CVE-2020-1627 in Junos
Summary
by MITRE
A vulnerability in Juniper Networks Junos OS on vMX and MX150 devices may allow an attacker to cause a Denial of Service (DoS) by sending specific packets requiring special processing in microcode that the flow cache can't handle, causing the riot forwarding daemon to crash. By continuously sending the same specific packets, an attacker can repeatedly crash the riot process causing a sustained Denial of Service. Flow cache is specific to vMX based products and the MX150, and is enabled by default in performance mode. This issue can only be triggered by traffic destined to the device. Transit traffic will not cause the riot daemon to crash. When the issue occurs, a core dump and riot log file entry are generated. For example: /var/crash/core.J-UKERN.mpc0.1557255993.3864.gz /home/pfe/RIOT logs: fpc0 riot[1888]: PANIC in lu_reorder_send_packet_postproc(): fpc0 riot[6655]: PANIC in lu_reorder_send_packet_postproc(): This issue affects Juniper Networks Junos OS: 18.1 versions prior to 18.1R3 on vMX and MX150; 18.2 versions prior to 18.2R3 on vMX and MX150; 18.2X75 versions prior to 18.2X75-D60 on vMX and MX150; 18.3 versions prior to 18.3R3 on vMX and MX150; 18.4 versions prior to 18.4R2 on vMX and MX150; 19.1 versions prior to 19.1R2 on vMX and MX150. This issue does not affect Junos OS versions prior to 18.1R1.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 05/17/2024
This vulnerability represents a critical denial of service weakness in Juniper Networks Junos OS affecting specific hardware platforms including vMX and MX150 devices. The flaw manifests when specially crafted packets are transmitted to the device, triggering microcode processing that exceeds the flow cache capabilities of these particular platforms. The flow cache mechanism, which is specifically implemented for vMX-based products and MX150 devices, operates in performance mode by default and becomes the point of failure when processing these targeted packets. The vulnerability stems from insufficient handling of packet processing within the riot forwarding daemon, which is responsible for packet forwarding operations on these platforms.
The technical implementation of this vulnerability involves the lu_reorder_send_packet_postproc() function within the riot daemon, where a panic condition occurs during packet processing. This panic results in the complete crash of the riot process, which serves as the core forwarding component for these devices. The crash generates diagnostic information including core dump files and log entries that clearly indicate the failure point in the code execution flow. The specific error messages reference fpc0 riot[1888]: PANIC in lu_reorder_send_packet_postproc() and fpc0 riot[6655]: PANIC in lu_reorder_send_packet_postproc(), demonstrating the consistent failure pattern across different instances of the daemon. The vulnerability requires that traffic be specifically destined to the affected device rather than passing through it as transit traffic, limiting the attack surface but still maintaining significant operational impact.
Operational impact of this vulnerability extends beyond simple service disruption to potentially sustained denial of service conditions that can severely compromise network availability. The ability to repeatedly crash the riot process through continuous packet injection allows attackers to maintain persistent service interruption without requiring additional authentication or complex attack vectors. Network administrators face the challenge of maintaining service continuity on critical infrastructure while dealing with the potential for repeated service outages that could affect business operations. The core dump generation and log file creation provide forensic evidence but also represent additional resource consumption that may compound the operational impact during active attacks.
The vulnerability affects multiple software versions across different release branches of Junos OS, specifically targeting versions prior to the respective security patches. This includes 18.1 versions before 18.1R3, 18.2 versions before 18.2R3, 18.2X75 versions before 18.2X75-D60, 18.3 versions before 18.3R3, 18.4 versions before 18.4R2, and 19.1 versions before 19.1R2. The absence of this vulnerability in versions prior to 18.1R1 indicates that the specific microcode handling was introduced in later releases, making the affected platforms particularly vulnerable during their operational lifecycle. This vulnerability aligns with CWE-121, which addresses stack-based buffer overflow conditions, and represents a memory corruption issue that can lead to process termination and system instability. From an ATT&CK perspective, this vulnerability maps to the T1499.004 technique related to network disruption attacks, specifically targeting network availability through process termination. Mitigation strategies should include immediate deployment of vendor security patches, network segmentation to limit exposure, and monitoring for suspicious packet patterns that may indicate exploitation attempts.