CVE-2024-30389 in Junos OS
Summary
by MITRE • 04/12/2024
An Incorrect Behavior Order vulnerability in the Packet Forwarding Engine (PFE) of Juniper Networks Junos OS on EX4300 Series allows an unauthenticated, network-based attacker to cause an integrity impact to networks downstream of the vulnerable device.
When an output firewall filter is applied to an interface it doesn't recognize matching packets but permits any traffic. This issue affects Junos OS 21.4 releases from 21.4R1 earlier than 21.4R3-S6. This issue does not affect Junos OS releases earlier than 21.4R1.
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Analysis
by VulDB Data Team • 02/07/2025
The vulnerability identified as CVE-2024-30389 represents a critical Incorrect Behavior Order flaw within the Packet Forwarding Engine of Juniper Networks Junos OS operating on EX4300 Series devices. This vulnerability stems from a fundamental mismanagement of packet processing logic where the system fails to properly evaluate and handle traffic matching specific criteria. The flaw manifests when output firewall filters are configured on network interfaces, creating a scenario where packets that should be recognized and processed according to defined rules are instead ignored or mishandled. This misbehavior directly impacts the integrity of network traffic flow and can compromise the security posture of affected networks.
From a technical perspective, the vulnerability operates within the PFE component which is responsible for high-speed packet forwarding and filtering operations. The issue occurs specifically when output firewall filters are applied to interfaces, causing the system to incorrectly process matching packets. The system fails to properly identify packets that match the defined filter criteria, yet paradoxically permits traffic that should be restricted or filtered out. This behavior creates a situation where network administrators believe their security policies are properly enforced, while in reality the filtering mechanism is bypassed for certain traffic patterns. The vulnerability is particularly concerning as it affects the fundamental packet processing capabilities of the device, potentially allowing malicious traffic to traverse networks without proper filtering or monitoring.
The operational impact of this vulnerability extends beyond simple traffic bypassing to potentially compromise network integrity and security. An unauthenticated, network-based attacker can exploit this weakness to cause downstream network integrity issues, potentially allowing unauthorized access to network segments that should be protected by firewall policies. This vulnerability affects Junos OS 21.4 releases from 21.4R1 through 21.4R3-S6, meaning that organizations running these specific software versions are at risk. The vulnerability does not affect earlier releases, indicating that it was introduced in a specific code modification or release cycle. This impacts network infrastructure that relies on EX4300 Series switches for traffic management and security enforcement, potentially creating blind spots in network monitoring and control.
Organizations affected by this vulnerability should immediately consider implementing mitigations such as upgrading to Junos OS releases that contain the appropriate patches and fixes. The vulnerability aligns with CWE-254, which addresses security weaknesses related to improper behavior order in software systems, and could be categorized under ATT&CK technique T1562.007 for "Tunneling via Network Device" as it may enable unauthorized traffic traversal. Network administrators should also consider implementing additional monitoring and detection measures to identify anomalous traffic patterns that might indicate exploitation attempts. The vulnerability demonstrates the critical importance of proper packet processing logic in network security devices and underscores the need for comprehensive testing of security features before deployment. Organizations should also review their existing firewall policies to ensure they are not relying on the vulnerable behavior and should implement alternative security controls where necessary.
This vulnerability exemplifies the complexity of modern network security systems where a single flaw in packet processing can have cascading effects on network integrity and security posture. The issue highlights the need for continuous security assessment and the importance of maintaining up-to-date firmware on network infrastructure components. The fact that this affects a specific range of releases suggests that the vulnerability may have been introduced through a targeted code change or feature implementation that was not properly validated for security implications. Network security teams should prioritize this vulnerability in their risk assessment processes and ensure that all affected devices are patched or otherwise secured according to vendor recommendations and industry best practices for maintaining network integrity and preventing unauthorized access to downstream network segments.