CVE-2022-22174 in Junos OS
Summary
by MITRE • 01/19/2022
A vulnerability in the processing of inbound IPv6 packets in Juniper Networks Junos OS on QFX5000 Series and EX4600 switches may cause the memory to not be freed, leading to a packet DMA memory leak, and eventual Denial of Service (DoS) condition. Once the condition occurs, further packet processing will be impacted, creating a sustained Denial of Service (DoS) condition. The following error logs may be observed using the "show heap" command and the device may eventually run out of memory if such packets are received continuously. Jan 12 12:00:00 device-name fpc0 (buf alloc) failed allocating packet buffer Jan 12 12:00:01 device-name fpc0 (buf alloc) failed allocating packet buffer user@device-name> request pfe execute target fpc0 timeout 30 command "show heap" ID Base Total(b) Free(b) Used(b) % Name -- ---------- ----------- ----------- ----------- --- ----------- 0 246fc1a8 536870488 353653752 183216736 34 Kernel 1 91800000 16777216 12069680 4707536 28 DMA 2 92800000 75497472 69997640 5499832 7 PKT DMA DESC 3 106fc000 335544320 221425960 114118360 34 Bcm_sdk 4 97000000 176160768 200 176160568 99 Packet DMA
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Analysis
by VulDB Data Team • 01/20/2022
This vulnerability represents a critical memory management flaw in Juniper Networks Junos OS affecting QFX5000 Series and EX4600 switches. The issue manifests during the processing of inbound IPv6 packets where the system fails to properly release memory allocated for packet DMA operations. This memory leak occurs specifically within the packet forwarding engine's buffer management system, creating a progressive degradation of system resources that ultimately leads to complete service disruption. The vulnerability operates at the hardware abstraction layer where packet buffers are allocated and managed, making it particularly dangerous as it affects the fundamental packet processing capabilities of the network infrastructure.
The technical implementation of this flaw involves improper memory deallocation mechanisms within the packet DMA subsystem. When IPv6 packets are received and processed, the system allocates memory buffers from the DMA pool but fails to correctly return these buffers to the available memory pool upon packet processing completion. This results in a gradual exhaustion of the packet DMA buffer space as documented in the heap analysis showing the DMA memory segment (ID 1) becoming increasingly consumed while remaining free space diminishes. The error messages indicating "buf alloc failed allocating packet buffer" demonstrate the system's inability to secure new memory resources as existing allocations remain unreleased, creating a cascading effect that prevents normal packet processing operations.
From an operational impact perspective, this vulnerability creates a persistent denial of service condition that can be triggered through continuous receipt of specifically crafted IPv6 packets. The sustained nature of the memory leak means that even brief periods of malicious traffic can cause extended outages, as the system cannot recover from the memory exhaustion without manual intervention or device reboot. Network administrators may observe system performance degradation before complete service failure, with the heap utilization showing dramatic shifts in memory allocation patterns. The attack vector is particularly concerning because it can be executed remotely through network traffic without requiring authentication, making it a significant threat to network availability and reliability.
The vulnerability aligns with CWE-401: "Improper Release of Memory Before Removing Last Reference" and represents a classic memory leak scenario that can be exploited to cause resource exhaustion attacks. This weakness falls under the ATT&CK technique T1499.004: "Endpoint Denial of Service" and can be categorized as a resource exhaustion attack pattern. The attack surface is limited to devices running affected Junos OS versions on the specified hardware platforms, but the impact is severe enough that any network environment relying on these switches for core forwarding functions would be at significant risk. The memory allocation patterns observed in the heap analysis indicate that the system's memory management routines have a fundamental flaw in their buffer lifecycle management, particularly affecting the Packet DMA memory segment which is critical for forwarding operations.
Recommended mitigations include applying the latest security patches provided by Juniper Networks, implementing rate limiting or access control lists to restrict IPv6 traffic, and monitoring system heap utilization for early detection of memory leak conditions. Network administrators should also consider implementing automated alerting for memory exhaustion events and establish procedures for rapid system recovery. The vulnerability highlights the importance of proper memory management in network infrastructure devices and underscores the need for comprehensive testing of buffer allocation and deallocation routines in high-throughput network processing environments. Organizations should also consider implementing network segmentation to limit the potential impact of such attacks and maintain detailed monitoring of system resource utilization to detect anomalous memory consumption patterns.