CVE-2024-30390 in Junos OS Evolved
Summary
by MITRE • 04/12/2024
An Improper Restriction of Excessive Authentication Attempts vulnerability in Juniper Networks Junos OS Evolved allows an unauthenticated, network-based attacker to cause a limited Denial of Service (DoS) to the management plane.
When an incoming connection was blocked because it exceeded the connections-per-second rate-limit, the system doesn't consider existing connections anymore for subsequent connection attempts so that the connection limit can be exceeded. This issue affects Junos OS Evolved:
All versions before 21.4R3-S4-EVO,
22.1-EVO versions before 22.1R3-S3-EVO,
22.2-EVO versions before 22.2R3-S2-EVO,
22.3-EVO versions before 22.3R2-S1-EVO, 22.3R3-EVO.
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Analysis
by VulDB Data Team • 02/07/2025
This vulnerability represents a critical flaw in Juniper Networks Junos OS Evolved that undermines the system's ability to enforce rate limiting controls for management plane connections. The issue stems from an improper restriction of excessive authentication attempts, specifically manifesting as a failure in the system's connection rate limiting mechanism. When network-based attackers attempt to overwhelm the management plane with connection requests, the system's rate limiting algorithm becomes ineffective due to a logical flaw in its connection tracking logic. The vulnerability allows an unauthenticated attacker to exploit this weakness and cause a limited denial of service condition affecting the device's management functionality.
The technical root cause lies in how the system handles connection tracking after rate limiting enforcement. When a connection attempt exceeds the configured connections-per-second threshold, the system fails to properly account for existing active connections when evaluating subsequent connection attempts. This creates a window of opportunity where attackers can bypass the intended rate limiting controls by exploiting the system's inability to maintain accurate connection state information. The flaw essentially allows the connection limit to be exceeded through careful timing and sequential connection attempts, rendering the intended security controls ineffective.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise the integrity of the device's management plane. While the DoS effect is described as "limited," the implications are significant for network security operations since management plane availability is crucial for device maintenance, monitoring, and configuration. Attackers could potentially use this vulnerability to disrupt network management functions, making it difficult for legitimate administrators to perform essential operations such as firmware updates, configuration changes, or security monitoring activities. The vulnerability affects multiple release branches of Junos OS Evolved, indicating it's a systemic issue rather than an isolated defect.
This vulnerability aligns with CWE-307, which addresses improper restriction of excessive authentication attempts, and represents a failure in the system's access control mechanisms. From an ATT&CK framework perspective, this weakness maps to T1499.004 - Endpoint Denial of Service, and potentially T1566.001 - Phishing, as attackers might leverage the DoS condition to create opportunities for additional attacks. The vulnerability's network-based nature means it can be exploited remotely without requiring authentication, making it particularly dangerous in environments where management planes are accessible from untrusted networks. Organizations should prioritize patching affected systems as this flaw could be exploited to create conditions that facilitate more sophisticated attacks against the device's management interface.
The affected versions span multiple release cycles, indicating this is not a recent introduction but rather a persistent issue that has affected various iterations of the Junos OS Evolved platform. This widespread impact suggests that the underlying design flaw has remained unaddressed across multiple development cycles, highlighting potential gaps in the security testing and validation processes for rate limiting controls. The vulnerability's presence in both major release branches (21.x, 22.x) and their respective service packs demonstrates the need for comprehensive security reviews of connection management and rate limiting mechanisms. Organizations should implement immediate mitigation measures including network segmentation, firewall rules to limit management plane access, and monitoring for unusual connection patterns that might indicate exploitation attempts.