CVE-2015-6369 in Firepower Extensible Operating System
Summary
by MITRE
The USB driver in Cisco Firepower Extensible Operating System 1.1(1.160) on Firepower 9000 devices allows physically proximate attackers to cause a denial of service via a crafted USB device that triggers invalid USB commands, aka Bug ID CSCux10531.
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Analysis
by VulDB Data Team • 04/18/2018
The vulnerability identified as CVE-2015-6369 affects the USB driver component within Cisco Firepower Extensible Operating System version 1.1(1.160) running on Firepower 9000 security appliances. This represents a significant security weakness that exploits the device's physical proximity requirements to execute a denial of service attack. The vulnerability specifically targets the USB driver functionality that processes incoming USB commands from connected devices, creating a pathway for malicious actors to disrupt normal system operations through carefully crafted USB hardware inputs.
The technical flaw stems from inadequate input validation within the USB driver implementation, which fails to properly sanitize or verify USB commands received from attached devices. When a maliciously constructed USB device connects to the Firepower 9000 appliance, it can send invalid or malformed USB commands that the driver cannot properly handle. This lack of proper command validation and error handling causes the system to become unresponsive or crash entirely, resulting in a denial of service condition that can persist until manual intervention or system reboot occurs. The vulnerability operates at the kernel level within the operating system's USB subsystem, making it particularly dangerous as it can compromise the entire device's operational capabilities.
From an operational perspective, this vulnerability presents a serious risk to network security infrastructure since Firepower 9000 devices serve as critical security appliances that protect enterprise networks from various threats. An attacker who can physically access the device can exploit this vulnerability to disrupt network security operations, potentially creating windows of opportunity for more sophisticated attacks. The requirement for physical proximity limits the attack surface but does not eliminate the risk, as unauthorized personnel with access to the device location could exploit this weakness. The impact extends beyond simple service disruption since network security appliances are often mission-critical components that maintain continuous network monitoring and protection functions.
This vulnerability aligns with CWE-121, which addresses buffer overflow conditions in kernel-mode drivers, and represents a classic example of insufficient input validation in system-level components. The attack vector falls under the ATT&CK technique T1210 - Exploitation of Remote Services, though with the specific constraint of physical access requirements. The lack of proper USB command validation creates a condition where malicious input can cause system instability, potentially leading to complete device compromise. Organizations should consider this vulnerability as part of a broader security posture assessment, particularly when evaluating physical security controls around critical network infrastructure devices.
Mitigation strategies should include immediate deployment of Cisco's security patches and updates that address the USB driver validation issues. Network administrators should also implement strict physical access controls to prevent unauthorized personnel from connecting potentially malicious USB devices to Firepower 9000 appliances. Additional protective measures include disabling unnecessary USB ports when not required for operational purposes, implementing USB device whitelisting policies, and monitoring for unusual USB connection events. Regular vulnerability assessments and security audits should be conducted to identify similar weaknesses in other system components. Organizations should also maintain detailed incident response procedures that account for potential denial of service scenarios affecting critical security infrastructure, ensuring rapid recovery and minimal impact on network security operations.