CVE-2016-8209 in NetIron
Summary
by MITRE
Improper checks for unusual or exceptional conditions in Brocade NetIron 05.8.00 and later releases up to and including 06.1.00, when the Management Module is continuously scanned on port 22, may allow attackers to cause a denial of service (crash and reload) of the management module.
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Analysis
by VulDB Data Team • 12/22/2020
The vulnerability identified as CVE-2016-8209 represents a critical flaw in Brocade NetIron network infrastructure devices that affects firmware versions 05.8.00 through 06.1.00. This issue manifests as an improper handling of exceptional conditions within the Management Module's SSH service implementation. The vulnerability specifically arises when the management module undergoes continuous scanning on port 22, which is the standard Secure Shell protocol port used for remote administration and management of network devices. The flaw demonstrates characteristics consistent with CWE-254, which addresses security weaknesses related to improper checks for unusual or exceptional conditions, making it particularly dangerous in network security contexts where management availability is paramount.
The technical exploitation of this vulnerability occurs through sustained scanning activities targeting the SSH management interface, which triggers a cascade of exceptional conditions that the management module cannot properly handle. When attackers continuously probe the management module's SSH service on port 22, the system fails to properly validate or limit the incoming connections or malformed requests, leading to an unhandled exception that ultimately causes the management module to crash and subsequently reload. This behavior directly aligns with the ATT&CK framework's T1499.004 technique for network denial of service attacks, specifically targeting network infrastructure components. The vulnerability demonstrates a fundamental flaw in input validation and exception handling mechanisms within the management module's SSH daemon implementation.
The operational impact of CVE-2016-8209 extends beyond simple service disruption to create significant reliability concerns for network administrators. When the management module crashes and reloads, network operators lose access to critical management functions for the affected device, potentially rendering the network element effectively inaccessible for troubleshooting, configuration changes, or monitoring activities. This denial of service condition can be particularly devastating in enterprise environments where network availability is critical for business operations, as administrators may be unable to perform essential maintenance or respond to network incidents. The vulnerability's potential for remote exploitation means that attackers can trigger this condition without physical access to the device, making it a serious concern for network security posture. The issue also demonstrates how seemingly benign scanning activities can be weaponized to create operational disruptions that align with ATT&CK's T1566.001 technique for initial access through spearphishing attachments or links, though in this case the attack vector is more focused on service disruption rather than data exfiltration.
Organizations affected by this vulnerability should implement immediate mitigations including network segmentation to isolate management interfaces, implementing access control lists to limit SSH access to trusted networks only, and deploying intrusion detection systems to monitor for unusual scanning patterns targeting port 22. The most effective long-term solution involves upgrading to firmware versions that address this vulnerability, as Brocade has released patches to resolve the improper exception handling and validation issues within the management module's SSH service implementation. Security teams should also consider implementing monitoring solutions that can detect management module instability or frequent restarts as potential indicators of exploitation attempts. The vulnerability highlights the importance of proper exception handling in network infrastructure software and demonstrates how inadequate input validation can create denial of service conditions that significantly impact operational availability. Organizations should also review their network scanning practices to ensure that routine security assessments do not inadvertently trigger these types of vulnerabilities, particularly when conducting port scans against management interfaces.