Source: cve@mitre.org
Juniper JUNOS 5.x through JUNOS 7.x allows remote attackers to cause a denial of service (routing disabled) via a large number of MPLS packets, which are not filtered or verified before being sent to the Routing Engine, which reduces the speed at which other packets are processed.
Juniper JUNOS devices are vulnerable to a denial-of-service (DoS) attack. By flooding a target with a large volume of malformed MPLS packets, attackers can overwhelm the Routing Engine, effectively disabling routing and disrupting network connectivity. This vulnerability impacts critical network infrastructure, leading to significant service outages.
Step 1: Packet Crafting: The attacker crafts a large number of MPLS packets. These packets may be valid MPLS packets, but the sheer volume is the key to the attack. The packets do not need to be malformed, but the volume is the key factor.
Step 2: Packet Injection: The attacker sends the crafted MPLS packets to the target Juniper JUNOS device, typically over a network connection.
Step 3: Routing Engine Overload: The JUNOS device receives the MPLS packets and attempts to process them. Because of the high volume, the Routing Engine becomes overwhelmed.
Step 4: Resource Exhaustion: The Routing Engine's resources (CPU, memory) are consumed by processing the flood of MPLS packets.
Step 5: Denial of Service: Legitimate traffic processing slows down or stops completely, leading to a denial of service. Routing functionality is severely impacted or disabled.
The vulnerability stems from insufficient input validation and resource exhaustion within the Juniper JUNOS operating system. Specifically, the Routing Engine fails to adequately filter or rate-limit the processing of MPLS packets. Attackers can exploit this by sending a flood of MPLS packets, overwhelming the Routing Engine's processing capacity. This leads to a slowdown in processing legitimate traffic, effectively causing a DoS. The root cause is a lack of proper resource allocation and rate limiting for MPLS packet processing, allowing an attacker to consume excessive CPU cycles and memory resources. This isn't a specific buffer overflow or memory corruption issue, but rather a design flaw allowing resource starvation.
While specific APT groups are not explicitly linked to this vulnerability, any threat actor seeking to disrupt network operations could leverage this. Nation-state actors and cybercriminals alike could exploit this vulnerability. This vulnerability is not listed on the CISA KEV.
Monitor network traffic for a sudden and sustained increase in MPLS packet volume.
Analyze router CPU utilization; a sustained high CPU load on the Routing Engine is a key indicator.
Examine router logs for error messages related to MPLS processing or resource exhaustion.
Implement network traffic monitoring tools to identify and alert on unusual traffic patterns, especially those involving MPLS packets.
Use intrusion detection systems (IDS) to identify suspicious traffic patterns and potential DoS attacks.
Upgrade to a patched version of JUNOS that addresses the vulnerability. (See Affected Products for specific versions).
Implement rate limiting on MPLS traffic to prevent a flood of packets from overwhelming the Routing Engine.
Configure access control lists (ACLs) to filter MPLS traffic from untrusted sources.
Monitor network traffic and router performance regularly to detect and respond to potential attacks.
Implement a robust incident response plan to address DoS attacks, including mitigation strategies such as traffic filtering and blackholing.
Consider deploying traffic shaping or quality of service (QoS) policies to prioritize critical traffic and mitigate the impact of a DoS attack.