A vulnerability in BIND code, used in Juniper Networks Junos OS on SRX Series devices, which checks the validity of messages containing TSIG resource records can be exploited by an attacker to trigger an assertion failure in tsig.c, resulting in a Denial of Service (DoS).

Using a specially-crafted message, an attacker may potentially cause a BIND server to reach an inconsistent state if the attacker knows (or successfully guesses) the name of a TSIG key used by the server. Since BIND, by default, configures a local session key even on servers whose configuration does not otherwise make use of it, almost all current BIND servers are vulnerable. In vulnerable releases of BIND, the server is missing an assertion check in tsig.c to detect this inconsistent state, and would continue operating in an inconsistent state, with potentially harmful results.

This issue only affect SRX Series devices, which is the only platform that ships with BIND software. No other products or platforms are affected by this vulnerability.

This issue affects Juniper Networks Junos OS on SRX Series:

• 12.3X48 versions prior to 12.3X48-D105;
• 15.1X49 versions prior to 15.1X49-D230;
• 17.3 versions prior to 17.3R3-S10;
• 17.4 versions prior to 17.4R2-S12, 17.4R3-S4;
• 18.1 versions prior to 18.1R3-S12;
• 18.2 versions prior to 18.2R2-S8, 18.2R3-S6;
• 18.3 versions prior to 18.3R3-S4;
• 18.4 versions prior to 18.4R1-S8, 18.4R2-S7, 18.4R3-S6;
• 19.1 versions prior to 19.1R1-S6, 19.1R3-S3;
• 19.2 versions prior to 19.2R1-S6, 19.2R3;
• 19.3 versions prior to 19.3R2-S5, 19.3R3;
• 19.4 versions prior to 19.4R2-S2, 19.4R3;
• 20.1 versions prior to 20.1R2;
• 20.2 versions prior to 20.2R1-S2, 20.2R2.

An example of the configuration to enable DNS Proxy is shown below:

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-2020-8617 .
 

The following software releases have been updated to resolve this specific issue: 12.3X48-D105, 15.1X49-D230, 17.3R3-S10, 17.4R2-S12, 17.4R3-S4, 18.1R3-S12, 18.2R2-S8, 18.2R3-S6, 18.3R3-S4, 18.4R1-S8, 18.4R2-S7, 18.4R3-S6, 19.1R1-S6, 19.1R3-S3, 19.2R1-S6, 19.2R3, 19.3R2-S5, 19.3R3, 19.4R2-S2, 19.4R3, 20.1R2, 20.2R1-S2, 20.2R2, 20.3R1, and all subsequent releases.

This issue is being tracked as  1512810 .
 

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

Disable DNS Proxy on SRX Series devices.
 

2021-01-13: Initial Publication.

• KB16613: Overview of the Juniper Networks SIRT Quarterly Security Bulletin Publication Process [juniper.net]
• KB16765: In which releases are vulnerabilities fixed? [juniper.net]
• KB16446: Common Vulnerability Scoring System (CVSS) and Juniper's Security Advisories [juniper.net]
• Report a Security Vulnerability - How to Contact the Juniper Networks Security Incident Response Team
• CVE-2020-8617 at cve.mitre.org