CVE-2018-0006 in Junos
Summary
by MITRE
A high rate of VLAN authentication attempts sent from an adjacent host on the local broadcast domain can trigger high memory utilization by the BBE subscriber management daemon (bbe-smgd), and lead to a denial of service condition. The issue was caused by attempting to process an unbounded number of pending VLAN authentication requests, leading to excessive memory allocation. This issue only affects devices configured for DHCPv4/v6 over AE auto-sensed VLANs, utilized in Broadband Edge (BBE) deployments. Other configurations are unaffected by this issue. Affected releases are Juniper Networks Junos OS: 15.1 versions prior to 15.1R6-S2, 15.1R7; 16.1 versions prior to 16.1R5-S1, 16.1R6; 16.2 versions prior to 16.2R2-S2, 16.2R3; 17.1 versions prior to 17.1R2-S5, 17.1R3; 17.2 versions prior to 17.2R2.
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Analysis
by VulDB Data Team • 01/20/2023
This vulnerability represents a denial of service condition affecting Juniper Networks Broadband Edge (BBE) deployments through improper handling of VLAN authentication requests within the BBE subscriber management daemon. The issue manifests when an adjacent host on the local broadcast domain sends a high volume of VLAN authentication attempts, causing the bbe-smgd process to consume excessive memory resources. The root cause lies in the daemon's inability to properly manage an unbounded number of pending VLAN authentication requests, resulting in continuous memory allocation without adequate bounds checking or request queuing mechanisms. This represents a classic resource exhaustion vulnerability where the system's memory management becomes overwhelmed by the volume of incoming authentication requests.
The technical flaw specifically impacts devices configured for DHCPv4/v6 over AE auto-sensed VLANs, which are commonly deployed in broadband edge environments where subscriber management and VLAN assignment occur dynamically. The vulnerability operates at the network infrastructure level, affecting the subscriber management daemon that handles authentication requests from subscribers connecting through auto-sensed VLANs. This configuration pattern is particularly susceptible because the daemon must process each authentication request in real-time while maintaining state information for each pending request, creating a memory leak scenario when the request rate exceeds normal operational thresholds. The issue demonstrates poor input validation and resource management practices, where the system fails to implement rate limiting or queue depth controls for authentication requests.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise the entire broadband edge infrastructure. When the BBE subscriber management daemon consumes excessive memory resources, it can cause the device to become unresponsive or crash entirely, leading to widespread service outages for subscribers connected through affected VLANs. Network operators deploying BBE solutions in production environments face significant risk of service degradation or complete denial of service when malicious or misconfigured hosts attempt to flood the system with authentication requests. The vulnerability affects multiple Junos OS versions across different release branches, indicating a systemic issue in the memory management and request handling code that spans several major releases.
Mitigation strategies should focus on implementing rate limiting controls and memory allocation bounds within the BBE subscriber management daemon. Network administrators should upgrade to patched versions of Junos OS that contain fixes for this vulnerability, specifically targeting the affected release versions mentioned in the advisory. The recommended approach involves applying the vendor-provided security patches that address the unbounded memory allocation issue through proper request queue management and authentication rate limiting. Additionally, network segmentation and access control measures can be implemented to restrict the sources of VLAN authentication requests, preventing adjacent hosts from overwhelming the system. From a compliance perspective, this vulnerability aligns with CWE-770, which addresses allocation of resources without proper limits or bounds, and maps to ATT&CK technique T1499.004 for network denial of service attacks targeting infrastructure components. Organizations should also implement monitoring solutions to detect unusual authentication request patterns that could indicate exploitation attempts, providing early warning capabilities for potential attacks against the BBE subscriber management system.