CVE-2021-0289

Summary

When user-defined ARP Policer is configured and applied on one or more Aggregated Ethernet (AE) interface units, a Time-of-check Time-of-use (TOCTOU) Race Condition vulnerability between the Device Control Daemon (DCD) and firewall process (dfwd) daemons of Juniper Networks Junos OS allows an attacker to bypass the user-defined ARP Policer. In this particular case the User ARP policer is replaced with default ARP policer. To review the desired ARP Policers and actual state one can run the command "show interfaces <> extensive" and review the output. See further details below. An example output is: show interfaces extensive | match policer Policer: Input: default_arp_policer <<< incorrect if user ARP Policer was applied on an AE interface and the default ARP Policer is displayed Policer: Input: jtac-arp-ae5.317-inet-arp <<< correct if user ARP Policer was applied on an AE interface For all platforms, except SRX Series: This issue affects Juniper Networks Junos OS: All versions 5.6R1 and all later versions prior to 18.4 versions prior to 18.4R2-S9, 18.4R3-S9 with the exception of 15.1 versions 15.1R7-S10 and later versions; 19.4 versions prior to 19.4R3-S3; 20.1 versions prior to 20.1R3; 20.2 versions prior to 20.2R3-S2; 20.3 version 20.3R1 and later versions; 20.4 versions prior to 20.4R3; 21.1 versions prior to 21.1R2; This issue does not affect Juniper Networks Junos OS versions prior to 5.6R1. On SRX Series this issue affects Juniper Networks Junos OS: 18.4 versions prior to 18.4R2-S9, 18.4R3-S9; 19.4 versions prior to 19.4R3-S4; 20.1 versions prior to 20.1R3; 20.2 versions prior to 20.2R3-S2; 20.3 version 20.3R1 and later versions; 20.4 versions prior to 20.4R3; 21.1 versions prior to 21.1R2. This issue does not affect 18.4 versions prior to 18.4R1 on SRX Series. This issue does not affect Junos OS Evolved.

Affected Software

VendorProductVersion RangeStatus
Juniper NetworksJunos OSunspecified < 5.6R1unaffected
Juniper NetworksJunos OS5.6R1 < 5.6*affected
Juniper NetworksJunos OS15.1 < 15.1R7-S10affected
Juniper NetworksJunos OS16.1R1 < 16.1*affected
Juniper NetworksJunos OS16.2R1 < 16.2*affected
Juniper NetworksJunos OS17.1R1 < 17.1*affected
Juniper NetworksJunos OS17.2R1 < 17.2*affected
Juniper NetworksJunos OS17.3R1 < 17.3*affected
Juniper NetworksJunos OS17.4R1 < 17.4*affected
Juniper NetworksJunos OS18.1R1 < 18.1*affected
Juniper NetworksJunos OS18.2R1 < 18.2*affected
Juniper NetworksJunos OS18.3R1 < 18.3*affected
Juniper NetworksJunos OS18.4 < 18.4R2-S9, 18.4R3-S9affected
Juniper NetworksJunos OS19.4 < 19.4R3-S3affected
Juniper NetworksJunos OS20.1 < 20.1R3affected
Juniper NetworksJunos OS20.2 < 20.2R3-S2affected
Juniper NetworksJunos OS20.3R1 < 20.3*affected
Juniper NetworksJunos OS20.4 < 20.4R3affected
Juniper NetworksJunos OS21.1 < 21.1R2affected
Juniper NetworksJunos OS18.4 < 18.4R2-S9, 18.4R3-S9affected
Juniper NetworksJunos OS19.4 < 19.4R3-S3affected
Juniper NetworksJunos OS20.1 < 20.1R3affected
Juniper NetworksJunos OS20.2 < 20.2R3-S2unaffected
Juniper NetworksJunos OS20.3R1 < 20.3*affected
Juniper NetworksJunos OS20.4 < 20.4R3affected
Juniper NetworksJunos OS21.1 < 21.1R2affected
Juniper NetworksJunos OS EvolvedAnyunaffected

Weaknesses

  • CWE-367: CWE-367 Time-of-check Time-of-use (TOCTOU) Race Condition

Workarounds

There is no workaround for this issue.

If affected by this issue, to recover from its impact, restart the firewall process to update the ARP Policer on the AE interface unit(s).
From the CLI issue:

cli> restart firewall

Note: no side effects on firewall restart shall be seen when issuing this command.

ADP Enrichment

CVE Program Container

Additional References

References