CVE-2013-2779 in Asr 1023 Router
Summary
by MITRE
Cisco IOS XE 3.4 before 3.4.5S, and 3.5 through 3.7 before 3.7.1S, on 1000 series Aggregation Services Routers (ASR) does not properly implement the Cisco Multicast Leaf Recycle Elimination (MLRE) feature, which allows remote attackers to cause a denial of service (card reload) via fragmented IPv6 MVPN (aka MVPNv6) packets, aka Bug ID CSCub34945, a different vulnerability than CVE-2013-1164.
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Analysis
by VulDB Data Team • 01/02/2022
The vulnerability described in CVE-2013-2779 affects Cisco IOS XE software versions prior to specific patch releases on Cisco 1000 series Aggregation Services Routers. This issue specifically targets the implementation of the Cisco Multicast Leaf Recycle Elimination (MLRE) feature, which is designed to optimize multicast traffic handling in network environments. The flaw manifests when processing fragmented IPv6 MVPN packets, creating a condition where legitimate network traffic can be exploited to trigger system instability. This vulnerability represents a significant concern for network infrastructure as it enables remote attackers to induce system-wide disruptions through carefully crafted malicious packets that exploit the multicast handling mechanisms within the router's software implementation.
The technical flaw stems from improper handling of fragmented IPv6 MVPN packets within the MLRE feature implementation. When these specific packet types are processed by affected Cisco IOS XE versions, the system fails to properly validate or handle the fragmentation state of the multicast packets, leading to memory corruption or resource exhaustion conditions. The vulnerability operates at the network protocol level where the router's multicast processing engine encounters malformed or unexpected packet sequences that cause the system to enter an unstable state requiring manual intervention. This particular implementation weakness allows attackers to send specially crafted fragmented packets that trigger the router's multicast processing logic in a way that results in complete system reload or card restart operations. The vulnerability is categorized under CWE-121, which deals with stack-based buffer overflow conditions, and represents a denial of service scenario that affects the availability of network services.
The operational impact of this vulnerability extends beyond simple network disruption as it can result in complete service outages across affected network segments. When triggered, the vulnerability forces the affected router cards to reload, causing temporary loss of network connectivity for all services passing through those devices. Network administrators may experience significant downtime as the system requires manual intervention to restore normal operations, potentially affecting critical business processes and network availability. The remote nature of the attack means that adversaries can exploit this vulnerability from outside the network perimeter without requiring physical access or authentication credentials, making it particularly dangerous for organizations relying on these routers for critical infrastructure connectivity. This vulnerability directly impacts the availability aspect of the CIA triad and can be classified under ATT&CK technique T1498, which involves network denial of service attacks.
Mitigation strategies for this vulnerability involve immediate deployment of Cisco's recommended security patches and software updates that address the specific MLRE implementation flaw. Network administrators should prioritize updating affected Cisco 1000 series ASR routers to versions 3.4.5S or later, or 3.7.1S or later, depending on the specific software version in use. Additionally, implementing network segmentation and access control measures can help limit the potential impact of exploitation attempts, while monitoring for unusual multicast traffic patterns may aid in early detection of attempted attacks. Organizations should also consider disabling multicast functionality on affected devices if the feature is not critical for their operations, though this may impact legitimate multicast services. The vulnerability highlights the importance of maintaining up-to-date network device firmware and implementing comprehensive vulnerability management processes to prevent exploitation of known security flaws in critical network infrastructure components.