Skip to content

Latest commit

 

History

History
67 lines (45 loc) · 6.41 KB

attack-surface.md

File metadata and controls

67 lines (45 loc) · 6.41 KB

Attack Surface Analysis for asciinema/asciinema-player

Attack Surface: Cross-Site Scripting (XSS) via Malicious Recording Data (ANSI Escape Sequences and HTML Injection)

  • Description: Malicious JavaScript code is injected into an asciinema recording, exploiting insufficient sanitization of terminal output by asciinema-player. When a user views this recording, the script executes in their browser, within the context of the hosting website. This is primarily achieved through crafted ANSI escape sequences or direct HTML injection within the recording's terminal output.

  • asciinema-player Contribution to Attack Surface: asciinema-player is directly responsible for parsing and rendering the terminal output from the recording. If it fails to properly sanitize or encode this output before inserting it into the DOM, it creates a direct pathway for XSS attacks. Vulnerabilities arise from:

    • Inadequate ANSI Escape Sequence Handling: Maliciously crafted sequences can be interpreted to inject HTML or JavaScript.
    • Lack of HTML Encoding: Terminal output rendered as HTML without proper encoding allows direct HTML tag injection.

  • Example: A recording contains terminal output like: This is text <script>/* Malicious Script */ alert('XSS Vulnerability!');</script>. If asciinema-player renders this without escaping, the alert() will execute. Similarly, crafted ANSI escape codes could inject malicious HTML attributes or tags.

  • Impact:

    • Account Takeover: Stealing session cookies or credentials.
    • Data Theft: Exfiltrating sensitive information from the webpage.
    • Website Defacement: Modifying the website's appearance.
    • Malware Distribution: Redirecting users to malicious sites or initiating malware downloads.

  • Risk Severity: Critical

  • Mitigation Strategies:

    • Strict Output Sanitization and Encoding: Implement robust sanitization of all terminal output before DOM insertion.
      • HTML Entity Encoding: Escape HTML special characters in terminal output.
      • Secure ANSI Parsing: Use a well-vetted library for ANSI escape sequence parsing. Whitelist allowed sequences and discard or neutralize potentially malicious ones.
    • Content Security Policy (CSP): Implement a strong CSP to restrict script execution and resource loading, limiting XSS impact.
    • Regular Updates: Keep asciinema-player updated to benefit from security patches.

Attack Surface: Denial of Service (DoS) via Malformed JSON Recording Data

  • Description: A maliciously crafted asciinema recording file with malformed or excessively complex JSON data is provided. When asciinema-player attempts to parse this data, it leads to excessive resource consumption, potentially crashing the user's browser or significantly degrading performance, resulting in a Denial of Service.

  • asciinema-player Contribution to Attack Surface: asciinema-player's core functionality relies on parsing JSON data from the recording file. Vulnerabilities or inefficiencies in its JSON parsing logic directly contribute to this attack surface.

  • Example: A recording file contains deeply nested JSON objects or extremely large strings. Parsing this overly complex JSON by asciinema-player can consume excessive CPU and memory, freezing or crashing the user's browser tab.

  • Impact:

    • Player Unavailability: The player fails to load or function, preventing recording playback.
    • Browser Performance Degradation: User browser becomes slow and unresponsive.
    • Browser Crash: Browser tab or application crashes due to resource exhaustion.

  • Risk Severity: High

  • Mitigation Strategies:

    • Robust JSON Parsing and Error Handling: Implement secure and efficient JSON parsing with proper error handling to prevent crashes. Use a reliable JSON parsing library.
    • Input Validation and Limits on JSON Structure: Validate the structure and size of the JSON data. Set limits on nesting depth, string sizes, and overall file size to prevent processing of excessively complex recordings.
    • Resource Limits and Throttling in Parsing: Implement resource limits within the player's JSON parsing logic to prevent excessive CPU/memory usage. Throttling mechanisms can limit data processing rate.

Attack Surface: Denial of Service (DoS) via Resource Exhaustion through Excessive Terminal Output or ANSI Escape Sequences

  • Description: A recording with an extremely large volume of terminal output or a very high frequency of ANSI escape sequences is created. When asciinema-player renders this content, it can overwhelm the browser's rendering engine, leading to resource exhaustion and a Denial of Service.

  • asciinema-player Contribution to Attack Surface: asciinema-player is responsible for rendering terminal output and processing ANSI escape sequences. Inefficient rendering or processing of excessive output directly contributes to this DoS vector.

  • Example: A recording contains thousands of lines of text printed rapidly or an extremely high number of ANSI color changes in a short time. Rendering this by asciinema-player can consume excessive CPU/GPU, freezing or crashing the browser.

  • Impact:

    • Player Unresponsiveness: Player becomes unresponsive or very slow.
    • Browser Freeze or Crash: User browser freezes or crashes due to resource exhaustion.

  • Risk Severity: High

  • Mitigation Strategies:

    • Output Throttling and Buffering: Implement mechanisms to throttle rendering of terminal output, especially for rapid output. Buffer output and render in chunks.
    • Limit Rendering Rate: Limit the player's frame rate or update rate to prevent excessive rendering operations.
    • Resource Limits in Rendering Logic: Implement resource limits within the player's rendering logic to prevent excessive CPU/GPU usage.
    • Content Length Limits: Consider limits on recording length or maximum lines of output to be rendered to prevent processing of extremely large recordings.