CVE-2018-12563 in Lava
Summary
by MITRE
An issue was discovered in Linaro LAVA before 2018.5.post1. Because of support for file: URLs, a user can force lava-server-gunicorn to download any file from the filesystem if it's readable by lavaserver and valid yaml.
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Analysis
by VulDB Data Team • 02/20/2020
The vulnerability identified as CVE-2018-12563 affects Linaro LAVA (Linaro Automated Validation Architecture) versions prior to 2018.5.post1, representing a critical security flaw that enables unauthorized file access through improper handling of file:// URLs. This issue stems from the system's inadequate validation of URL schemes during configuration processing, creating a path traversal vulnerability that allows malicious users to exploit the system's YAML parsing capabilities. The vulnerability specifically targets the lava-server-gunicorn component, which serves as the primary web server interface for the LAVA validation framework.
The technical flaw manifests when the system processes configuration files that contain file:// URLs, allowing attackers to specify arbitrary file paths that the server can access if those files are readable by the lavaserver user account. This creates a directory traversal condition where the YAML parser inadvertently treats file:// URLs as legitimate file references, bypassing normal access controls and potentially exposing sensitive system files including configuration data, credentials, or other restricted resources. The vulnerability operates at the application layer and specifically relates to improper input validation and insecure deserialization practices.
The operational impact of this vulnerability is significant as it enables attackers with minimal privileges to potentially access sensitive data that should remain protected within the system's filesystem. An attacker could leverage this flaw to extract configuration files, database connection strings, API keys, or other confidential information that might be stored in readable files accessible to the lavaserver process. This access could lead to further exploitation opportunities, including privilege escalation or lateral movement within the network infrastructure that relies on LAVA for automated testing and validation processes. The vulnerability affects systems where LAVA is used for continuous integration testing, device validation, or automated quality assurance processes.
Mitigation strategies for CVE-2018-12563 involve immediate upgrading to LAVA version 2018.5.post1 or later, which includes proper URL scheme validation and sanitization. Organizations should also implement network segmentation to limit access to LAVA servers, restrict file permissions for the lavaserver user account, and employ input validation controls to prevent processing of file:// URLs in configuration files. The vulnerability aligns with CWE-22 (Improper Limitation of a Pathname to a Restricted Directory) and CWE-776 (Improper Restriction of XML External Entity Reference) categories, and represents a technique that could be categorized under ATT&CK tactic TA0006 (Credential Access) and technique T1552.001 (Unsecured Credentials). System administrators should also consider implementing web application firewalls and monitoring for suspicious URL patterns in system logs to detect potential exploitation attempts.