CVE-2021-0204 in Junos
Summary
by MITRE • 01/16/2021
A sensitive information disclosure vulnerability in delta-export configuration utility (dexp) of Juniper Networks Junos OS may allow a locally authenticated shell user the ability to create and read database files generated by the dexp utility, including password hashes of local users. Since dexp is shipped with setuid permissions enabled and is owned by the root user, this vulnerability may allow a local privileged user the ability to run dexp with root privileges and access sensitive information in the dexp database. This issue affects Juniper Networks Junos OS: 15.1 versions prior to 15.1R7-S8; 15.1X49 versions prior to 15.1X49-D230; 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; 18.2X75 versions prior to 18.2X75-D34; 18.3 versions prior to 18.3R3-S4; 18.4 versions prior to 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 19.2R1-S5, 19.2R3-S1; 19.3 versions prior to 19.3R2-S5, 19.3R3-S1; 19.4 versions prior to 19.4R1-S3, 19.4R2-S2, 19.4R3-S1; 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 • 02/14/2021
The vulnerability described in CVE-2021-0204 represents a critical sensitive information disclosure flaw within the delta-export configuration utility of Juniper Networks Junos OS operating systems. This issue stems from improper access controls and privilege escalation mechanisms within the dexp utility, which is designed to export configuration data from Junos devices. The vulnerability affects a wide range of Junos OS versions spanning multiple release branches from 15.1 through 20.2, indicating a long-standing security gap that has persisted across numerous system iterations. The affected versions demonstrate a pattern of insufficient privilege separation and inadequate file system access controls that could be exploited by malicious actors with local shell access.
The technical flaw manifests through the setuid permissions assigned to the dexp utility, which operates with root privileges due to its ownership by the root user account. This configuration creates a dangerous privilege escalation vector where a locally authenticated user can leverage the utility to access sensitive system information that should normally be restricted. The vulnerability specifically allows an attacker to create and read database files generated by dexp, which contain password hashes of local users on the system. This represents a direct breach of the principle of least privilege and demonstrates a failure in the operating system's access control mechanisms. The setuid bit, while intended to provide necessary elevated privileges for system administration tasks, has been improperly configured to allow unauthorized access to sensitive data structures.
The operational impact of this vulnerability extends far beyond simple information disclosure, as it provides attackers with access to password hashes that can be subjected to offline brute force attacks or rainbow table lookups. This access enables unauthorized users to potentially compromise local accounts and escalate their privileges further within the system. The vulnerability's presence in multiple Junos OS versions suggests that organizations running affected systems may be at risk of credential compromise across their network infrastructure. The implications are particularly severe given that the dexp utility is typically used for legitimate configuration management tasks, making the exploitation less likely to raise immediate alerts or suspicion. Network administrators face the challenge of identifying affected devices across their infrastructure while implementing remediation measures.
Security mitigations for this vulnerability should focus on immediate patch deployment across all affected Junos OS versions, as provided by Juniper Networks through their security advisories. Organizations must ensure that all systems running vulnerable versions are updated to the latest stable releases that contain the necessary security fixes. Additionally, system administrators should conduct comprehensive audits of setuid binaries and verify that no unauthorized modifications have been made to the dexp utility or related components. The implementation of principle of least privilege should be enforced by removing unnecessary setuid permissions where possible and ensuring that only required system utilities maintain elevated privileges. This vulnerability aligns with CWE-276, which addresses improper permissions for critical resources, and maps to ATT&CK technique T1003.001, focusing on credential dumping through the extraction of password hashes from system files. Organizations should also consider implementing network segmentation and monitoring controls to detect unauthorized access attempts to sensitive system utilities and configuration databases.