CVE-2017-18086 in Confluence Server
Summary
by MITRE
Various resources in Atlassian Confluence Server before version 6.4.2 allow remote attackers to inject arbitrary HTML or JavaScript via a cross site scripting (XSS) vulnerability in the issuesURL parameter.
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Analysis
by VulDB Data Team • 01/01/2020
The vulnerability identified as CVE-2017-18086 represents a critical cross site scripting flaw in Atlassian Confluence Server versions prior to 6.4.2. This vulnerability specifically targets the issuesURL parameter within various resources of the web application, creating an attack vector that allows remote malicious actors to inject arbitrary HTML or JavaScript code into the application's response. The flaw stems from inadequate input validation and output encoding mechanisms that fail to properly sanitize user-supplied data before rendering it within the web interface. This type of vulnerability falls under the Common Weakness Enumeration category CWE-79, which specifically addresses Cross-Site Scripting flaws where improper validation of input allows attackers to inject malicious scripts into web pages viewed by other users.
The operational impact of this vulnerability extends beyond simple script injection, as it can enable attackers to execute arbitrary code within the context of a victim's browser session. Attackers can leverage this weakness to perform session hijacking, steal sensitive cookies, redirect users to malicious websites, or even execute persistent attacks through stored XSS mechanisms. The vulnerability affects the core functionality of Confluence Server by compromising the integrity of user interactions and potentially allowing unauthorized access to confidential documentation and collaboration data. Given that Confluence Server is widely used for enterprise documentation and knowledge management, the potential for widespread impact is significant, particularly in environments where sensitive business information is stored and shared.
The exploitation of this vulnerability requires minimal privileges as it operates entirely through web-based attack vectors, making it particularly dangerous for organizations with extensive Confluence deployments. Remote attackers can craft malicious URLs containing the vulnerable issuesURL parameter and deliver them through various social engineering techniques such as phishing emails, compromised websites, or malicious links in collaboration tools. The attack surface is broad since the vulnerability affects multiple resources within the application, increasing the likelihood of successful exploitation. Organizations implementing security controls such as Content Security Policy headers and proper input validation can mitigate some of the risks, but the most effective defense involves applying the vendor-provided security patches and updates that address the root cause of the XSS vulnerability.
Security practitioners should consider this vulnerability in the context of the MITRE ATT&CK framework, particularly under the techniques related to credential access and execution through web-based attacks. The vulnerability represents a significant risk to enterprise security postures, as it can serve as a foothold for more sophisticated attacks targeting the broader network infrastructure. Organizations should prioritize patch management processes to ensure timely deployment of the Confluence Server 6.4.2 update or higher versions that contain the necessary fixes for this XSS vulnerability. Additionally, implementing web application firewalls and regular security assessments can provide additional layers of protection against exploitation attempts targeting this and similar vulnerabilities in collaborative platforms.