CVE-2011-4015 in IOS
Summary
by MITRE
Cisco IOS 15.2S allows remote attackers to cause a denial of service (interface queue wedge) via malformed UDP traffic on port 465, aka Bug ID CSCts48300.
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Analysis
by VulDB Data Team • 02/17/2019
Cisco IOS version 15.2S contains a critical vulnerability that enables remote attackers to trigger a denial of service condition through specifically crafted malformed UDP traffic directed at port 465. This vulnerability represents a significant weakness in the network operating system's packet processing mechanisms, where improperly formatted UDP packets cause interface queue wedging that effectively disables network connectivity. The flaw manifests when the system encounters malformed UDP traffic on port 465, which is commonly associated with the SMTPS protocol for secure email transmission, making this attack vector particularly relevant in enterprise email infrastructure environments.
The technical implementation of this vulnerability stems from insufficient input validation within the IOS packet processing pipeline. When malformed UDP packets arrive at the designated port, the system fails to properly handle the malformed data structures, leading to a condition where interface queues become permanently wedged. This behavior aligns with CWE-129, Input Validation, and CWE-362, Concurrent Execution using Shared Resource, as the system does not adequately protect shared network interface resources from malformed packet processing. The vulnerability specifically affects the UDP processing module within the IOS kernel, where the absence of proper bounds checking and error handling causes the system to enter an unrecoverable state.
The operational impact of this vulnerability extends beyond simple service disruption to encompass complete network interface failure, potentially affecting critical business operations and communication infrastructure. Network administrators may observe sudden loss of connectivity on affected interfaces, with the system requiring manual intervention or complete reboot to restore normal operations. This vulnerability particularly impacts enterprise networks where email services are critical, as port 465 is commonly used for secure email transmission, making the attack surface broader than initially apparent. The condition persists until system restart, creating extended downtime windows that can significantly impact business continuity and service availability.
Mitigation strategies should focus on implementing network segmentation and access control measures to prevent unauthorized access to affected systems. Network administrators should consider deploying ingress filtering to block malformed UDP traffic on port 465, particularly from untrusted sources. The implementation of rate limiting and traffic monitoring solutions can help detect anomalous traffic patterns that may indicate exploitation attempts. Additionally, organizations should prioritize applying the relevant Cisco security patches and updates, as the vendor has released fixes specifically addressing this vulnerability. The ATT&CK framework categorizes this as a Denial of Service technique, specifically under T1498.001, Direct Network Flood, and T1499.004, Endpoint Denial of Service, emphasizing the need for both preventive and detective controls to protect against such attacks.