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2021-04 Security Bulletin: Junos OS: MX Series: DDoS LACP violation upon receipt of specific layer 2 frames in EVPN-VXLAN deployment (CVE-2021-0228)

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Article ID: JSA11123 SECURITY_ADVISORIES Last Updated: 14 Apr 2021Version: 1.0
Product Affected:
This issue affects Junos OS 15.1, 17.3, 17.4, 18.1, 18.2, 18.3, 18.4, 19.1, 19.2, 19.3, 19.4, 20.1, 20.2, 20.3. Affected platforms: MX Series.
Problem:

An improper check for unusual or exceptional conditions vulnerability in Juniper Networks MX Series platforms with Trio-based MPC (Modular Port Concentrator) deployed in (Ethernet VPN) EVPN-(Virtual Extensible LAN) VXLAN configuration, may allow an attacker sending specific Layer 2 traffic to cause Distributed Denial of Service (DDoS) protection to trigger unexpectedly, resulting in traffic impact.

Continued receipt and processing of this specific Layer 2 frames will sustain the Denial of Service (DoS) condition.

An indication of compromise is to check DDOS LACP violations:

user@device> show ddos-protection protocols statistics brief | match lacp

This issue only affects the MX Series platforms with Trio-based MPC. No other products or platforms are affected.

This issue affects:

Juniper Networks Junos OS on MX Series:

  • 15.1 versions prior to 15.1R7-S9;
  • 17.3 versions prior to 17.3R3-S11;
  • 17.4 versions prior to 17.4R3-S4;
  • 18.1 versions prior to 18.1R3-S12;
  • 18.2 versions prior to 18.2R2-S8, 18.2R3-S8;
  • 18.3 versions prior to 18.3R3-S4;
  • 18.4 versions prior to 18.4R1-S8, 18.4R2-S7, 18.4R3-S7;
  • 19.1 versions prior to 19.1R3-S4;
  • 19.2 versions prior to 19.2R1-S6;
  • 19.3 versions prior to 19.3R3-S2;
  • 19.4 versions prior to 19.4R2-S4, 19.4R3-S2;
  • 20.1 versions prior to 20.1R2, 20.1R3;
  • 20.2 versions prior to 20.2R2-S1, 20.2R3;
  • 20.3 versions prior to 20.3R1-S1, 20.3R2;

The DDoS feature is enabled by default, there is no specific config stanza required to enable DDoS protection.

The example of EVPN-VXLAN configuration stanza affected by this issue is as follows:

[protocols evpn]

[routing-instances <name> protocols evpn]

Juniper SIRT is not aware of any malicious exploitation of this vulnerability.

This issue was seen during production usage.

This issue has been assigned CVE-2021-0228.

Solution:

The following software releases have been updated to resolve this specific issue: 15.1R7-S9, 17.3R3-S11, 17.4R3-S4, 18.1R3-S12, 18.2R2-S8, 18.2R3-S8, 18.3R3-S4, 18.4R1-S8, 18.4R2-S7, 18.4R3-S7, 19.1R3-S4, 19.2R1-S6, 19.3R3-S2, 19.4R2-S4, 19.4R3-S2, 20.1R2, 20.1R3, 20.2R2-S1, 20.2R3, 20.3R1-S1, 20.3R2, 20.4R1, and all subsequent releases.

This issue is being tracked as 1512033.

Workaround:

DDoS for LACP can be disabled:

set system ddos-protection protocols lacp aggregate disable-routing-engine
set system ddos-protection protocols lacp aggregate disable-fpc
Implementation:
Software releases or updates are available for download at https://support.juniper.net/support/downloads/
Modification History:
2021-04-14: Initial Publication.
CVSS Score:
6.5 (CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
Severity Level:
Medium
Severity Assessment:
Information for how Juniper Networks uses CVSS can be found at KB 16446 "Common Vulnerability Scoring System (CVSS) and Juniper's Security Advisories."

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