CVE-2008-3810 in IOS
Summary
by MITRE
Cisco IOS 12.2 and 12.4, when NAT Skinny Call Control Protocol (SCCP) Fragmentation Support is enabled, allows remote attackers to cause a denial of service (device reload) via segmented SCCP messages, aka CSCsg22426, a different vulnerability than CVE-2008-3811.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 08/17/2019
Cisco IOS devices running versions 12.2 and 12.4 are vulnerable to a denial of service condition when NAT Skinny Call Control Protocol SCCP fragmentation support is enabled. This vulnerability specifically targets the handling of segmented SCCP messages that occur during network address translation operations. The flaw exists in how the IOS processing engine manages fragmented SCCP packets, particularly when these packets are received through NAT environments where message segmentation occurs. When an attacker crafts and sends specifically formatted SCCP messages that trigger fragmentation within the NAT path, the IOS device becomes unable to properly reconstruct and process these fragmented packets, leading to an immediate device reload and complete service disruption.
The technical mechanism behind this vulnerability involves the improper handling of packet fragmentation within the SCCP protocol stack of Cisco IOS. When SCCP messages are fragmented due to NAT operations, the device's processing logic fails to correctly reassemble these fragments or properly handle the fragmentation state transitions. This issue falls under CWE-129 Input Validation, specifically related to improper handling of fragmented network protocol data. The vulnerability is particularly dangerous because it operates at the network protocol level within the IOS kernel, making it difficult to detect through standard application-level monitoring. The attack requires minimal privileges and can be executed remotely, making it highly exploitable in network environments where NAT is commonly deployed for voice traffic management.
The operational impact of this vulnerability extends beyond simple service disruption to encompass complete network availability compromise for voice services. Organizations relying on Cisco IOS devices for voice communication infrastructure face significant risk when this vulnerability is exploited, as the device reload causes immediate loss of all active voice calls and prevents new call setup until manual intervention occurs. The vulnerability affects enterprise and service provider networks where SCCP-based IP phone systems are deployed, particularly in environments using NAT for voice traffic management. This creates a cascading effect where multiple devices may experience simultaneous reloads if attackers target the NAT gateway, potentially affecting entire voice communication networks within an organization. The vulnerability also demonstrates the inherent risks of complex protocol handling within network operating systems, where edge cases in packet processing can lead to complete system failure.
Mitigation strategies for this vulnerability require immediate implementation of several defensive measures. Network administrators should disable SCCP fragmentation support when NAT is in use, which can be accomplished through specific IOS configuration commands that prevent the device from processing fragmented SCCP messages. Additionally, implementing network segmentation to isolate voice traffic from general network traffic can reduce the attack surface. The Cisco IOS software should be updated to versions that address this specific vulnerability, as the company released patches to correct the packet reassembly logic. Network monitoring should be enhanced to detect unusual patterns in SCCP traffic that might indicate exploitation attempts, and access controls should be implemented to limit who can send SCCP messages to affected devices. Organizations should also consider implementing intrusion detection systems that can identify and alert on known exploitation patterns for this vulnerability, aligning with ATT&CK technique T1499.002 for network denial of service attacks. The vulnerability underscores the importance of proper protocol implementation testing and the need for robust input validation mechanisms in network operating system components.