CVE-2020-15092 in TimelineJS
Summary
by MITRE
In TimelineJS before version 3.7.0, some user data renders as HTML. An attacker could implement an XSS exploit with maliciously crafted content in a number of data fields. This risk is present whether the source data for the timeline is stored on Google Sheets or in a JSON configuration file. Most TimelineJS users configure their timeline with a Google Sheets document. Those users are exposed to this vulnerability if they grant write access to the document to a malicious inside attacker, if the access of a trusted user is compromised, or if they grant public write access to the document. Some TimelineJS users configure their timeline with a JSON document. Those users are exposed to this vulnerability if they grant write access to the document to a malicious inside attacker, if the access of a trusted user is compromised, or if write access to the system hosting that document is otherwise compromised. Version 3.7.0 of TimelineJS addresses this in two ways. For content which is intended to support limited HTML markup for styling and linking, that content is "sanitized" before being added to the DOM. For content intended for simple text display, all markup is stripped. Very few users of TimelineJS actually install the TimelineJS code on their server. Most users publish a timeline using a URL hosted on systems we control. The fix for this issue is published to our system such that **those users will automatically begin using the new code**. The only exception would be users who have deliberately edited the embed URL to "pin" their timeline to an earlier version of the code. Some users of TimelineJS use it as a part of a wordpress plugin (knight-lab-timelinejs). Version 3.7.0.0 of that plugin and newer integrate the updated code. Users are encouraged to update the plugin rather than manually update the embedded version of TimelineJS.
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Analysis
by VulDB Data Team • 10/29/2020
The vulnerability described in CVE-2020-15092 represents a cross-site scripting vulnerability within TimelineJS version 3.6.9 and earlier, which allows attackers to inject malicious scripts through user-controllable data fields. This flaw exists in the rendering process where user-provided content is directly inserted into the document object model without proper sanitization, creating an environment where attackers can execute arbitrary JavaScript code in the context of other users' browsers. The vulnerability specifically affects the TimelineJS library that enables users to create interactive timelines, with the risk manifesting whether data is sourced from Google Sheets or JSON configuration files. The issue stems from the library's handling of HTML content in various data fields, where the application fails to properly sanitize user input before rendering it as HTML in the browser.
The technical implementation of this vulnerability involves the application's failure to implement proper input validation and output encoding mechanisms for user-supplied content. According to CWE-79, this vulnerability maps directly to Cross-Site Scripting (XSS) flaws that occur when untrusted data is sent to a web browser without proper sanitization or encoding. The attack vectors are particularly concerning because they can be exploited through multiple pathways including compromised credentials, insider threats, or misconfigured access controls. When users configure timelines using Google Sheets, attackers with write permissions can inject malicious content that executes when other users view the timeline. Similarly, when JSON configuration files are used, attackers with access to modify these files can introduce malicious payloads. The vulnerability is particularly dangerous because it operates at the presentation layer where user data is rendered, making it difficult to distinguish between legitimate content and malicious code.
The operational impact of this vulnerability extends beyond simple script execution to potentially enable more sophisticated attacks including session hijacking, data exfiltration, and privilege escalation within the affected user base. Attackers could leverage this vulnerability to steal cookies, access sensitive information, or perform actions on behalf of authenticated users. The attack surface is broad since most TimelineJS users rely on Google Sheets for data configuration, making the system vulnerable to insider threats or compromised accounts. Additionally, the vulnerability affects WordPress users who utilize the knight-lab-timelinejs plugin, creating a secondary attack vector through the WordPress ecosystem. The exploitation requires minimal technical skill and can be automated, making it particularly dangerous for widespread deployment. The vulnerability affects the core functionality of TimelineJS, which is designed to display temporal information, but the malicious code execution compromises the integrity and confidentiality of the user environment.
The remediation implemented in TimelineJS version 3.7.0 addresses this vulnerability through comprehensive input sanitization and output encoding strategies. The fix employs two distinct approaches: first, content that is intended to support limited HTML markup for styling and linking is now sanitized before insertion into the DOM, ensuring that only safe HTML elements and attributes are preserved. Second, content designated for simple text display undergoes complete markup stripping to prevent any possibility of script injection. This dual approach aligns with security best practices for preventing XSS vulnerabilities by implementing both input validation and output encoding. The fix is automatically deployed to users who access TimelineJS through the vendor-controlled hosting systems, which represents the majority of users. However, users who have manually pinned their embed URLs to older versions remain vulnerable, requiring proactive updates to maintain protection. The security measures implemented are consistent with ATT&CK framework's T1203 technique for exploitation of web application vulnerabilities, specifically targeting the execution of malicious code through web-based interfaces. Organizations using TimelineJS should ensure they are running version 3.7.0 or later and update their WordPress plugins accordingly to prevent exploitation of this vulnerability. The fix demonstrates a robust approach to web application security by addressing the root cause of the vulnerability through proper input handling rather than attempting to patch symptoms after exploitation.