CVE-2023-44195 in Junos OS Evolved
Summary
by MITRE • 10/25/2023
An Improper Restriction of Communication Channel to Intended Endpoints vulnerability in the NetworkStack agent daemon (nsagentd) of Juniper Networks Junos OS Evolved allows an unauthenticated network based attacker to cause limited impact to the availability of the system.
If specific packets reach the Routing-Engine (RE) these will be processed normally even if firewall filters are in place which should have prevented this. This can lead to a limited, increased consumption of resources resulting in a Denial-of-Service (DoS), and unauthorized access.
CVE-2023-44196 is a prerequisite for this issue.
This issue affects Juniper Networks Junos OS Evolved:
* 21.3-EVO versions prior to 21.3R3-S5-EVO; * 21.4-EVO versions prior to 21.4R3-S4-EVO; * 22.1-EVO version 22.1R1-EVO and later; * 22.2-EVO version 22.2R1-EVO and later; * 22.3-EVO versions prior to 22.3R2-S2-EVO, 22.3R3-S1-EVO; * 22.4-EVO versions prior to 22.4R3-EVO.
This issue doesn't not affected Junos OS Evolved versions prior to 21.3R1-EVO.
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Analysis
by VulDB Data Team • 10/31/2023
The vulnerability identified as CVE-2023-44195 represents a critical flaw in the NetworkStack agent daemon (nsagentd) of Juniper Networks Junos OS Evolved systems. This issue falls under the category of improper restriction of communication channels, specifically categorized as CWE-284 in the Common Weakness Enumeration framework. The vulnerability manifests when specific network packets reach the Routing-Engine (RE) component of the system, bypassing normal firewall filter mechanisms that should have prevented their processing. This represents a fundamental breakdown in the network security architecture where legitimate access controls are circumvented, allowing unauthorized packet processing that should have been blocked by existing security policies.
The technical implementation of this vulnerability stems from a failure in the nsagentd daemon's packet validation mechanisms. When packets arrive at the Routing-Engine, they are processed regardless of whether appropriate firewall filters exist to block such traffic, creating a scenario where malicious actors can exploit this weakness to consume system resources. The vulnerability requires CVE-2023-44196 to be present for exploitation, indicating a chained attack scenario where multiple vulnerabilities must be leveraged simultaneously. This chaining behavior aligns with ATT&CK technique T1210, which describes the exploitation of multiple vulnerabilities to achieve a desired outcome. The system's failure to properly enforce communication channel restrictions results in a potential resource exhaustion condition that can lead to denial-of-service scenarios.
The operational impact of this vulnerability extends beyond simple availability concerns to include potential unauthorized access capabilities. While the primary effect is limited resource consumption leading to denial-of-service conditions, the bypass of firewall filters creates a pathway for attackers to gain unauthorized access to system resources. The affected versions span multiple release lines including 21.3-EVO through 22.4-EVO, indicating this is a widespread issue affecting several major release branches. The specific version requirements show that systems running 21.3R1-EVO and earlier are not affected, suggesting the vulnerability was introduced in later releases. This vulnerability directly impacts the integrity and availability of network services, as attackers can consume system resources to the point of service disruption while potentially gaining unauthorized access to network components.
Mitigation strategies for this vulnerability should focus on immediate patch application to the affected Junos OS Evolved versions, with particular attention to the specified release versions that require updates. Organizations should implement network segmentation and additional monitoring of Routing-Engine traffic to detect anomalous packet patterns that might indicate exploitation attempts. The implementation of additional access controls and firewall rules should be considered as temporary compensating controls while patches are deployed. Security teams should monitor for unusual resource consumption patterns on affected systems and implement intrusion detection systems to identify potential exploitation attempts. The vulnerability's classification as a communication channel restriction issue means that traditional network monitoring tools may not detect the bypass of firewall filters, requiring specialized monitoring capabilities. Organizations should also consider implementing network access control lists that specifically target the packet patterns associated with this vulnerability to provide additional protection layers.