CVE-2021-0219 in Junos
Summary
by MITRE • 01/16/2021
A command injection vulnerability in install package validation subsystem of Juniper Networks Junos OS that may allow a locally authenticated attacker with privileges to execute commands with root privilege. To validate a package in Junos before installation, an administrator executes the command 'request system software add validate-on-host' via the CLI. An attacker with access to this CLI command may be able to exploit this vulnerability. This issue affects Juniper Networks Junos OS: all versions prior to 17.3R3-S10; 17.4 versions prior to 17.4R2-S12, 17.4R3-S3; 18.1 versions prior to 18.1R3-S11; 18.2 versions prior to 18.2R2-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, 19.1R2-S2, 19.1R3-S3; 19.2 versions prior to 19.2R3-S1; 19.3 versions prior to 19.3R2-S5, 19.3R3-S1; 19.4 versions prior to 19.4R2-S2, 19.4R3-S1; 20.1 versions prior to 20.1R2; 20.2 versions prior to 20.2R1-S2, 20.2R2; 20.3 versions prior to 20.3R1-S1, 20.3R2.
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Analysis
by VulDB Data Team • 02/15/2021
This command injection vulnerability exists within the package validation subsystem of Juniper Networks Junos OS, representing a critical security flaw that enables locally authenticated attackers to escalate privileges and execute arbitrary commands with root-level access. The vulnerability specifically impacts the 'request system software add validate-on-host' CLI command, which administrators use to validate software packages before installation. The flaw stems from inadequate input sanitization within the validation process, allowing maliciously crafted input to be interpreted and executed as system commands rather than being treated as benign data. This represents a classic command injection vulnerability that aligns with CWE-77 and follows patterns identified in the ATT&CK framework under T1059.001 for command and scripting interpreter and T1548.001 for abuse of privileges.
The technical implementation of this vulnerability allows an attacker with legitimate access to the CLI to manipulate the validation process by injecting command sequences that bypass normal input validation mechanisms. When the system processes the malformed input during package validation, it executes the injected commands with the highest available privileges, effectively providing a backdoor for privilege escalation. The affected versions span multiple major releases including 17.3 through 20.3, indicating this flaw has persisted across several years of development cycles and suggests inadequate security testing or code review processes during the software development lifecycle. The vulnerability's impact is particularly severe because it requires only local authentication access, meaning an attacker who has already gained administrative privileges can leverage this flaw to achieve full system compromise.
The operational implications of this vulnerability extend beyond simple privilege escalation, as it fundamentally undermines the integrity of the system's software validation process. Attackers can potentially install malicious software packages that appear legitimate during validation but contain harmful code, or they can execute arbitrary system commands to modify critical system files, disable security features, or establish persistent access. This vulnerability directly impacts the principle of least privilege and can lead to complete system compromise when combined with other attack vectors. Organizations running affected Junos OS versions face significant risk of data breaches, system infiltration, and potential denial of service attacks, as the attacker can manipulate the system's software management functions to achieve unauthorized access and control. The widespread affected versions also indicate that numerous enterprise networks may be exposed, making this a high-priority remediation target.
Mitigation strategies should focus on immediate patch deployment to the latest stable releases, as provided by Juniper Networks in their security advisories. Organizations should also implement additional access controls and monitoring around CLI usage, particularly for commands involving system software management. Network segmentation and privilege separation can help limit the impact if an attacker does gain access to the CLI. Regular security audits and input validation testing should be conducted to identify similar vulnerabilities in other system components. The remediation process should include thorough testing of patches in controlled environments before deployment to production systems to avoid potential service disruptions. Additionally, implementing automated monitoring for unusual CLI command patterns and command injection attempts can provide early detection capabilities for potential exploitation attempts.