2019-04 Security Bulletin: Junos OS: Specially crafted packets sent to port 111 on any interface triggers responses from the management interface (CVE-2019-0040)

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Product Affected:
This issue affects Junos OS 15.1, 15.1X53, 16.1, 16.2, 17.1, 17.2, 17.3, 17.4.
Problem:

On Junos OS, rpcbind should only be listening to port 111 on the internal routing instance (IRI). External packets destined to port 111 should be dropped. Due to an information leak vulnerability, responses were being generated from the source address of the management interface (e.g. fxp0) thus disclosing internal addressing and existence of the management interface itself. A high rate of crafted packets destined to port 111 may also lead to a partial Denial of Service (DoS).

Note: Systems with fxp0 disabled or unconfigured are not vulnerable to this issue.

This issue only affects Junos OS releases based on FreeBSD 10 or higher (typically Junos OS 15.1+). Administrators can confirm whether systems are running a version of Junos OS based on FreeBSD 10 or higher by typing:

user@junos> show version | match kernel 
JUNOS OS Kernel 64-bit [20181214.223829_fbsd-builder_stable_10]

Affected releases are Juniper Networks Junos OS:

  • 15.1 versions prior to 15.1F6-S12, 15.1R7-S4;
  • 15.1X53 versions prior to 15.1X53-D236;
  • 16.1 versions prior to 16.1R7-S1;
  • 16.2 versions prior to 16.2R2-S9;
  • 17.1 versions prior to 17.1R3;
  • 17.2 versions prior to 17.2R1-S8;
  • 17.3 versions prior to 17.3R2;
  • 17.4 versions prior to 17.4R1-S1, 17.4R1-S7, 17.4R2.

This issue does not affect Junos OS releases prior to 15.1.

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

This issue was seen during production usage.

This issue has been assigned CVE-2019-0040.
 

Solution:

The following software releases have been updated to resolve this specific issue: Junos OS 15.1F6-S12, 15.1R7-S4, 15.1X53-D236, 16.1R7-S1, 16.2R2-S9, 17.1R3, 17.2R1-S8, 17.2R3, 17.3R2, 17.4R1-S1, 17.4R1-S7, 17.4R2, 18.1R1, 18.1X75-D10, and all subsequent releases.

This issue is being tracked as PR 1296262 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:
  • Use access lists or firewall filters to limit access to port 111 on the device.
     
  • Disable the management interface (fxp0) if it is not needed in a production environment.
     
  • If neither MS MICs nor MS MPCs are deployed, an additional option is to disable rpcbind via the configuration command:
     
set system processes rpcbind-service disable
 
Implementation:
Software Releases, patches and updates are available at https://www.juniper.net/support/downloads/.
 
Modification History:
  • 2019-04-10: Initial Publication
  • 2019-04-12: Confirmed that SRX Series products do not use rpcbind and are not affected by this issue
     
Related Links:
CVSS Score:
6.5 (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L)
Severity Level:
Medium
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."