CVE-2005-0598 in Content Engine
Summary
by MITRE
The RealServer RealSubscriber on Cisco devices running Application and Content Networking System (ACNS) 5.1 allow remote attackers to cause a denial of service (CPU consumption) via malformed packets.
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Analysis
by VulDB Data Team • 01/23/2025
The vulnerability identified as CVE-2005-0598 represents a significant denial of service weakness within Cisco's Application and Content Networking System version 5.1. This flaw specifically affects the RealServer RealSubscriber component which is responsible for handling real-time streaming media content. The vulnerability manifests when the system processes malformed network packets that are crafted to exploit weaknesses in the packet parsing mechanism. Such attacks can be executed remotely without requiring any authentication credentials, making them particularly dangerous as they can be initiated from anywhere on the network. The attack vector leverages the system's failure to properly validate incoming packet structures, leading to excessive cpu utilization that can eventually render the device inoperable.
The technical nature of this vulnerability stems from insufficient input validation within the RealServer RealSubscriber module. When malformed packets are received, the system fails to properly sanitize or reject these invalid inputs, causing the processor to consume excessive computational resources attempting to process the malformed data. This behavior aligns with common software security weaknesses classified under CWE-20, which addresses "Improper Input Validation" in software systems. The vulnerability specifically targets the packet processing routines that handle real-time streaming protocols, where the system's parsing logic becomes overwhelmed by malformed data structures that do not conform to expected protocol specifications. The CPU consumption spike occurs because the system's error handling mechanism becomes trapped in processing loops or recursive calls when encountering unexpected packet formats, effectively consuming all available processing capacity.
The operational impact of this vulnerability extends beyond simple service disruption as it can lead to complete system unavailability and cascading effects within network infrastructure. When a Cisco ACNS 5.1 device becomes compromised through this attack, it can no longer effectively route traffic or deliver content, potentially affecting numerous downstream services that depend on the device's functionality. Network administrators may experience significant downtime while attempting to recover from such attacks, particularly in environments where multiple devices are configured with similar vulnerable components. The vulnerability's remote execution capability means that attackers can potentially target multiple devices simultaneously, amplifying the impact of individual attacks. From an attacker's perspective, this vulnerability represents a low-effort, high-impact method for disrupting network services, aligning with techniques described in the MITRE ATT&CK framework under the T1499 category for network denial of service attacks.
Mitigation strategies for this vulnerability require immediate implementation of network segmentation and access control measures to limit exposure. Organizations should implement firewall rules that restrict access to the affected RealServer ports and consider deploying intrusion detection systems that can identify malformed packet patterns associated with this specific attack. Cisco released patches and updates to address this vulnerability, which should be applied immediately to all affected systems. Network monitoring should be enhanced to detect unusual CPU utilization patterns that may indicate exploitation attempts. Additionally, implementing rate limiting on incoming traffic and configuring proper packet filtering rules can help reduce the effectiveness of such attacks. The vulnerability serves as a reminder of the importance of robust input validation in network infrastructure components and the critical need for regular security updates in enterprise environments. Organizations should also consider implementing redundant systems to ensure service availability even when individual components are compromised by such denial of service attacks.