CVE-2020-1644 in Junos
Summary
by MITRE
On Juniper Networks Junos OS and Junos OS Evolved devices, the receipt of a specific BGP UPDATE packet causes an internal counter to be incremented incorrectly, which over time can lead to the routing protocols process (RPD) crash and restart. This issue affects both IBGP and EBGP multihop deployment in IPv4 or IPv6 network. This issue affects: Juniper Networks Junos OS: 17.2X75 versions prior to 17.2X75-D105.19; 17.3 versions prior to 17.3R3-S8; 17.4 versions prior to 17.4R2-S10, 17.4R3-S2; 18.1 versions prior to 18.1R3-S10; 18.2 versions prior to 18.2R2-S7, 18.2R3-S4; 18.2X75 versions prior to 18.2X75-D13, 18.2X75-D411.1, 18.2X75-D420.18, 18.2X75-D52.3, 18.2X75-D60; 18.3 versions prior to 18.3R2-S4, 18.3R3-S2; 18.4 versions prior to 18.4R1-S7, 18.4R2-S4, 18.4R3-S2; 19.1 versions prior to 19.1R1-S5, 19.1R2-S1, 19.1R3; 19.2 versions prior to 19.2R1-S5, 19.2R2; 19.3 versions prior to 19.3R2-S2, 19.3R3; 19.4 versions prior to 19.4R1-S2, 19.4R2. Juniper Networks Junos OS Evolved: any releases prior to 20.1R2-EVO. This issue does not affect Juniper Networks Junos OS releases prior to 17.3R1.
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Analysis
by VulDB Data Team • 11/04/2020
This vulnerability represents a critical denial of service weakness in Juniper Networks Junos OS and Junos OS Evolved implementations that specifically targets the Border Gateway Protocol (BGP) routing process. The flaw manifests when devices receive specially crafted BGP UPDATE packets that trigger an incorrect increment of an internal counter within the routing protocols daemon (RPD). This counter overflow condition ultimately leads to the RPD process crashing and restarting, effectively disrupting network routing operations and potentially causing temporary network outages. The vulnerability demonstrates characteristics consistent with CWE-129, an improper validation of an input buffer, as it involves malformed input data that causes internal state corruption rather than direct memory corruption.
The technical exploitation of this vulnerability requires an attacker to send specifically formatted BGP UPDATE messages to affected Junos OS devices, which can be accomplished through either internal or external network access points where BGP sessions are established. The impact extends across all BGP deployment scenarios including both internal BGP (IBGP) and external BGP (EBGP) configurations, operating over both IPv4 and IPv6 address families. This broad scope makes the vulnerability particularly dangerous as it can affect routing operations in diverse network environments including service provider backbones, enterprise networks, and data center infrastructures where Junos devices are deployed.
The operational consequences of this vulnerability are significant as it can lead to routing instability and service disruption across affected networks. Network administrators may experience unexpected routing protocol flapping, where BGP sessions repeatedly establish and tear down, causing temporary loss of connectivity and potential routing loops. The vulnerability affects multiple software versions spanning from 17.2X75 through 19.4 releases, indicating this was a persistent issue that required multiple patches across different release trains. The specific versions requiring updates demonstrate that the issue was not isolated to a single software release but affected the broader Junos OS ecosystem, making it a widespread concern for organizations maintaining multiple Juniper device deployments.
Organizations should prioritize immediate remediation through official Juniper security advisories and software updates that address the counter increment logic within the RPD process. The mitigation strategy aligns with ATT&CK technique T1499.004, which involves defending against network disruption attacks by implementing proper input validation and process monitoring. Network segmentation and access control measures should be implemented to limit exposure to potentially malicious BGP UPDATE packets, while monitoring systems should be configured to detect unusual routing protocol behavior that could indicate exploitation attempts. The vulnerability highlights the importance of maintaining current security patches and implementing network access controls to prevent unauthorized parties from exploiting routing protocol weaknesses that could compromise entire network infrastructures.
The vulnerability's classification as a denial of service issue places it within the broader category of network infrastructure attacks that can have cascading effects across interconnected networks. Given that BGP is fundamental to internet routing operations, exploitation of this vulnerability could potentially cause widespread disruption if multiple devices in a network path are affected. Organizations should also consider implementing BGP monitoring and filtering mechanisms to detect and prevent malformed UPDATE packets from entering their routing domains, as this represents a proactive defense measure against similar vulnerabilities in the routing protocol stack. The patching process for this vulnerability requires careful planning and testing to ensure that network stability is maintained during the update process while addressing the underlying counter increment flaw that leads to process crashes.