patches as soon as they become available for your specific IOS XR release
- Implement network access controls to limit exposure of affected devices to untrusted networks
Patch Information
Cisco has published a security advisory addressing this vulnerability. Organizations should consult the Cisco Security Advisory cisco-sa-pak-mem-exhst-3ke9FeFy for specific patch versions and upgrade paths for their deployed IOS XR releases. The advisory provides detailed information on fixed software releases for each affected version.
Workarounds
- Implement access control lists (ACLs) to restrict Mtrace2 traffic to trusted sources only
- Consider disabling the Mtrace2 feature if it is not required for network operations, pending patch deployment
- Segment network infrastructure to limit attacker access to management interfaces of affected devices
- Deploy rate limiting on interfaces exposed to untrusted networks to reduce the impact of potential exploitation attempts
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
