CVE-2017-18102 in atlassian-renderer
Summary
by MITRE
The wiki markup component of atlassian-renderer from version 8.0.0 before version 8.0.22 allows remote attackers to inject arbitrary HTML or JavaScript via a cross site scripting (XSS) vulnerability in nested wiki markup.
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Analysis
by VulDB Data Team • 01/25/2020
The vulnerability identified as CVE-2017-18102 resides within the atlassian-renderer wiki markup component, specifically affecting versions 8.0.0 through 8.0.21. This represents a critical cross site scripting flaw that enables remote attackers to execute malicious code within the context of affected applications. The vulnerability manifests when processing nested wiki markup structures, where improper input sanitization allows attackers to inject arbitrary HTML or JavaScript payloads that can be executed by other users interacting with the rendered content.
The technical flaw stems from insufficient validation and sanitization of user-supplied markup data during the rendering process. When nested wiki markup elements are processed, the renderer fails to adequately escape or filter special characters that could be interpreted as HTML or JavaScript code. This weakness creates an attack vector where malicious actors can craft wiki markup containing embedded scripts that execute in the browsers of other users who view the rendered content. The vulnerability specifically impacts the wiki rendering engine's handling of nested structures, where the parser does not properly distinguish between legitimate markup syntax and potentially harmful code injection attempts.
From an operational perspective, this vulnerability poses significant risks to organizations using Atlassian products such as Confluence and Jira, which rely on the atlassian-renderer component for wiki functionality. An attacker who can inject malicious code into wiki pages can potentially steal session cookies, redirect users to malicious sites, or execute arbitrary commands on victim machines. The impact extends beyond simple data theft to potential privilege escalation and lateral movement within network environments where these applications are deployed. The vulnerability affects both authenticated and unauthenticated users, making it particularly dangerous as it can be exploited without requiring valid credentials.
The security implications of CVE-2017-18102 align with CWE-79, which categorizes cross site scripting vulnerabilities as a fundamental weakness in input validation and output encoding. This vulnerability also maps to several ATT&CK techniques including T1059 for command and scripting interpreter usage, T1566 for spearphishing with malicious attachments, and T1547 for persistence mechanisms through web shells. Organizations should prioritize immediate patching to version 8.0.22 or later, as the fix addresses the core sanitization issues in the wiki markup processing engine. Additional mitigations include implementing content security policies, restricting user permissions for wiki editing, and monitoring for suspicious markup patterns in affected systems.
The vulnerability demonstrates the critical importance of proper input validation in web applications, particularly in components that process user-generated content. The flaw highlights the need for comprehensive security testing of rendering engines and the potential for seemingly benign functionality to become attack vectors. Organizations should conduct thorough vulnerability assessments of their Atlassian deployments and implement monitoring solutions to detect potential exploitation attempts. This vulnerability also underscores the necessity of maintaining up-to-date security patches and the risks associated with running outdated software versions in production environments.