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             AUSCERT External Security Bulletin Redistribution

                               ESB-2021.2435
 JSA11200 - 2021-07 Security Bulletin: Junos OS: Upon receipt of specific
 sequences of genuine packets destined to the device the kernel will crash
            and restart (vmcore) (CVE-2021-0283, CVE-2021-0284)
                               20 July 2021

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        AusCERT Security Bulletin Summary
        ---------------------------------

Product:           Junos OS
Publisher:         Juniper Networks
Operating System:  Juniper
Impact/Access:     Denial of Service -- Remote/Unauthenticated
Resolution:        Patch/Upgrade
CVE Names:         CVE-2021-0284 CVE-2021-0283 

Original Bulletin: 
   http://kb.juniper.net/InfoCenter/index?page=content&id=JSA11200

- --------------------------BEGIN INCLUDED TEXT--------------------

2021-07 Security Bulletin: Junos OS: Upon receipt of specific sequences of genuine packets destined to the device the kernel will crash and restart (vmcore) (CVE-2021-0283, CVE-2021-0284)

Article ID  : JSA11200
Last Updated: 19 Jul 2021
Version     : 3.0

Product Affected:
This issue affects Junos OS 12.3, 15.1, 16.1, 16.2, 17.1, 17.2, 17.3, 18.1,
18.2, 18.3, 18.4, 19.1, 19.2, 19.3, 19.4, 20.1, 20.2, 20.3, 20.4, 21.1, 21.2.
Problem:

A buffer overflow vulnerability in the TCP/IP stack of Juniper Networks Junos
OS allows an attacker to send specific sequences of packets to the device
thereby causing a Denial of Service (DoS).

By repeatedly sending these sequences of packets to the device, an attacker can
sustain the Denial of Service (DoS) condition.

The device will abnormally shut down as a result of these sent packets. A
potential indicator of compromise will be the following message in the log
files:

eventd[13955]: SYSTEM_ABNORMAL_SHUTDOWN: System abnormally shut down

These issue are only triggered by traffic destined to the device. Transit
traffic will not trigger these issues.

CVE-2021-0283 affects:

Juniper Networks Junos OS

  o 12.3 versions prior to 12.3R12-S19;
  o 15.1 versions prior to 15.1R7-S10;
  o 16.1 version 16.1R1 and later versions;
  o 16.2 version 16.2R1 and later versions;
  o 17.1 version 17.1R1 and later versions;
  o 17.2 version 17.2R1 and later versions;
  o 17.3 version 17.3R1 and later versions;
  o 18.1 versions prior to 18.1R3-S13;
  o 18.2 version 18.2R1 and later versions;
  o 18.3 versions prior to 18.3R3-S5;
  o 18.4 versions prior to 18.4R3-S9;
  o 19.1 versions prior to 19.1R3-S6;
  o 19.2 versions prior to 19.2R3-S3;
  o 19.3 versions prior to 19.3R3-S3;
  o 19.4 versions prior to 19.4R1-S4, 19.4R3-S5;
  o 20.1 versions prior to 20.1R2-S2, 20.1R3-S1;
  o 20.2 versions prior to 20.2R3-S2;
  o 20.3 versions prior to 20.3R3;
  o 20.4 versions prior to 20.4R2-S1, 20.4R3;
  o 21.1 versions prior to 21.1R1-S1, 21.1R2;
  o 21.2 versions prior to 21.2R2.

CVE-2021-0284 affects:

Juniper Networks Junos OS

  o All versions prior to 17.3R3-S12;
  o 19.3 versions prior to 19.3R3-S3;
  o 19.4 versions prior to 19.4R3-S5;
  o 20.2 versions prior to 20.2R3-S2;
  o 20.4 versions prior to 20.4R3;
  o 21.1 versions prior to 21.1R2;
  o 21.2 versions prior to 21.2R2.

CVE-2021-0283 was seen during production usage.

CVE-2021-0284 was found during internal product security testing or research.

Juniper SIRT is not aware of any malicious exploitation of either CVE-2021-0283
or CVE-2021-0284 vulnerabilities.

Juniper SIRT is aware of CVE-2021-0283 occurring in production. In all reported
cases the Junos device was not the intended target of the attack, but this
vulnerability was still triggered.

This issue was seen during production usage.

     CVE         CVSS                            Summary
                          A buffer overflow vulnerability in the TCP/IP stack
                          of Juniper Networks Junos OS allows an attacker to
                          send specific sequences of packets to the device
                          thereby causing a Denial of Service (DoS). By
              7.5 (       repeatedly sending these sequences of packets to the
              CVSS:3.1/   device, an attacker can sustain the Denial of Service
CVE-2021-0283 AV:N/AC:L/  (DoS) condition. The device will abnormally shut down
              PR:N/UI:N/  as a result of these sent packets. A potential
              S:U/C:N/I:N indicator of compromise will be the following message
              /A:H )      in the log files: "eventd[13955]:
                          SYSTEM_ABNORMAL_SHUTDOWN: System abnormally shut
                          down" These issue are only triggered by traffic
                          destined to the device. Transit traffic will not
                          trigger these issues.
              7.5 (
              CVSS:3.1/   ** RESERVED ** This candidate has been reserved by
CVE-2021-0284 AV:N/AC:L/  Juniper Networks, Inc. When the candidate has been
              PR:N/UI:N/  publicized, the details for this candidate will be
              S:U/C:N/I:N provided.
              /A:H )

Solution:

The following software releases have been updated to resolve CVE-2021-0283:
Junos OS: 12.3R12-S19, 15.1R7-S10, 18.1R3-S13, 18.3R3-S5, 18.4R3-S9, 19.1R3-S6,
19.2R3-S3, 19.3R3-S3, 19.4R1-S4, 19.4R3-S5, 20.1R2-S2, 20.1R3-S1, 20.2R3-S2,
20.3R3, 20.4R2-S1, 20.4R3, 21.1R1-S1, 21.1R2, 21.2R2, 21.3R1, and all
subsequent releases.

The following software releases have been tentatively updated to resolved for
CVE-2021-0284: Junos OS: 17.3R3-S12, 19.3R3-S3, 19.4R3-S5, 20.2R3-S2, 20.4R3,
21.1R2, 21.2R2, 21.3R1, and all subsequent releases.

Additional fixes for CVE-2021-0284 are underway and this advisory will be
updated to reflect those fixes as full fixes become available. In the meantime
customers should follow the workaround section and verify they have proper
applied security BCPs on management interfaces.

This issue is being tracked as 1557881 and 1595649 .

Workaround:

There are no available workarounds for these issues.

To reduce the risk of exploitation of these issues, use access lists or
firewall filters to limit access to the device to only trusted administrative
networks, hosts and users.

Implementation:
Software releases or updates are available for download at https://
support.juniper.net/support/downloads/
Modification History:

2021-07-14: Initial Publication.

CVSS Score:
7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)
Severity Level:
High
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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