Support Support Downloads Knowledge Base Case Manager My Juniper Community

Knowledge Base

Search our Knowledge Base sites to find answers to your questions.

Ask All Knowledge Base Sites All Knowledge Base Sites JunosE Defect (KA)Knowledge BaseSecurity AdvisoriesTechnical BulletinsTechnotes Sign in to display secure content and recently viewed articles

2019-07 Security Bulletin: Junos OS: Insufficient validation of environment variables in telnet client may lead to stack-based buffer overflow (CVE-2019-0053)

0

0

Article ID: JSA10947 SECURITY_ADVISORIES Last Updated: 10 Jul 2019Version: 1.0
Product Affected:
This issue affects all products and platforms running Junos OS.
Problem:

Insufficient validation of environment variables in the telnet client supplied in Junos OS can lead to stack-based buffer overflows, which can be exploited to bypass veriexec restrictions on Junos OS. A stack-based overflow is present in the handling of environment variables when connecting via the telnet client to remote telnet servers.

This issue only affects the telnet client — accessible from the CLI or shell — in Junos OS. Inbound telnet services are not affected by this issue.

This issue affects Juniper Networks Junos OS:

  • 12.3 versions prior to 12.3R12-S13;
  • 12.3X48 versions prior to 12.3X48-D80;
  • 14.1X53 versions prior to 14.1X53-D130, 14.1X53-D49;
  • 15.1 versions prior to 15.1F6-S12, 15.1R7-S4;
  • 15.1X49 versions prior to 15.1X49-D170;
  • 15.1X53 versions prior to 15.1X53-D237, 15.1X53-D496, 15.1X53-D591, 15.1X53-D69;
  • 16.1 versions prior to 16.1R3-S11, 16.1R7-S4;
  • 16.2 versions prior to 16.2R2-S9;
  • 17.1 versions prior to 17.1R3;
  • 17.2 versions prior to 17.2R1-S8, 17.2R2-S7, 17.2R3-S1;
  • 17.3 versions prior to 17.3R3-S4;
  • 17.4 versions prior to 17.4R1-S6, 17.4R2-S3, 17.4R3;
  • 18.1 versions prior to 18.1R2-S4, 18.1R3-S3;
  • 18.2 versions prior to 18.2R1-S5, 18.2R2-S2, 18.2R3;
  • 18.2X75 versions prior to 18.2X75-D40;
  • 18.3 versions prior to 18.3R1-S3, 18.3R2;
  • 18.4 versions prior to 18.4R1-S2, 18.4R2.


Juniper SIRT is not aware of any malicious exploitation of this vulnerability.

This issue was discovered during external security research.

This issue has been assigned CVE-2019-0053.
 

Solution:

The following software releases have been updated to resolve this specific issue: 12.3R12-S13, 12.3X48-D80, 12.3X48-D85, 14.1X53-D130, 14.1X53-D49, 15.1F6-S12, 15.1R7-S4, 15.1X49-D170, 15.1X53-D237, 15.1X53-D496, 15.1X53-D591, 15.1X53-D69, 16.1R3-S11, 16.1R7-S4, 16.2R2-S9, 17.1R3, 17.2R1-S8, 17.2R2-S7, 17.2R3-S1, 17.3R3-S4, 17.4R1-S6, 17.4R2-S3, 17.4R3, 18.1R2-S4, 18.1R3-S3, 18.2R1-S5, 18.2R2-S2, 18.2R3, 18.2X75-D40, 18.3R1-S3, 18.3R2, 18.4R1-S2, 18.4R2, 19.1R1, and all subsequent releases.

This issue is being tracked as PR 1409847 which is visible on the Customer Support website.

Note: Juniper SIRT's policy is not to evaluate releases which are beyond End of Engineering (EOE) or End of Life (EOL).
 

Workaround:

Since this issue is specific to outbound telnet connections to a malicious host from the local telnet client, mitigation includes:

  • limiting access to the Junos CLI and shell from only from trusted administrators
  • blocking outbound telnet connections via a stateless firewall filter
  • denying access to the 'telnet' command and the Junos shell
Implementation:
Software Releases, patches and updates are available at https://www.juniper.net/support/downloads/.
 
Modification History:
  • ‚Äč2019-07-10: Initial Publication
    
    
CVSS Score:
7.8 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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."
Acknowledgements:
The Juniper SIRT would like to would like to acknowledge and thank Matthew Hickey, Hacker House (https://hacker.house/), who reported this issue on November 12, 2018.
 

Related Links

Affected Products Browse the Knowledge Base for more articles related to these product categories. Select a category to begin.

Getting Up and Running with Junos

Getting Up and Running with Junos Security Alerts and Vulnerabilities Product Alerts and Software Release Notices Problem Report (PR) Search Tool EOL Notices and Bulletins JTAC User Guide Customer Care User Guide Pathfinder SRX High Availability Configurator SRX VPN Configurator Training Courses and Videos End User Licence Agreement Global Search