CVE-2014-7997 in Aironet Access Point
Summary
by MITRE
The DHCP implementation in Cisco IOS on Aironet access points does not properly handle error conditions with short leases and unsuccessful lease-renewal attempts, which allows remote attackers to cause a denial of service (device restart) by triggering a transition into a recovery state that was intended to involve a network-interface restart but actually involves a full device restart, aka Bug ID CSCtn16281.
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Analysis
by VulDB Data Team • 02/24/2022
The vulnerability described in CVE-2014-7997 represents a critical flaw in Cisco IOS implementations running on Aironet access points that manifests through improper error handling within the Dynamic Host Configuration Protocol stack. This issue specifically targets the lease management mechanism where the system fails to correctly process short lease scenarios and unsuccessful renewal attempts, creating a condition that can be exploited by remote attackers to induce a complete device restart. The flaw exists within the network infrastructure equipment that serves as a fundamental component for wireless network connectivity, making it particularly dangerous in enterprise and mission-critical environments where uninterrupted network services are essential. The vulnerability demonstrates a lack of proper state management and error recovery procedures within the IOS operating system, which is widely deployed across organizations for wireless network infrastructure.
The technical exploitation of this vulnerability occurs through a specific sequence involving DHCP lease handling that triggers an unintended transition state within the access point's network interface management system. When short leases are processed alongside failed renewal attempts, the system enters what should be a network-interface recovery state designed to restart only the interface components. However, due to the flawed implementation, this transition actually escalates to a full device restart rather than the intended partial recovery. This misbehavior stems from inadequate boundary checking and error condition management within the DHCP client implementation, where the system fails to distinguish between interface-level recovery requirements and complete system restart scenarios. The vulnerability is classified under CWE-248, which addresses "Uncaught Exception" conditions in software systems, as the error handling mechanism does not properly account for the specific conditions that lead to device restart rather than interface restart.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise network availability and business continuity in affected environments. When exploited, the vulnerability allows remote attackers to perform denial-of-service attacks against wireless access points without requiring authentication or physical access to the devices. This makes it particularly dangerous as it can be leveraged by malicious actors to create network outages that may affect thousands of users in enterprise wireless networks. The attack vector is especially concerning because it operates over the network without requiring any special privileges or credentials, making it accessible to anyone who can communicate with the affected access points. Organizations relying on these devices for wireless connectivity face significant risks including operational downtime, productivity losses, and potential security implications when network infrastructure becomes unavailable due to this vulnerability.
Mitigation strategies for CVE-2014-7997 should focus on immediate patching of affected Cisco IOS versions through official firmware updates provided by Cisco, as well as network segmentation to limit the attack surface where possible. Organizations should also implement monitoring solutions that can detect unusual restart patterns or DHCP-related anomalies that might indicate exploitation attempts. Network administrators should consider disabling unnecessary DHCP services on access points when possible and implementing robust network access control measures to prevent unauthorized network access. The vulnerability highlights the importance of proper error handling and state management in embedded systems, particularly those handling critical network infrastructure functions. This issue aligns with ATT&CK technique T1499.004 which covers "Endpoint Denial of Service" and demonstrates how seemingly minor implementation flaws in network protocols can result in significant operational impacts. Organizations should also consider implementing redundancy measures and failover mechanisms to maintain network availability during potential exploitation events. Regular vulnerability assessments and network monitoring should be conducted to identify similar issues in other network infrastructure components that may exhibit similar error handling vulnerabilities.