CVE-2020-1608 in Junos
Summary
by MITRE
Receipt of a specific MPLS or IPv6 packet on the core facing interface of an MX Series device configured for Broadband Edge (BBE) service may trigger a kernel crash (vmcore), causing the device to reboot. The issue is specific to the processing of packets destined to BBE clients connected to MX Series subscriber management platforms. This issue affects MX Series running Juniper Networks Junos OS: 17.2 versions starting from17.2R2-S6, 17.2R3 and later releases, prior to 17.2R3-S3; 17.3 versions starting from 17.3R2-S4, 17.3R3-S2 and later releases, prior to 17.3R2-S5, 17.3R3-S5; 17.4 versions starting from 17.4R2 and later releases, prior to 17.4R2-S7,17.4R3; 18.1 versions starting from 18.1R2-S3, 18.1R3 and later releases, prior to 18.1R3-S6; 18.2 versions starting from18.2R1-S1, 18.2R2 and later releases, prior to 18.2R3-S2; 18.2X75 versions prior to 18.2X75-D51, 18.2X75-D60; 18.3 versions prior to 18.3R3; 18.4 versions prior to 18.4R2; 19.1 versions prior to 19.1R1-S3, 19.1R2; 19.2 versions prior to 19.2R1-S2, 19.2R2. This issue does not affect Juniper Networks Junos OS versions prior to 17.2R2-S6.
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Analysis
by VulDB Data Team • 03/24/2024
The vulnerability described in CVE-2020-1608 represents a critical kernel crash condition affecting Juniper MX Series routers operating within Broadband Edge service configurations. This issue manifests when specific MPLS or IPv6 packets are received on core-facing interfaces connected to subscriber management platforms, resulting in system-wide kernel panics that trigger automatic device reboots. The flaw specifically targets the packet processing mechanisms employed by the Broadband Edge service implementation, making it particularly dangerous for network infrastructure where continuous uptime is essential for service delivery. The vulnerability demonstrates characteristics consistent with a buffer overflow or memory corruption issue, where malformed packet structures cause the kernel to fail during processing operations.
The technical implementation of this vulnerability stems from improper handling of packet validation within the kernel's network processing stack. When packets destined for BBE clients are received, the system fails to properly validate or sanitize incoming MPLS or IPv6 packet headers before processing them through the Broadband Edge service logic. This failure allows specially crafted packets to exploit memory access patterns that result in kernel memory corruption, ultimately leading to a vmcore dump and system reboot. The vulnerability's specificity to MX Series devices running Junos OS versions within the affected release ranges indicates a targeted flaw in the kernel's packet processing modules rather than a broader architectural issue.
Operational impact of this vulnerability extends beyond simple service disruption to encompass potential network reliability degradation and customer service interruptions. The automatic reboot behavior creates a cascading effect where network services may experience extended downtime while devices restart and re-establish connections. Network administrators face the challenge of maintaining service availability during the vulnerability window, as the issue can be triggered remotely through network traffic without requiring authentication or physical access to the device. The vulnerability affects multiple Junos OS release lines simultaneously, indicating a fundamental flaw in the packet processing logic that was not properly addressed across different software versions, making it a widespread concern for organizations maintaining diverse router fleets.
Mitigation strategies for CVE-2020-1608 require immediate implementation of firmware updates to affected Junos OS versions, with particular attention to the specific release ranges mentioned in the advisory. Network administrators should prioritize patching devices running affected software versions to prevent exploitation, as the vulnerability can be leveraged for denial-of-service attacks that compromise network availability. Additionally, implementing network segmentation and access control measures can help reduce exposure by limiting the types of packets that can reach core-facing interfaces. The vulnerability aligns with CWE-125: Out-of-bounds Read and CWE-787: Out-of-bounds Write categories, indicating memory corruption issues that can be exploited through packet injection attacks. Organizations should also consider implementing monitoring solutions to detect anomalous packet patterns that might indicate exploitation attempts, as the vulnerability operates at the kernel level where traditional network security controls may not effectively prevent the attack. The ATT&CK framework categorizes this vulnerability under T1499.004: Endpoint Denial of Service, highlighting the potential for attackers to leverage this flaw for service disruption attacks that target network infrastructure reliability.