CVE-2022-22196 in Junos OS
Summary
by MITRE • 04/14/2022
An Improper Check for Unusual or Exceptional Conditions vulnerability in the Routing Protocol Daemon (rpd) of Juniper Networks Junos OS and Junos OS Evolved allows an adjacent, unauthenticated attacker with an established ISIS adjacency to cause a Denial of Service (DoS). The rpd CPU spikes to 100% after a malformed ISIS TLV has been received which will lead to processing issues of routing updates and in turn traffic impact. This issue affects: Juniper Networks Junos OS 19.3 versions prior to 19.3R3-S4; 19.4 versions prior to 19.4R2-S6, 19.4R3-S6; 20.1 versions prior to 20.1R3-S2; 20.2 versions prior to 20.2R3-S3; 20.3 versions prior to 20.3R3-S1; 20.4 versions prior to 20.4R3; 21.1 versions prior to 21.1R3; 21.2 versions prior to 21.2R2. Juniper Networks Junos OS Evolved All versions prior to 20.4R3-S3-EVO; 21.2 versions prior to 21.2R2-EVO. This issue does not affect Juniper Networks Junos OS versions prior to 19.3R1.
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Analysis
by VulDB Data Team • 04/20/2022
The vulnerability identified as CVE-2022-22196 represents a critical improper check for unusual or exceptional conditions within the Routing Protocol Daemon (rpd) of Juniper Networks Junos OS and Junos OS Evolved platforms. This weakness manifests as a denial of service condition that can be triggered by an adjacent, unauthenticated attacker who has already established an ISIS adjacency with the affected device. The vulnerability operates through a specific flaw in how the rpd processes incoming ISIS TLV (Type-Length-Value) structures, which are fundamental components of the Intermediate System to Intermediate System (ISIS) routing protocol used for network communication and route dissemination.
The technical implementation of this vulnerability involves the rpd daemon's failure to properly validate and handle malformed ISIS TLV data structures. When such malformed data is received through an established ISIS adjacency, the routing protocol daemon experiences a significant CPU spike reaching 100% utilization. This excessive resource consumption occurs because the daemon enters an infinite processing loop or encounters a condition that causes it to repeatedly attempt to parse or handle the malformed TLV data. The resulting system overload prevents the daemon from processing legitimate routing updates and maintaining normal network operations, effectively creating a denial of service condition that impacts the entire routing function of the device.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise network stability and availability. Network administrators may experience complete routing table processing failures, leading to traffic black holes where packets cannot be properly routed through the affected device. The CPU exhaustion issue can cascade into broader system performance degradation, affecting other services running on the same platform. This vulnerability is particularly concerning because it requires only an adjacent network presence and does not necessitate authentication credentials, making it accessible to attackers within the same broadcast domain. The issue affects a wide range of Juniper Junos OS versions, spanning from 19.3R1 through 21.2R2, and includes both traditional Junos OS and Junos OS Evolved variants, indicating a widespread exposure across multiple product lines and release cycles.
The vulnerability aligns with CWE-252, which describes improper checking for unusual conditions, and demonstrates characteristics consistent with the ATT&CK technique T1499.004 for network denial of service attacks. Organizations should prioritize immediate remediation by applying the relevant security patches provided by Juniper Networks, specifically targeting the affected version ranges mentioned in the advisory. Network segmentation and access control measures can provide temporary mitigation by preventing unauthorized adjacent access to critical network infrastructure. Additionally, implementing monitoring solutions to detect unusual CPU utilization patterns and abnormal ISIS adjacency behavior can help identify exploitation attempts. The vulnerability underscores the importance of robust input validation in network protocol implementations and highlights the need for comprehensive testing of edge cases in routing daemon implementations. Security teams should also consider implementing intrusion detection systems capable of identifying malformed ISIS TLV patterns and establishing incident response procedures for handling potential exploitation attempts.