CVE-2018-0004 in Junos
Summary
by MITRE
A sustained sequence of different types of normal transit traffic can trigger a high CPU consumption denial of service condition in the Junos OS register and schedule software interrupt handler subsystem when a specific command is issued to the device. This affects one or more threads and conversely one or more running processes running on the system. Once this occurs, the high CPU event(s) affects either or both the forwarding and control plane. As a result of this condition the device can become inaccessible in either or both the control and forwarding plane and stops forwarding traffic until the device is rebooted. The issue will reoccur after reboot upon receiving further transit traffic. Score: 5.7 MEDIUM (CVSS:3.0/AV:A/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H) For network designs utilizing layer 3 forwarding agents or other ARP through layer 3 technologies, the score is slightly higher. Score: 6.5 MEDIUM (CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H) If the following entry exists in the RE message logs then this may indicate the issue is present. This entry may or may not appear when this issue occurs. /kernel: Expensive timeout(9) function: Affected releases are Juniper Networks Junos OS: 12.1X46 versions prior to 12.1X46-D50; 12.3X48 versions prior to 12.3X48-D30; 12.3R versions prior to 12.3R12-S7; 14.1 versions prior to 14.1R8-S4, 14.1R9; 14.1X53 versions prior to 14.1X53-D30, 14.1X53-D34; 14.2 versions prior to 14.2R8; 15.1 versions prior to 15.1F6, 15.1R3; 15.1X49 versions prior to 15.1X49-D40; 15.1X53 versions prior to 15.1X53-D31, 15.1X53-D33, 15.1X53-D60. No other Juniper Networks products or platforms are affected by this issue.
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Analysis
by VulDB Data Team • 01/20/2023
This vulnerability represents a sophisticated denial of service condition that exploits the Junos OS register and schedule software interrupt handler subsystem through sustained sequences of normal transit traffic. The flaw manifests when specific commands are issued to the device, triggering excessive CPU consumption that affects multiple threads and running processes across the system. The vulnerability operates at the kernel level, specifically targeting the interrupt handling mechanisms that govern system responsiveness and resource allocation. The technical implementation involves a cascade effect where the initial command triggers a timeout function that becomes increasingly expensive over time, ultimately consuming system resources to the point of complete device inaccessibility. This condition affects both the forwarding and control plane simultaneously, creating a comprehensive system failure that prevents normal network operations.
The operational impact of CVE-2018-0004 extends beyond simple service disruption to create complete system unavailability that requires reboot to resolve. The vulnerability's behavior demonstrates characteristics consistent with a resource exhaustion attack pattern, where legitimate network traffic becomes weaponized to consume system resources. The issue affects multiple Junos OS versions across different release branches, indicating a fundamental flaw in the interrupt handling subsystem that was not properly addressed across the product line. Network designs utilizing layer 3 forwarding agents or ARP through layer 3 technologies face elevated risk due to the increased complexity of their forwarding paths, which can amplify the vulnerability's impact. The CVSS scores reflect this elevated risk, with network-based attacks achieving a medium severity rating of 5.7 and local attacks with user interaction achieving a slightly higher rating of 6.5, demonstrating the vulnerability's exploitation potential across different attack vectors.
The vulnerability's persistence after reboot operations indicates that the underlying software flaw remains unaddressed in the affected versions, creating a recurring security risk that requires ongoing monitoring and mitigation strategies. The specific log entry "/kernel: Expensive timeout(9) function:" serves as an indicator that may help identify affected systems, though its presence is not guaranteed during all vulnerability manifestations. This characteristic aligns with the MITRE CWE classification for resource exhaustion vulnerabilities, specifically CWE-400, which encompasses issues where systems fail to properly manage resource consumption. The attack pattern also maps to ATT&CK technique T1499.004, which covers network disruption through resource exhaustion, demonstrating how this vulnerability can be leveraged in sophisticated attack scenarios. The affected release versions span multiple Junos OS branches, including 12.1X46, 12.3X48, 12.3R, 14.1, 14.1X53, 14.2, 15.1, 15.1X49, and 15.1X53, indicating a widespread impact across the Juniper product line that required coordinated patch management across different release streams. The vulnerability's exploitation requires only normal network traffic patterns and specific command issuance, making it particularly dangerous as it can be triggered by legitimate network operations without requiring specialized attack tools or privileges. Organizations must implement comprehensive monitoring strategies to detect the expensive timeout function indicators and ensure timely patch deployment across all affected Junos OS versions to prevent system compromise and maintain network availability.