CVE-2011-3347 in Red Hat
Summary
by MITRE
A certain Red Hat patch to the be2net implementation in the kernel package before 2.6.32-218.el6 on Red Hat Enterprise Linux (RHEL) 6, when promiscuous mode is enabled, allows remote attackers to cause a denial of service (system crash) via non-member VLAN packets.
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Analysis
by VulDB Data Team • 01/03/2022
The vulnerability identified as CVE-2011-3347 represents a critical denial of service flaw within the kernel's be2net network driver implementation on Red Hat Enterprise Linux 6 systems. This issue specifically affects systems running kernel versions prior to 2.6.32-218.el6 where the be2net driver is utilized for Broadcom network adapters. The vulnerability manifests when the network interface is configured in promiscuous mode, a mode commonly used for network monitoring and analysis operations. Promiscuous mode allows network interfaces to capture all packets traversing the network segment, regardless of their destination address, making it a valuable tool for network administrators and security professionals. However, this functionality introduces security considerations that must be carefully managed.
The technical flaw stems from improper handling of VLAN packets when the network interface operates in promiscuous mode. When non-member VLAN packets are received by the system, the be2net driver fails to properly validate or process these packets, leading to a kernel panic and subsequent system crash. This occurs because the driver does not adequately check the VLAN membership status of incoming packets before attempting to process them, creating a condition where malicious actors can exploit this gap in validation logic. The vulnerability specifically targets the interaction between the VLAN tagging mechanism and the promiscuous mode functionality, where the driver's packet processing routine does not account for packets that should not be processed under the current interface configuration. This represents a classic buffer over-read or improper input validation issue that can be classified under CWE-129, which deals with insufficient validation of the length of input data.
The operational impact of this vulnerability extends beyond simple system downtime, as it can be exploited remotely by attackers without requiring authentication or elevated privileges. An attacker positioned on the same network segment can simply send specially crafted VLAN packets to trigger the system crash, effectively causing a denial of service against the targeted system. This makes the vulnerability particularly dangerous in shared network environments where attackers may not have direct access to the target system but can still influence network traffic. The vulnerability affects systems running Red Hat Enterprise Linux 6, which was widely deployed in enterprise environments, meaning that organizations with legacy systems could be at risk. The impact is significant because network infrastructure components often serve as critical system components, and their availability directly affects business operations and service delivery. In enterprise environments where network monitoring is critical, the vulnerability could be exploited to disrupt monitoring capabilities or cause cascading failures when multiple systems are affected.
Mitigation strategies for this vulnerability involve applying the appropriate kernel security patches provided by Red Hat, specifically updating to kernel version 2.6.32-218.el6 or later. Organizations should prioritize patching systems running affected kernel versions, particularly those with network interfaces configured in promiscuous mode. Alternative mitigation approaches include disabling promiscuous mode on network interfaces when it is not actively needed, implementing network segmentation to limit the scope of potential attacks, and monitoring for unusual VLAN packet traffic patterns that might indicate exploitation attempts. Network administrators should also consider implementing intrusion detection systems that can identify and alert on suspicious VLAN packet behaviors. The vulnerability highlights the importance of proper input validation in kernel drivers and demonstrates how seemingly benign network functionality can create security risks when not properly implemented. From an ATT&CK framework perspective, this vulnerability aligns with techniques involving privilege escalation and denial of service, as it allows an attacker to cause system instability without requiring elevated privileges. Organizations should also review their network security policies to ensure that promiscuous mode usage is properly monitored and restricted to authorized personnel only. The vulnerability underscores the critical need for comprehensive security testing of kernel modules and network drivers, particularly those handling complex network protocols like VLAN tagging and packet filtering operations.