CVE-2019-3395 in Confluence Server
Summary
by MITRE
The WebDAV endpoint in Atlassian Confluence Server and Data Center before version 6.6.7 (the fixed version for 6.6.x), from version 6.7.0 before 6.8.5 (the fixed version for 6.8.x), and from version 6.9.0 before 6.9.3 (the fixed version for 6.9.x) allows remote attackers to send arbitrary HTTP and WebDAV requests from a Confluence Server or Data Center instance via Server-Side Request Forgery.
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Analysis
by VulDB Data Team • 05/24/2020
The vulnerability identified as CVE-2019-3395 represents a critical server-side request forgery flaw within Atlassian Confluence Server and Data Center platforms. This security weakness exists in the WebDAV endpoint implementation, which allows remote attackers to manipulate the application into making unauthorized HTTP and WebDAV requests to arbitrary destinations. The vulnerability affects multiple version ranges including 6.6.x before 6.6.7, 6.8.x before 6.8.5, and 6.9.x before 6.9.3, demonstrating the widespread nature of this flaw across the Confluence product line. The issue stems from insufficient validation of user-supplied input passed to the WebDAV functionality, creating a pathway for malicious actors to exploit the system's trust relationship with internal services.
The technical exploitation of this vulnerability enables attackers to perform unauthorized requests from the Confluence server to internal network resources that would normally be inaccessible from external networks. This occurs because the WebDAV endpoint accepts user input without proper sanitization or validation, allowing attackers to specify target URLs that the server will attempt to access on their behalf. The flaw essentially allows an attacker to use the Confluence server as a proxy for making requests to internal systems, potentially enabling information disclosure, service disruption, or further exploitation of internal network resources. This type of vulnerability is classified as CWE-918, which specifically addresses server-side request forgery vulnerabilities where applications fail to properly validate and sanitize user-provided URLs or endpoint specifications.
The operational impact of CVE-2019-3395 extends beyond simple data exfiltration, as it can facilitate more sophisticated attack vectors within corporate networks. An attacker who successfully exploits this vulnerability can potentially access internal services that are normally protected by firewalls or network segmentation, particularly if the Confluence server has access to sensitive internal systems. The attack surface becomes significantly larger when considering that Confluence servers often have network access to databases, application servers, or other critical infrastructure components. This vulnerability directly aligns with ATT&CK technique T1071.004 for application layer protocol usage and T1105 for remote file execution, as it allows for the exploitation of legitimate network services to gain unauthorized access to internal resources.
Organizations affected by this vulnerability should prioritize immediate remediation through the application of official patches released by Atlassian for the affected version ranges. The recommended mitigation strategy includes upgrading to Confluence versions 6.6.7, 6.8.5, or 6.9.3 respectively, depending on the current installation. Network segmentation and firewall rules should be reviewed to limit the network access of Confluence servers, particularly restricting outbound connections to only necessary internal services. Additional protective measures include implementing web application firewalls to monitor and filter WebDAV requests, enabling logging and monitoring of suspicious network activity, and conducting thorough network scans to identify any unauthorized access attempts. The vulnerability's classification as a server-side request forgery makes it particularly dangerous in environments where Confluence servers have access to sensitive internal resources, as it can effectively bypass traditional network security controls and provide attackers with a legitimate pathway to internal systems.