CVE-2017-11593 in Markdown Preview Plus Extension
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in the Markdown Preview Plus extension before 0.5.7 for Chrome allows remote attackers to inject arbitrary web script or HTML into some web applications via the upload and display of crafted text, markdown, or rst files that are designed to be viewed in the browser as plain text, but that will be converted to HTML without proper sanitization.
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Analysis
by VulDB Data Team • 12/13/2022
The CVE-2017-11593 vulnerability represents a critical cross-site scripting flaw within the Markdown Preview Plus browser extension for Chrome, affecting versions prior to 057. This vulnerability stems from insufficient input sanitization during the processing of markdown and other text formats that are converted to HTML for display. The flaw specifically manifests when users upload and view crafted text files that contain malicious script content, which the extension fails to properly sanitize before rendering in the browser environment.
The technical exploitation of this vulnerability occurs through the extension's handling of user-supplied content that undergoes conversion from plain text formats to HTML markup. When users view markdown, rst, or other text files through the extension, the application processes these files without adequate sanitization of potentially malicious content. This creates an environment where remote attackers can craft specially formatted files containing embedded javascript or html code that executes within the context of the user's browser session. The vulnerability is particularly dangerous because it leverages the trust relationship between the user and the browser extension, allowing malicious code execution without requiring user interaction beyond viewing the compromised file.
From an operational perspective, this vulnerability exposes users to significant security risks including session hijacking, credential theft, and data exfiltration. Attackers can leverage the XSS vector to steal cookies, manipulate browser sessions, or redirect users to malicious websites. The impact extends beyond individual user compromise as the vulnerability affects any user who relies on the Markdown Preview Plus extension for viewing text files, making it particularly concerning for developers, content creators, and organizations that frequently process markdown content. The vulnerability aligns with CWE-79, which specifically addresses cross-site scripting flaws in web applications, and represents a classic example of insecure input handling in client-side extensions.
The mitigation strategy for CVE-2017-11593 requires immediate upgrading to version 057 or later of the Markdown Preview Plus extension, which includes proper HTML sanitization of user input. Organizations should also implement additional security measures such as content security policies that restrict script execution and regular security audits of browser extensions. Users should be educated about the risks of viewing untrusted content through browser extensions and the importance of keeping software updated. From an ATT&CK framework perspective, this vulnerability maps to T1059.001 (Command and Scripting Interpreter: PowerShell) and T1566 (Phishing) as attackers can leverage the XSS to deliver malicious payloads and establish persistent access to user systems. The vulnerability also demonstrates the importance of input validation and output encoding practices as outlined in OWASP Top 10 and NIST cybersecurity guidelines, emphasizing that client-side applications must implement proper sanitization regardless of the perceived trust level of input sources.