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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)

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

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


CVE-2021-0284 affects:

Juniper Networks Junos OS

  • All versions prior to 17.3R3-S12;
  • 19.3 versions prior to 19.3R3-S3;
  • 19.4 versions prior to 19.4R3-S5;
  • 20.2 versions prior to 20.2R3-S2;
  • 20.4 versions prior to 20.4R3;
  • 21.1 versions prior to 21.1R2;
  • 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
CVE-2021-0283 7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) 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-2021-0284 7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) ** RESERVED ** This candidate has been reserved by Juniper Networks, Inc. When the candidate has been publicized, the details for this candidate will be provided.
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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