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   JSA11123 - 2021-04 Security Bulletin: Junos OS: MX Series: DDoS LACP
violation upon receipt of specific layer 2 frames in EVPN-VXLAN deployment
                               15 April 2021


        AusCERT Security Bulletin Summary

Product:           Junos OS: MX Series
Publisher:         Juniper Networks
Operating System:  Juniper
Impact/Access:     Denial of Service -- Remote/Unauthenticated
Resolution:        Patch/Upgrade
CVE Names:         CVE-2021-0228  

Original Bulletin: 

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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)

Article ID  : JSA11123
Last Updated: 14 Apr 2021
Version     : 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.


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:

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

[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 .


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 .


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
Software releases or updates are available for download at https://
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:
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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