CVE-2016-1455 in NX-OS
Summary
by MITRE
Cisco NX-OS before 7.0(3)I2(2e) and 7.0(3)I4 before 7.0(3)I4(1) has an incorrect iptables local-interface configuration, which allows remote attackers to obtain sensitive information via TCP or UDP traffic, aka Bug ID CSCuz05365.
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Analysis
by VulDB Data Team • 09/22/2022
The vulnerability described in CVE-2016-1455 represents a critical flaw in Cisco NX-OS networking software that affects multiple software versions including those before 7.0(3)I2(2e) and 7.0(3)I4 before 7.0(3)I4(1). This issue stems from an improper configuration of iptables local-interface settings within the network operating system, creating a significant security gap that can be exploited by remote attackers to gain unauthorized access to sensitive information. The vulnerability is particularly concerning because it operates at the network layer where it can intercept and potentially exfiltrate data from TCP and UDP traffic streams without requiring authentication or privileged access. The bug ID CSCuz05365 identifies this specific weakness in the Cisco NX-OS implementation, highlighting the vendor's recognition of the severity and impact of the flawed iptables configuration. This type of vulnerability falls under the category of information disclosure flaws that can compromise the confidentiality of network communications.
The technical root cause of this vulnerability lies in the improper handling of iptables rules within the local-interface configuration of the Cisco NX-OS system. When the iptables local-interface is configured incorrectly, it fails to properly filter or validate incoming network traffic, allowing malicious actors to observe and potentially manipulate data flows. The flaw specifically impacts how the system processes TCP and UDP traffic, creating a window where sensitive information can be accessed through network packets that should normally be protected or filtered. This misconfiguration essentially creates a backdoor in the network security controls, where legitimate network traffic is not properly inspected or secured against unauthorized access. The vulnerability demonstrates a fundamental breakdown in the network security architecture, where the expected behavior of iptables rules fails to maintain proper isolation between different network segments or traffic types.
The operational impact of this vulnerability extends beyond simple information disclosure to potentially compromise the integrity and confidentiality of network communications across affected Cisco NX-OS systems. Remote attackers can exploit this weakness to gather sensitive data from network traffic without requiring physical access or elevated privileges, making the attack surface significantly larger than typical network vulnerabilities. The ability to obtain information through TCP and UDP traffic means that both structured and unstructured data flowing through the network can be intercepted, including potentially confidential business information, user credentials, or system data. This vulnerability can be particularly damaging in enterprise environments where Cisco NX-OS switches serve as critical network infrastructure components, as it allows attackers to potentially establish persistent monitoring capabilities or gather intelligence for more sophisticated attacks. The remote exploit nature of this vulnerability means that attackers can target affected systems from anywhere on the network, making it extremely difficult to contain or prevent.
Organizations affected by this vulnerability should immediately implement the vendor-provided security patches and updates to address the iptables local-interface configuration flaw. The recommended mitigation strategy involves upgrading to Cisco NX-OS versions 7.0(3)I2(2e) or later for the 7.0(3)I2 release train, and 7.0(3)I4(1) or later for the 7.0(3)I4 release train. Network administrators should also conduct comprehensive network audits to identify any systems running vulnerable software versions and ensure that all network infrastructure components are properly updated. Additional defensive measures include implementing network segmentation to limit the potential impact of exploitation, monitoring network traffic for unusual patterns that might indicate exploitation attempts, and reviewing existing iptables configurations to ensure proper filtering rules are in place. From a cybersecurity perspective, this vulnerability aligns with ATT&CK techniques related to credential access and data extraction, and organizations should consider implementing network traffic analysis tools to detect potential exploitation attempts. The vulnerability also demonstrates the importance of proper configuration management and regular security assessments to prevent similar issues from arising in network infrastructure components. This flaw serves as a reminder of the critical importance of maintaining up-to-date network security controls and the potential consequences of misconfigurations in enterprise networking equipment.