CVE-2017-10621 - Junos OS: Denial of service vulnerability in telnetd

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MEDIUM

Junos OS: Denial of service vulnerability in telnetd

Published Oct 13, 2017

5.3

MEDIUM

CVSS 3.0

EPSS 1.80%

Description

A denial of service vulnerability in telnetd service on Juniper Networks Junos OS allows remote unauthenticated attackers to cause a denial of service. Affected Junos OS releases are: 12.1X46 prior to 12.1X46-D71; 12.3X48 prior to 12.3X48-D50; 14.1 prior to 14.1R8-S5, 14.1R9; 14.1X53 prior to 14.1X53-D50; 14.2 prior to 14.2R7-S9, 14.2R8; 15.1 prior to 15.1F2-S16, 15.1F5-S7, 15.1F6-S6, 15.1R5-S2, 15.1R6; 15.1X49 prior to 15.1X49-D90; 15.1X53 prior to 15.1X53-D47; 16.1 prior to 16.1R4-S1, 16.1R5; 16.2 prior to 16.2R1-S3, 16.2R2;

Affected products

Vendor Juniper Networks Product Junos OS Default
unknown
Affected
- 12.1X46 prior to 12.1X46-D71
- 12.3X48 prior to 12.3X48-D50
- 14.1 prior to 14.1R8-S5, 14.1R9
- 14.1X53 prior to 14.1X53-D50
- 14.2 prior to 14.2R7-S9, 14.2R8
- 15.1 prior to 15.1F2-S16, 15.1F5-S7, 15.1F6-S6, 15.1R5-S2, 15.1R6
- 15.1X49 prior to 15.1X49-D90
- 15.1X53 prior to 15.1X53-D47
- 16.1 prior to 16.1R4-S1, 16.1R5
- 16.2 prior to 16.2R1-S3, 16.2R2

Default status is the baseline for the product. Each version can override it (patched versions can be marked unaffected).

Vendor	Product	Default status	Versions
Juniper Networks	Junos OS	unknown	Affected 12.1X46 prior to 12.1X46-D71 12.3X48 prior to 12.3X48-D50 14.1 prior to 14.1R8-S5, 14.1R9 14.1X53 prior to 14.1X53-D50 14.2 prior to 14.2R7-S9, 14.2R8 15.1 prior to 15.1F2-S16, 15.1F5-S7, 15.1F6-S6, 15.1R5-S2, 15.1R6 15.1X49 prior to 15.1X49-D90 15.1X53 prior to 15.1X53-D47 16.1 prior to 16.1R4-S1, 16.1R5 16.2 prior to 16.2R1-S3, 16.2R2

Remediation

Vendor solution

Disabling the telnet service would completely mitigate this issue.

Reducing the maximum number of connections to a value between 1 and 250 would help mitigate this vulnerability. For example: user@junos# set system services telnet connection-limit 100

It is good security practice to limit the exploitable attack surface of critical infrastructure networking equipment. Use access lists or firewall filters to limit access to the device from trusted, administrative networks or hosts.

Weaknesses (1)

CWE-400

Uncontrolled Resource Consumption