CVE-2021-0244
Vulnérabilité élevée dans Junos OS (Juniper Networks)
Description
A signal handler race condition exists in the Layer 2 Address Learning Daemon (L2ALD) of Juniper Networks Junos OS due to the absence of a specific protection mechanism to avoid a race condition which may allow an attacker to bypass the storm-control feature on devices. This issue is a corner case and only occurs during specific actions taken by an administrator of a device under certain specifics actions which triggers the event. The event occurs less frequently on devices which are not configured with Virtual Chassis configurations, and more frequently on devices configured in Virtual Chassis configurations. This issue is not specific to any particular Junos OS platform. An Indicator of Compromise (IoC) may be seen by reviewing log files for the following error message seen by executing the following show statement: show log messages | grep storm Result to look for: /kernel: GENCFG: op 58 (Storm Control Blob) failed; err 1 (Unknown) This issue affects: Juniper Networks Junos OS: 14.1X53 versions prior to 14.1X53-D49 on EX Series; 15.1 versions prior to 15.1R7-S6; 15.1X49 versions prior to 15.1X49-D191, 15.1X49-D200 on SRX Series; 16.1 versions prior to 16.1R7-S7; 16.2 versions prior to 16.2R2-S11, 16.2R3; 17.1 versions prior to 17.1R2-S11, 17.1R3; 17.2 versions prior to 17.2R2-S8, 17.2R3-S3; 17.3 versions prior to 17.3R2-S5, 17.3R3-S7; 17.4 versions prior to 17.4R2-S9, 17.4R3; 18.1 versions prior to 18.1R3-S5; 18.2 versions prior to 18.2R2-S6, 18.2R3; 18.3 versions prior to 18.3R1-S7, 18.3R2-S3, 18.3R3; 18.4 versions prior to 18.4R1-S5, 18.4R2; 19.1 versions prior to 19.1R1-S4, 19.1R2.
Gravité et risque d'exploitation
CVE-2021-0244 obtient un score CVSS de 7.4/10, soit une gravité élevée. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.64 %, ce qui la place devant 49.5 % des CVE référencées.
Que faire ?
- Vérifiez si Junos OS (versions 16.1, <17.1R2-S11, 17.1R3, 15.1X49, <18.2R2-S6, 18.2R3, <18.4R1-S5, 18.4R2, 14.1X53, 16.2, 18.2, <17.4R2-S9, 17.4R3, <15.1X49-D191, 15.1X49-D200, <15.1R7-S6, 18.3, <17.2R2-S8, 17.2R3-S3, 19.1, 15.1, <14.1X53-D49, 17.1, <18.1R3-S5, 18.1, 17.4, 18.4, 17.3, <16.2R2-S11, 16.2R3, <16.1R7-S7, <17.3R2-S5, 17.3R3-S7, <18.3R1-S7, 18.3R2-S3, 18.3R3, <19.1R1-S4, 19.1R2, 17.2) est présent sur votre parc.
- Appliquez le correctif ou la version corrigée indiqués dans les références de l'éditeur.
- À défaut de correctif, limitez l'exposition (filtrage réseau, désactivation du composant).
- Automatisez la détection : les agents CVE Heimdall (gratuits, open source) corrèlent l'inventaire de vos serveurs avec la base CVE.