CVE-2020-1679 : Exploit Details and Defense Strategies

This CVE-2020-1679 relates to a vulnerability in Juniper Networks Junos OS affecting PTX and QFX Series devices. When tunnel-observation mpls-over-udp configuration is enabled, a malformed packet sampling can cause the Kernel Routing Table (KRT) queue to become stuck.

Understanding CVE-2020-1679

This vulnerability impacts Junos OS on PTX/QFX Series devices, potentially leading to unexpected packet forwarding issues.

What is CVE-2020-1679?

CVE-2020-1679 arises from packet sampling issues on Juniper Networks PTX and QFX Series devices configured with tunnel-observation mpls-over-udp, resulting in a stuck KRT queue.

The Impact of CVE-2020-1679

The vulnerability can disrupt packet forwarding by causing the KRT queue to stall due to sampled malformed packets, affecting system stability and performance.

Technical Details of CVE-2020-1679

This section delves into the specific technical aspects of the vulnerability.

Vulnerability Description

When sampling malformed packets on Juniper PTX/QFX devices, the KRT queue may freeze, impeding routing and packet forwarding operations.

Affected Systems and Versions

Platforms: PTX, QFX
Affected Versions: 17.2X75-D105, 18.1R3-S11, 18.2R3-S5, 18.2X75-D420, 18.2X75-D53, 18.2X75-D65, 18.3R2-S4, 18.3R3-S3, 18.4R1-S7, 18.4R2-S5, 18.4R3-S4, 19.1R2-S2, 19.1R3-S2, 19.2R1-S5, 19.2R3, 19.3R2-S3, 19.3R3, 19.4R1-S2, 19.4R2-S1, 19.4R3, 20.1R1-S2, 20.1R2

Exploitation Mechanism

There is no known malicious exploitation of this vulnerability reported by Juniper SIRT.

Mitigation and Prevention

To address CVE-2020-1679 and enhance system security, the following measures should be taken:

Immediate Steps to Take

Disable sampling on all interfaces to prevent KRT queue issues.
For affected devices, follow specific steps to restore KRT queue as outlined by Juniper.

Long-Term Security Practices

Ensure all devices are updated with patched software versions provided by Junos OS.
Regularly monitor system logs and KRT queues for abnormalities.

Patching and Updates

Apply software updates to Junos OS versions 17.2X75-D105, 18.1R3-S11, 18.2R3-S5, and subsequent releases to mitigate CVE-2020-1679.