DoS in dynamic filter implementation in Juniper Junos OS

1) Security features bypass

EUVDB-ID: #VU49557

Risk: Medium

CVSSv3.1: 5.1 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-0205

CWE-ID: CWE-254 - Security Features

Exploit availability: No

Description

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to an error in dynamic filter implementation, when the "Intrusion Detection Service" (IDS) feature is configured on Juniper Networks MX series with a dynamic firewall filter using IPv6 source or destination prefix. The filter may incorrectly match the prefix as /32, causing the filter to block unexpected traffic.

Mitigation

Install updates from vendor's website.

This issue affects Juniper Networks Junos OS:

• 17.3 versions prior to 17.3R3-S10 on MX Series;
• 17.4 versions prior to 17.4R3-S3 on MX Series;
• 18.1 versions prior to 18.1R3-S11 on MX Series;
• 18.2 versions prior to 18.2R3-S6 on MX Series;
• 18.3 versions prior to 18.3R3-S4 on MX Series;
• 18.4 versions prior to 18.4R3-S6 on MX Series;
• 19.1 versions prior to 19.1R2-S2, 19.1R3-S3 on MX Series;
• 19.2 versions prior to 19.2R3-S1 on MX Series;
• 19.3 versions prior to 19.3R2-S5, 19.3R3-S1 on MX Series;
• 19.4 versions prior to 19.4R3 on MX Series;
• 20.1 versions prior to 20.1R2 on MX Series;
• 20.2 versions prior to 20.2R2 on MX Series;

Vulnerable software versions

Juniper Junos OS: 17.3 - 20.3

External links

http://kb.juniper.net/InfoCenter/index?page=content&id=JSA11095&cat=SIRT_1&actp=LIST

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.