CVE-2021-0231 in Junos OS
Summary
by MITRE • 04/23/2021
A path traversal vulnerability in the Juniper Networks SRX and vSRX Series may allow an authenticated J-web user to read sensitive system files. This issue affects Juniper Networks Junos OS on SRX and vSRX Series: 19.3 versions prior to 19.3R2-S6, 19.3R3-S1; 19.4 versions prior to 19.4R2-S4, 19.4R3; 20.1 versions prior to 20.1R1-S4, 20.1R2; 20.2 versions prior to 20.2R1-S3, 20.2R2; This issue does not affect Juniper Networks Junos OS versions prior to 19.3R1.
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Analysis
by VulDB Data Team • 04/29/2021
This vulnerability represents a critical path traversal flaw in Juniper Networks SRX and vSRX Series devices that operates through the J-web administrative interface. The issue stems from insufficient input validation when processing file paths within the web management interface, allowing authenticated users to manipulate directory traversal sequences and access files outside the intended directory structure. The vulnerability specifically impacts Junos OS versions that have not received the respective security patches, creating a persistent risk for organizations relying on these network security appliances. The flaw enables attackers with valid credentials to escalate their privileges and extract sensitive system information that should remain protected within the device's file system.
The technical implementation of this vulnerability involves the manipulation of file path parameters through the J-web interface, where the system fails to properly sanitize user-supplied input before processing file access requests. This allows an authenticated user to construct malicious paths using directory traversal sequences such as "../" or similar constructs that bypass normal access controls. The vulnerability operates at the application layer and specifically targets the web management interface components of the Junos OS, making it particularly dangerous for network administrators who rely on these interfaces for device management. According to CWE-22, this represents a classic path traversal vulnerability that allows attackers to access files and directories outside the intended scope of the application, potentially leading to unauthorized access to system configuration files, logs, and other sensitive data.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with the ability to extract critical system information that could be used for further exploitation. An attacker with valid J-web credentials could potentially access configuration files containing sensitive information such as encryption keys, user credentials, and network topology details that could be leveraged for lateral movement within the network. This vulnerability creates a significant risk for organizations that rely on SRX and vSRX devices for perimeter security, as it could allow an attacker to gain insights into the network infrastructure and potentially identify additional attack vectors. The affected versions span multiple release branches, indicating that this was a widespread issue that required coordinated patching across various Junos OS versions.
Organizations should prioritize immediate remediation by upgrading to the patched versions of Junos OS as specified in the CVE details, ensuring that all affected SRX and vSRX Series devices receive the appropriate security updates. Network administrators should implement strict access controls and monitor for unauthorized access attempts to the J-web interface, as the vulnerability requires only authenticated access to exploit. The implementation of network segmentation and privilege separation can help mitigate the impact of this vulnerability by limiting the potential damage from compromised administrative accounts. Additionally, organizations should conduct comprehensive vulnerability assessments to identify any other potential path traversal issues within their network infrastructure and ensure that all administrative interfaces properly validate user input. This vulnerability aligns with ATT&CK technique T1078 for valid accounts and T1005 for data from local system, highlighting the need for comprehensive security monitoring and access control measures to prevent exploitation.