CVE-2022-22156 in Junos OS
Summary
by MITRE • 01/19/2022
An Improper Certificate Validation weakness in the Juniper Networks Junos OS allows an attacker to perform Person-in-the-Middle (PitM) attacks when a system script is fetched from a remote source at a specified HTTPS URL, which may compromise the integrity and confidentiality of the device. The following command can be executed by an administrator via the CLI to refresh a script from a remote location, which is affected from this vulnerability: >request system scripts refresh-from (commit | event | extension-service | op | snmp) file filename url This issue affects: Juniper Networks Junos OS All versions prior to 18.4R2-S9, 18.4R3-S9; 19.1 versions prior to 19.1R2-S3, 19.1R3-S7; 19.2 versions prior to 19.2R1-S7, 19.2R3-S3; 19.3 versions prior to 19.3R3-S4; 19.4 versions prior to 19.4R3-S7; 20.1 versions prior to 20.1R2-S2, 20.1R3; 20.2 versions prior to 20.2R3; 20.3 versions prior to 20.3R2-S1, 20.3R3; 20.4 versions prior to 20.4R2; 21.1 versions prior to 21.1R1-S1, 21.1R2.
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Analysis
by VulDB Data Team • 01/20/2022
The vulnerability described in CVE-2022-22156 represents a critical weakness in the Juniper Networks Junos OS that undermines the security of certificate validation mechanisms during remote script fetching operations. This issue specifically impacts the system's ability to verify the authenticity and integrity of scripts retrieved from remote HTTPS sources, creating a significant attack surface for man-in-the-middle adversaries. The flaw exists within the certificate validation process that occurs when administrators execute the command request system scripts refresh-from, which allows scripts to be downloaded and executed from specified HTTPS URLs. This command interface supports multiple script types including commit, event, extension-service, op, and snmp, each presenting unique risks when operating with compromised certificate validation.
The technical implementation of this vulnerability stems from inadequate certificate verification procedures within the Junos OS HTTPS client implementation. When the system fetches scripts from remote locations, it fails to properly validate SSL/TLS certificates against established trust anchors, allowing attackers to present fraudulent certificates that would otherwise be rejected by proper validation mechanisms. This weakness enables attackers to intercept and modify script content during transmission, potentially injecting malicious code that could execute with administrative privileges on the target device. The vulnerability manifests specifically during the script refresh operations where certificate validation should occur but does not, creating a window of opportunity for attackers to compromise the device's integrity and confidentiality.
The operational impact of this vulnerability extends beyond simple certificate validation failure, as it directly enables privilege escalation and persistent access to affected Juniper devices. Attackers can leverage this weakness to execute arbitrary code on network infrastructure devices, potentially compromising entire network segments that rely on Juniper routing and switching equipment. The attack vector requires minimal privileges since the vulnerability affects administrative functions that are typically accessible to authorized users. This creates a particularly dangerous scenario where legitimate administrative activities become potential attack vectors, making detection and prevention more challenging. The vulnerability affects a broad range of Junos OS versions, spanning multiple release branches from 18.4 through 21.1, indicating a widespread exposure across Juniper's product line.
Mitigation strategies for CVE-2022-22156 should prioritize immediate implementation of the vendor-provided security patches that address the certificate validation weakness in affected Junos OS versions. Organizations should also implement network monitoring to detect unauthorized script refresh operations and establish strict access controls for administrative functions. The security community has classified this vulnerability according to CWE-295, which specifically addresses "Improper Certificate Validation," aligning with the ATT&CK framework's technique T1566 for "Phishing" and T1071 for "Application Layer Protocol" where the attack occurs through compromised script delivery. Network segmentation and firewall rules should be configured to restrict outbound HTTPS connections from administrative interfaces, while also implementing certificate pinning where possible to further strengthen the security posture against this class of attack. Regular security assessments should verify that certificate validation mechanisms are properly functioning and that no unauthorized modifications have occurred to the script fetching infrastructure.