CVE-2014-3330 in NX-OS
Summary
by MITRE
Cisco NX-OS 6.1(2)I2(1) on Nexus 9000 switches does not properly process packet-drop policy checks for logged packets, which allows remote attackers to bypass intended access restrictions via a flood of packets matching a policy that contains the log keyword, aka Bug ID CSCuo02489.
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Analysis
by VulDB Data Team • 02/10/2022
The vulnerability identified as CVE-2014-3330 affects Cisco NX-OS software version 6.1(2)I2(1) running on Nexus 9000 series switches, representing a critical flaw in the packet processing and access control mechanisms of these network devices. This issue stems from improper handling of packet-drop policy checks specifically for logged packets within the switch's security framework. The vulnerability is particularly concerning because it enables remote attackers to circumvent intended access restrictions through a targeted packet flooding attack that exploits the logging mechanism within the packet filtering policies.
The technical flaw manifests in the way the switch processes packets that match policies containing the log keyword. When a packet matches a policy rule that includes logging, the system should properly evaluate whether the packet should be dropped according to the policy configuration. However, the vulnerability causes the switch to fail to properly execute the packet-drop checks for these logged packets, creating a scenario where malicious actors can flood the system with packets matching specific policies that include the log directive. This failure in policy enforcement allows the attacker to bypass the intended access restrictions that should normally prevent unauthorized packet processing or forwarding.
The operational impact of this vulnerability extends beyond simple access bypass, as it can lead to significant security implications for network infrastructure. Network administrators may experience unexpected packet drops or forwarding behavior that could disrupt legitimate traffic patterns while simultaneously allowing unauthorized access to network resources. The vulnerability creates a condition where an attacker can effectively overwhelm the logging system with legitimate-looking packets that should be dropped but are instead allowed to pass through the security controls. This could potentially enable further attacks or provide attackers with additional network visibility and access that they would not normally have.
The attack vector for this vulnerability requires remote access to the network infrastructure and the ability to send packets to the affected switch that match specific policy rules containing the log keyword. Attackers can exploit this by flooding the switch with packets that match policies designed to log and drop traffic, but due to the flawed processing, the drop mechanism fails for logged packets. This creates a scenario where the logging functionality becomes a bypass mechanism rather than a security control, allowing attackers to flood the network while maintaining access to the system. The vulnerability is particularly dangerous in environments where packet logging is used as part of security monitoring and access control policies.
Security professionals should implement immediate mitigations including updating to patched versions of Cisco NX-OS software, reviewing and modifying packet filtering policies to remove or modify the log keyword in potentially vulnerable rules, and implementing additional monitoring for unusual packet flooding patterns. The vulnerability aligns with CWE-284 Access Control Issues, specifically concerning improper access control enforcement in network security policies, and can be categorized under ATT&CK technique T1071.004 Application Layer Protocol: DNS where attackers may use network flooding techniques to exploit policy processing flaws. Organizations should also consider implementing network segmentation and additional access controls to limit the impact of potential exploitation, while monitoring for abnormal packet processing behavior that could indicate exploitation attempts.