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Attack Tree Analysis for erusev/parsedown

Objective: Compromise application using Parsedown by exploiting weaknesses within Parsedown or its usage.

Attack Tree Visualization

  • Compromise Application Using Parsedown |- Exploit Parsedown Vulnerabilities [HIGH RISK PATH] | |- Cross-Site Scripting (XSS) [CRITICAL NODE] | | |- Inject Malicious Markdown Input [HIGH RISK PATH] | | | |- Via User Input Fields (e.g., comments, posts, profiles) [HIGH RISK PATH] | | | | |- Craft Markdown containing malicious HTML/JavaScript (e.g., <script>, <iframe>, <img> with onerror) [CRITICAL NODE] | | |- Parsedown Renders Malicious Markdown Unsafely [CRITICAL NODE] | | |- Browser Executes Malicious Script [CRITICAL NODE] | | | |- Malicious script executes in the context of the application's domain | | | | |- Steal session cookies [CRITICAL NODE] |- Denial of Service (DoS) | |- Craft Complex or Malicious Markdown Input [HIGH RISK PATH] | | |- Input with deeply nested structures (e.g., lists, quotes) [CRITICAL NODE] | |- Parsedown Resource Exhaustion [CRITICAL NODE] | |- Application Becomes Unavailable or Slow [CRITICAL NODE] |- Exploit Application Misuse of Parsedown | |- Improper Sanitization/Output Handling [CRITICAL NODE] | | |- Application fails to sanitize Parsedown output before rendering [HIGH RISK PATH] | | |- Vulnerable Output Rendered to User [CRITICAL NODE]

Attack Tree Path: Exploit Parsedown Vulnerabilities - Cross-Site Scripting (XSS) [HIGH RISK PATH & CRITICAL NODE]

  • Attack Vector: Injecting malicious Markdown input, specifically through user input fields (comments, posts, profiles).
    • Method: An attacker crafts Markdown content that includes embedded HTML or JavaScript code. This can be achieved by using HTML tags like <script>, <iframe>, or image tags with onerror attributes that execute JavaScript.
    • Critical Node: Craft Markdown containing malicious HTML/JavaScript: This is the core action of the attacker to prepare the XSS payload within Markdown.
    • Critical Node: Parsedown Renders Malicious Markdown Unsafely: If Parsedown fails to properly sanitize or escape the malicious HTML/JavaScript within the Markdown, it will be rendered as active code in the output.
    • Critical Node: Browser Executes Malicious Script: When the application displays the Parsedown output in a user's browser, the browser will execute the unsanitized JavaScript code.
    • Critical Node: Steal session cookies: A common objective of XSS attacks is to steal session cookies. Once an attacker has a user's session cookie, they can impersonate that user and gain unauthorized access to their account and data.

Attack Tree Path: Denial of Service (DoS) - Craft Complex or Malicious Markdown Input [HIGH RISK PATH]

  • Attack Vector: Crafting complex or malicious Markdown input designed to exhaust server resources during parsing.
    • Method: Attackers can create Markdown input with deeply nested structures (e.g., lists within lists within lists, or deeply nested quotes). Parsing such complex structures can be computationally expensive, leading to excessive CPU and memory consumption by the Parsedown library.
    • Critical Node: Input with deeply nested structures (e.g., lists, quotes): This type of input is specifically designed to trigger algorithmic complexity issues in the parser.
    • Critical Node: Parsedown Resource Exhaustion: When Parsedown processes the complex Markdown, it consumes excessive server resources (CPU, memory).
    • Critical Node: Application Becomes Unavailable or Slow: As server resources are exhausted, the application becomes slow, unresponsive, or even crashes, leading to a denial of service for legitimate users.

Attack Tree Path: Exploit Application Misuse of Parsedown - Improper Sanitization/Output Handling [HIGH RISK PATH & CRITICAL NODE]

  • Attack Vector: The application fails to properly sanitize or handle the output generated by Parsedown before rendering it to users.
    • Method: Even if Parsedown itself is secure in its parsing, the application might introduce vulnerabilities by incorrectly handling the output. This could involve:
      • Application fails to sanitize Parsedown output before rendering: The application directly outputs the HTML generated by Parsedown without any further sanitization or encoding.
      • Vulnerable Output Rendered to User: The unsanitized output, potentially containing malicious HTML/JavaScript from the original Markdown (if Parsedown or upstream sanitization failed), is rendered in the user's browser. This leads to XSS vulnerabilities.
    • Critical Node: Improper Sanitization/Output Handling: This represents a critical application-level flaw where security measures are insufficient or missing after Parsedown processing.
    • Critical Node: Vulnerable Output Rendered to User: This is the point where the application exposes the vulnerability to the user's browser, enabling XSS exploitation.