CVE-2008-3806 in IOS
Summary
by MITRE
Cisco IOS 12.0 through 12.4 on Cisco 10000, uBR10012 and uBR7200 series devices handles external UDP packets that are sent to 127.0.0.0/8 addresses intended for IPC communication within the device, which allows remote attackers to cause a denial of service (device or linecard reload) via crafted UDP packets, a different vulnerability than CVE-2008-3805.
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Analysis
by VulDB Data Team • 08/02/2021
Cisco IOS versions 12.0 through 12.4 running on Cisco 10000 series, uBR10012, and uBR7200 series routers contain a critical vulnerability in their handling of internal IPC communication protocols. The flaw exists when these devices process external UDP packets destined for the 127.0.0.0/8 address space, which is reserved for loopback communication and internal device processes. This vulnerability represents a classic case of improper input validation where the router fails to properly filter or reject packets that should only be processed internally, allowing external attackers to craft malicious UDP packets that exploit this communication channel. The vulnerability operates at the network protocol level and specifically targets the router's internal IPC mechanisms, making it particularly dangerous as it can be exploited from outside the network perimeter without requiring authentication or privileged access. According to CWE-20, this represents a weakness in input validation where the system fails to properly validate the source or destination of network packets, allowing unauthorized manipulation of internal processes. The attack vector is remote and requires no special privileges, making it highly accessible to threat actors. When exploited, the vulnerability triggers a denial of service condition that can cause complete device reload or linecard restart, effectively disrupting network services and potentially creating cascading failures in network infrastructure. The impact extends beyond simple service interruption as these devices often serve as critical network infrastructure components where downtime can affect large portions of network traffic. This vulnerability is distinct from CVE-2008-3805, indicating separate code paths or mechanisms within the IOS implementation that both lead to similar denial of service outcomes but through different attack vectors. The security implications align with ATT&CK technique T1499.004 which covers network denial of service attacks targeting network infrastructure devices. Organizations running affected Cisco IOS versions should prioritize patching or implementing network segmentation to isolate these devices from untrusted networks. The vulnerability demonstrates a fundamental flaw in the router's packet processing architecture where internal communication channels are not properly isolated from external network traffic, creating an attack surface that should remain restricted to internal device processes only. Network administrators should also consider implementing ingress filtering to block traffic destined for the 127.0.0.0/8 address space from external sources, as this addresses the root cause of the vulnerability by preventing the malicious packets from reaching the vulnerable code path in the first place. The exploitability of this vulnerability is high due to the nature of UDP protocols and the fact that the attack can be executed without any authentication requirements, making it a prime target for automated exploitation tools in network scanning campaigns.