CVE-2020-1669 in Junos
Summary
by MITRE • 10/17/2020
The Juniper Device Manager (JDM) container, used by the disaggregated Junos OS architecture on Juniper Networks NFX350 Series devices, stores password hashes in the world-readable file /etc/passwd. This is not a security best current practice as it can allow an attacker with access to the local filesystem the ability to brute-force decrypt password hashes stored on the system. This issue affects Juniper Networks Junos OS on NFX350: 19.4 versions prior to 19.4R3; 20.1 versions prior to 20.1R1-S4, 20.1R2.
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Analysis
by VulDB Data Team • 11/20/2020
The vulnerability described in CVE-2020-1669 represents a critical configuration flaw within the Juniper Device Manager architecture that undermines fundamental security principles of credential storage. This issue specifically impacts the disaggregated Junos OS implementation on NFX350 Series devices where the JDM container operates with insufficient access controls on its password database file. The flaw manifests as a direct violation of security best practices by storing password hashes in a world-readable file located at /etc/passwd, which effectively removes any meaningful access restrictions that should normally protect sensitive authentication data. This configuration error creates an immediate and severe security risk for organizations relying on these network devices.
The technical implementation of this vulnerability stems from improper file system permissions within the containerized JDM environment. When password hashes are stored in a world-readable file, any local user or process with filesystem access can directly read and extract these credentials without requiring additional authentication mechanisms. This represents a classic case of inadequate privilege separation and improper secure coding practices that violates fundamental security principles. The vulnerability affects specific software versions including Junos OS 19.4 releases prior to 19.4R3 and 20.1 releases prior to 20.1R1-S4 and 20.1R2, indicating this was a persistent issue across multiple release streams that required specific patches to address.
The operational impact of this vulnerability extends far beyond simple credential exposure, creating a pathway for attackers to perform offline password cracking attacks and potentially escalate privileges within the network infrastructure. An attacker with local filesystem access can immediately begin brute-forcing the stored password hashes, potentially gaining unauthorized access to administrative accounts and network resources. This vulnerability directly maps to CWE-732: Incorrect Permission Assignment for Critical Resource, which specifically addresses the scenario where critical system resources are assigned incorrect permissions that allow unauthorized access. The implications are particularly severe for network infrastructure devices where administrative access can provide complete control over network traffic, device configuration, and potentially sensitive data flows.
From an attack perspective, this vulnerability aligns with techniques documented in the MITRE ATT&CK framework under the T1003.001 sub-technique for Credential Dumping, where attackers target password hashes stored in system files. The vulnerability creates a direct attack surface that allows threat actors to bypass traditional network-based authentication mechanisms by leveraging local filesystem access. Organizations utilizing affected NFX350 Series devices face significant risk of privilege escalation and unauthorized network access, particularly in environments where physical or local access controls are insufficient. The remediation process requires immediate patching of affected software versions and implementation of proper file system permissions to ensure that sensitive credential data is not exposed to unauthorized users or processes. Security teams must also conduct comprehensive audits of all similar containerized applications to identify and remediate comparable misconfigurations that could create similar attack vectors within their network infrastructure.