CVE-2021-0218 in Junos
Summary
by MITRE • 01/16/2021
A command injection vulnerability in the license-check daemon of Juniper Networks Junos OS that may allow a locally authenticated attacker with low privileges to execute commands with root privilege. license-check is a daemon used to manage licenses in Junos OS. To update licenses, a user executes the command 'request system license update' via the CLI. An attacker with access to this CLI command may be able to exploit the vulnerability. This issue affects Juniper Networks Junos OS: 17.3 versions prior to 17.3R3-S9; 17.4 versions prior to 17.4R2-S12, 17.4R3-S3; 18.1 versions prior to 18.1R3-S11; 18.2 versions prior to 18.2R3-S6; 18.3 versions prior to 18.3R3-S4; 18.4 versions prior to 18.4R3-S6; 19.1 versions prior to 19.1R1-S6, 19.1R2-S2, 19.1R3-S3; 19.2 versions prior to 19.2R3-S1; 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 20.1R1-S4, 20.1R2; 20.2 versions prior to 20.2R1-S2, 20.2R2.
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Analysis
by VulDB Data Team • 02/15/2021
This command injection vulnerability in Juniper Networks Junos OS license-check daemon represents a critical privilege escalation flaw that allows locally authenticated users with minimal privileges to execute arbitrary commands with root-level permissions. The vulnerability specifically resides within the license-check daemon component responsible for managing software licenses in the Junos operating system, making it a particularly dangerous weakness given the daemon's privileged position within the system architecture. The attack vector involves exploitation of the 'request system license update' command through the command-line interface, where an attacker with access to this functionality can inject malicious commands that bypass normal security controls.
The technical implementation of this vulnerability stems from improper input validation within the license-check daemon's processing of license update requests. When users execute the license update command, the daemon fails to properly sanitize or validate input parameters, creating opportunities for command injection attacks. This weakness enables attackers to append malicious commands that get executed within the context of the privileged daemon process, effectively allowing elevation from user privileges to root access. The flaw operates at the application layer and specifically affects the daemon's handling of license-related data processing, making it particularly challenging to detect and prevent through standard network security measures.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it provides attackers with complete control over affected network devices. Once exploited, the vulnerability enables attackers to execute arbitrary code with root privileges, potentially allowing them to modify system configurations, install malicious software, exfiltrate sensitive data, or establish persistent access to network infrastructure. This represents a significant risk for organizations relying on Juniper networking equipment, as compromised devices could serve as entry points for broader network infiltration or as command and control nodes for distributed attacks. The vulnerability affects multiple Junos OS versions across several release branches, indicating it was likely present for an extended period and potentially exploited in the wild before discovery.
Organizations should prioritize immediate patching of affected systems according to Juniper's security advisories and implement additional mitigations including network segmentation, privileged access management controls, and enhanced monitoring of license update activities. The vulnerability aligns with CWE-77 and CWE-88 categories related to command injection, and maps to ATT&CK techniques such as privilege escalation through command execution and persistence mechanisms. Security teams should monitor for unusual license update activities, implement strict access controls for CLI commands, and consider network-based detection measures to identify potential exploitation attempts. The affected versions span multiple major releases, emphasizing the need for comprehensive vulnerability management programs that include regular security assessments and prompt patch deployment across all network infrastructure components.