CVE-2020-1680 in Junos
Summary
by MITRE • 10/17/2020
On Juniper Networks MX Series with MS-MIC or MS-MPC card configured with NAT64 configuration, receipt of a malformed IPv6 packet may crash the MS-PIC component on MS-MIC or MS-MPC. This issue occurs when a multiservice card is translating the malformed IPv6 packet to IPv4 packet. An unauthenticated attacker can continuously send crafted IPv6 packets through the device causing repetitive MS-PIC process crashes, resulting in an extended Denial of Service condition. This issue affects Juniper Networks Junos OS on MX Series: 15.1 versions prior to 15.1R7-S7; 15.1X53 versions prior to 15.1X53-D593; 16.1 versions prior to 16.1R7-S8; 17.2 versions prior to 17.2R3-S4; 17.3 versions prior to 17.3R3-S6; 17.4 versions prior to 17.4R2-S11, 17.4R3; 18.1 versions prior to 18.1R3-S11; 18.2 versions prior to 18.2R3-S6; 18.2X75 versions prior to 18.2X75-D41, 18.2X75-D430, 18.2X75-D53, 18.2X75-D65; 18.3 versions prior to 18.3R2-S4, 18.3R3; 18.4 versions prior to 18.4R2-S5, 18.4R3; 19.1 versions prior to 19.1R2; 19.2 versions prior to 19.2R1-S5, 19.2R2; 19.3 versions prior to 19.3R2.
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Analysis
by VulDB Data Team • 11/20/2020
This vulnerability affects Juniper Networks MX Series routers equipped with MS-MIC or MS-MPC cards configured with NAT64 functionality, representing a critical denial of service threat that stems from improper handling of malformed IPv6 packets within the multiservice card processing pipeline. The flaw manifests when these specialized cards attempt to translate malformed IPv6 packets into IPv4 format, triggering a process crash in the MS-PIC component that governs packet processing on these hardware modules. The vulnerability operates at the network protocol level and specifically targets the IPv6 to IPv4 translation mechanisms inherent in NAT64 configurations, making it particularly dangerous for networks that rely on this functionality for IPv6 transition services. The issue demonstrates characteristics of a buffer overflow condition or memory corruption scenario where the packet processing logic fails to properly validate incoming IPv6 packet structures before attempting translation operations.
The operational impact of this vulnerability extends beyond simple service disruption, creating a persistent denial of service condition that can be continuously exploited by unauthenticated attackers. Attackers can repeatedly send crafted IPv6 packets through the affected device, causing the MS-PIC component to repeatedly crash and restart, effectively maintaining the denial of service state for extended periods. This continuous crash loop prevents legitimate traffic from flowing through the router while consuming system resources in the restart process, potentially leading to complete service outages. The vulnerability affects multiple Junos OS versions across several release branches, indicating it represents a fundamental flaw in the packet processing logic rather than a specific implementation error in one version. The attack vector requires no authentication credentials and can be executed from any network location that can reach the affected router, making it particularly dangerous in environments where such devices are exposed to untrusted networks.
From a cybersecurity perspective, this vulnerability maps directly to CWE-121, which describes buffer overflow conditions in stack-based buffers, and potentially CWE-125, which covers out-of-bounds read vulnerabilities. The issue also aligns with ATT&CK technique T1498.001, which involves network denial of service attacks, and T1071.004, which covers application layer protocol usage. The flaw represents a classic case of inadequate input validation where malformed data is processed without proper bounds checking or error handling mechanisms. The vulnerability's exploitation requires minimal technical knowledge and can be automated, making it attractive to threat actors seeking to disrupt network services. The affected hardware components include MS-MIC and MS-MPC cards that are integral to the multiservice routing capabilities of Juniper MX Series devices, indicating that this issue impacts core routing functionality rather than just specific services. Organizations running these vulnerable configurations face significant risk as the attack can be sustained indefinitely, potentially causing extended network outages while the device remains in a crash-restart cycle.
Mitigation strategies should prioritize immediate deployment of Juniper's security patches and firmware updates addressing the specific version ranges mentioned in the vulnerability description, as these releases contain the necessary code modifications to properly validate IPv6 packet structures before translation operations. Network administrators should consider implementing traffic filtering mechanisms at network boundaries to block suspicious IPv6 traffic patterns that could trigger the vulnerability, particularly focusing on packets with malformed headers or unusual fragmentation patterns. The implementation of monitoring solutions that can detect repeated MS-PIC crashes or restart events provides early warning capabilities for potential exploitation attempts. Organizations should also consider temporarily disabling NAT64 functionality on affected devices until permanent patches are deployed, though this may impact network services that depend on IPv6 to IPv4 translation. Additionally, network segmentation strategies can limit the potential impact of successful exploitation by isolating affected routers from critical network segments. Regular vulnerability assessments should be conducted to identify other potential attack vectors within the Junos OS environment, as this vulnerability demonstrates the importance of robust input validation in network infrastructure components. The incident highlights the necessity of maintaining current security patches and implementing comprehensive network monitoring to detect anomalous behavior patterns that could indicate exploitation attempts.