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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2021.1328.2 JSA11147 - 2021-04 Security Bulletin: Junos OS: Remote code execution vulnerability in overlayd service 24 May 2021 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: Junos OS Publisher: Juniper Networks Operating System: Juniper Impact/Access: Execute Arbitrary Code/Commands -- Remote/Unauthenticated Denial of Service -- Remote/Unauthenticated Resolution: Patch/Upgrade CVE Names: CVE-2021-0254 Original Bulletin: http://kb.juniper.net/InfoCenter/index?page=content&id=JSA11147 Revision History: May 24 2021: Provide additional clarification on affected platforms, and how to determine if overlayd is running. April 21 2021: Initial Release - --------------------------BEGIN INCLUDED TEXT-------------------- 2021-04 Security Bulletin: Junos OS: Remote code execution vulnerability in overlayd service (CVE-2021-0254) Article ID : JSA11147 Last Updated: 21 May 2021 Version : 5.0 Product Affected: This issue affects Junos OS 15.1, 17.3, 17.4, 18.1, 18.2, 18.3, 18.4, 19.1, 19.2, 19.3, 19.4, 20.1, 20.2, 20.3. Problem: A buffer size validation vulnerability in the overlayd service of Juniper Networks Junos OS may allow an unauthenticated remote attacker to send specially crafted packets to the device, triggering a partial Denial of Service (DoS) condition, or leading to remote code execution (RCE). Continued receipt and processing of these packets will sustain the partial DoS. The overlayd daemon handles Overlay OAM packets, such as ping and traceroute, sent to the overlay. The service runs as root by default and listens for UDP connections on port 4789. This issue results from improper buffer size validation, which can lead to a buffer overflow. Unauthenticated attackers can send specially crafted packets to trigger this vulnerability, resulting in possible remote code execution. overlayd runs by default on MX Series, QFX Series, and certain ACX Series (e.g. ACX5445, but not the ACX5048) platforms. Platforms such as the SRX Series and PTX Series do not run overlayd and are therefore not vulnerable to this issue. Additionally, while some EX Series platforms do run overlayd, no model of EX Series switch has been shown to be exploitable to this vulnerability. To summarize, if overlayd is not running on a particular platform, the system is not vulnerable to this issue. Users can confirm the presence of the overlayd process by issuing the following command: user@junos> show system processes extensive | match overlay 2030 root 4 0 28984K 5004K kqread 0:00 0.00% overlayd This issue affects Juniper Networks Junos OS: o 15.1 versions prior to 15.1R7-S9; o 17.3 versions prior to 17.3R3-S11; o 17.4 versions prior to 17.4R2-S13, 17.4R3-S4; o 18.1 versions prior to 18.1R3-S12; o 18.2 versions prior to 18.2R2-S8, 18.2R3-S7; o 18.3 versions prior to 18.3R3-S4; o 18.4 versions prior to 18.4R1-S8, 18.4R2-S7, 18.4R3-S7; o 19.1 versions prior to 19.1R2-S2, 19.1R3-S4; o 19.2 versions prior to 19.2R1-S6, 19.2R3-S2; o 19.3 versions prior to 19.3R3-S1; o 19.4 versions prior to 19.4R2-S4, 19.4R3-S1; o 20.1 versions prior to 20.1R2-S1, 20.1R3; o 20.2 versions prior to 20.2R2, 20.2R2-S1, 20.2R3; o 20.3 versions prior to 20.3R1-S1. There is no minimum configuration required to be vulnerable to this issue. 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-2021-0254 . Solution: The following software releases have been updated to resolve this specific issue: Junos OS 15.1R7-S9, 17.3R3-S11, 17.4R2-S13, 17.4R3-S4, 18.1R3-S12, 18.2R2-S8, 18.2R3-S7, 18.3R3-S4, 18.4R1-S8, 18.4R2-S7, 18.4R3-S7, 19.1R2-S2, 19.1R3-S4, 19.2R1-S6, 19.2R3-S2, 19.3R3-S1, 19.4R2-S4, 19.4R3-S1, 20.1R2-S1, 20.1R3, 20.2R2, 20.2R2-S1, 20.2R3, 20.3R1-S1, 20.4R1, and all subsequent releases. This fix has also been proactively committed into other releases that might not be vulnerable to this issue. This issue is being tracked as 1548415 . Workaround: Two methods exist to mitigate this issue: 1. Limit the exploitable attack surface of critical infrastructure networking equipment by using access lists or firewall filters to limit access to the device via UDP only from trusted, administrative networks or hosts. 2. Disable Overlay OAM packet via the configuration command: ' set system processes overlay-ping-traceroute disable ' Implementation: Software releases or updates are available for download at https:// support.juniper.net/support/downloads/ Modification History: 2021-04-14: Initial Publication. 2021-04-20: Explicitly state that the SRX Series is not vulnerable. 2021-05-21: Provide additional clarification on affected platforms, and how to determine if overlayd is running. CVSS Score: 9.8 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H) Severity Level: Critical 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: Juniper SIRT would like to acknowledge and thank Hoang Thach Nguyen (d4rkn3ss) of STAR Labs for responsibly reporting this vulnerability. - --------------------------END INCLUDED TEXT-------------------- You have received this e-mail bulletin as a result of your organisation's registration with AusCERT. The mailing list you are subscribed to is maintained within your organisation, so if you do not wish to continue receiving these bulletins you should contact your local IT manager. If you do not know who that is, please send an email to auscert@auscert.org.au and we will forward your request to the appropriate person. NOTE: Third Party Rights This security bulletin is provided as a service to AusCERT's members. As AusCERT did not write the document quoted above, AusCERT has had no control over its content. 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