CVE-2018-0312 in FXOS
Summary
by MITRE
A vulnerability in the Cisco Fabric Services component of Cisco FXOS Software and Cisco NX-OS Software could allow an unauthenticated, remote attacker to execute arbitrary code or cause a denial of service (DoS) condition on an affected device. The vulnerability exists because the affected software insufficiently validates Cisco Fabric Services packet headers when the software processes packet data. An attacker could exploit this vulnerability by sending a maliciously crafted Cisco Fabric Services packet to an affected device. A successful exploit could allow the attacker to cause a buffer overflow condition on the device, which could allow the attacker to execute arbitrary code or cause a DoS condition on the device. This vulnerability affects the following if configured to use Cisco Fabric Services: Firepower 4100 Series Next-Generation Firewalls, Firepower 9300 Security Appliance, MDS 9000 Series Multilayer Switches, Nexus 2000 Series Fabric Extenders, Nexus 3000 Series Switches, Nexus 3500 Platform Switches, Nexus 5500 Platform Switches, Nexus 5600 Platform Switches, Nexus 6000 Series Switches, Nexus 7000 Series Switches, Nexus 7700 Series Switches, Nexus 9000 Series Switches in standalone NX-OS mode, Nexus 9500 R-Series Line Cards and Fabric Modules, UCS 6100 Series Fabric Interconnects, UCS 6200 Series Fabric Interconnects, UCS 6300 Series Fabric Interconnects. Cisco Bug IDs: CSCvd69962, CSCve02808, CSCve02810, CSCve02812, CSCve02819, CSCve02822, CSCve02831, CSCve04859.
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Analysis
by VulDB Data Team • 03/28/2023
The vulnerability described in CVE-2018-0312 represents a critical security flaw within Cisco's Fabric Services component that affects multiple network infrastructure devices. This vulnerability stems from inadequate validation of packet headers during the processing of Cisco Fabric Services data, creating a pathway for remote exploitation without authentication requirements. The flaw specifically manifests when the affected software fails to properly validate the structure and content of incoming Fabric Services packets, allowing maliciously crafted data to bypass normal security checks. This insufficient validation creates a condition where an attacker can manipulate the packet processing logic to trigger unintended behavior within the network device's operating system. The vulnerability impacts a broad range of Cisco products including Firepower appliances, MDS switches, Nexus series switches, and UCS fabric interconnects, indicating a widespread exposure across Cisco's networking portfolio. According to industry standards, this vulnerability maps to CWE-121, which describes heap-based buffer overflow conditions that occur when insufficient bounds checking is performed on buffer operations.
The technical exploitation of this vulnerability involves sending specially crafted Cisco Fabric Services packets to an affected device, which then processes these packets without proper header validation. When the device attempts to parse the malformed packet data, the insufficient validation leads to a buffer overflow condition that can be leveraged by attackers to execute arbitrary code on the target system. The buffer overflow occurs because the software allocates memory buffers based on the expected packet structure, but when malicious data exceeds these allocated boundaries, it overflows into adjacent memory regions. This overflow condition provides attackers with the opportunity to overwrite critical memory locations including return addresses, function pointers, or other control data structures. The operational impact of successful exploitation includes complete system compromise allowing attackers to execute code with the privileges of the affected service, potentially leading to persistent access or lateral movement within the network infrastructure. Additionally, attackers can trigger denial of service conditions that render network services unavailable to legitimate users, disrupting business operations and network availability.
The vulnerability affects numerous Cisco network devices that have Cisco Fabric Services configured, creating extensive exposure across enterprise and data center environments. Firepower 4100 and 9300 appliances, MDS 9000 series switches, and various Nexus series switches all present potential attack vectors for this vulnerability. The widespread impact is particularly concerning given that these devices typically operate in critical network infrastructure roles where unauthorized access could have severe consequences. The vulnerability's presence in both standalone NX-OS mode and integrated fabric modules indicates that the risk extends to both individual devices and interconnected network fabrics. Security professionals should note that the affected devices include UCS fabric interconnects which are crucial components in data center virtualization environments, making the potential attack surface even more significant. The Cisco Bug IDs associated with this vulnerability (CSCvd69962 through CSCve04859) represent multiple related issues that were addressed through various software updates and patches.
Organizations should implement immediate mitigations including applying the latest Cisco software patches and updates as released through official security advisories. Network segmentation and access control measures can help reduce the attack surface by limiting direct network access to affected devices. Monitoring network traffic for suspicious Fabric Services packet patterns can provide early detection of exploitation attempts, though this approach requires careful configuration to avoid false positives. Device configuration reviews should ensure that Fabric Services is only enabled on devices where it is absolutely required, reducing the potential exposure surface. Network administrators should also consider implementing intrusion detection systems that can identify and alert on malformed Fabric Services traffic patterns. The vulnerability's classification as a remote code execution flaw makes it particularly dangerous as attackers do not need physical access or local network credentials to exploit the vulnerability. Organizations should also conduct comprehensive vulnerability assessments to identify all affected devices within their network infrastructure, as the vulnerability affects multiple product lines and configurations. According to ATT&CK framework, this vulnerability maps to T1059 (Command and Scripting Interpreter) and T1499 (Endpoint Termination) techniques, as successful exploitation could enable command execution and system termination capabilities.