CVE-2015-6307 in FirePOWER
Summary
by MITRE
Cisco FirePOWER (formerly Sourcefire) 7000 and 8000 devices with software 5.4.0.1 allow remote attackers to cause a denial of service (inspection-engine outage) via crafted packets, aka Bug ID CSCuu10871.
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Analysis
by VulDB Data Team • 01/02/2018
Cisco FirePOWER 7000 and 8000 series network security appliances running software version 5.4.0.1 contain a critical vulnerability that allows remote attackers to trigger a denial of service condition through carefully crafted packet sequences. This vulnerability specifically affects the inspection engine component responsible for deep packet inspection and threat analysis within the firewalls. The flaw manifests when the system processes malformed or specially constructed network packets that exploit a buffer handling issue in the packet processing pipeline, causing the inspection engine to become unresponsive and ultimately leading to complete service interruption. The vulnerability falls under the category of CWE-129, which represents an insufficient input validation scenario where the system fails to properly validate packet headers and content before processing them through the inspection engine. This weakness creates a direct pathway for remote attackers to disrupt network security operations without requiring authentication or privileged access, making it particularly dangerous in enterprise environments where these appliances serve as primary security gateways.
The operational impact of CVE-2015-6307 extends beyond simple service disruption to encompass complete network security compromise scenarios. When the inspection engine fails, all network traffic passing through the affected FirePOWER device becomes vulnerable to undetected threats, effectively removing the appliance from active security protection. This creates a window of opportunity for attackers to conduct further malicious activities including data exfiltration, lateral movement, or establishment of persistent access points within the network. The vulnerability's remote exploitability means that attackers can trigger the denial of service condition from anywhere on the internet without requiring physical access or network proximity to the affected devices. From an adversary perspective, this vulnerability maps directly to ATT&CK technique T1498, specifically targeting network denial of service conditions, and represents a significant operational capability for threat actors seeking to disrupt critical network infrastructure. The attack vector involves sending specially crafted packets that cause the device to enter an unrecoverable state, forcing administrators to manually restart the appliance and potentially lose security monitoring capabilities during the recovery period.
Mitigation strategies for CVE-2015-6307 should include immediate software updates to versions that address the buffer handling flaw in the inspection engine. Cisco released patches and updated firmware versions that correct the vulnerability by implementing proper input validation and buffer overflow protections within the packet processing modules. Organizations should also implement network segmentation and access controls to limit exposure of vulnerable devices to untrusted networks, while establishing monitoring protocols to detect anomalous traffic patterns that might indicate exploitation attempts. Network administrators should consider implementing redundant security appliances and failover mechanisms to maintain continuous protection even during potential exploitation events. The vulnerability highlights the importance of maintaining current security patches and implementing proper change management processes for network security infrastructure, as the flaw existed in widely deployed software versions. Additionally, organizations should conduct regular vulnerability assessments and penetration testing to identify similar weaknesses in their security infrastructure, particularly focusing on the inspection engines of network security appliances that process high volumes of traffic. The incident underscores the necessity of implementing zero-trust network architectures where even internal network segments are treated as potentially compromised, reducing the impact of such vulnerabilities on overall security posture.