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Attack Tree Analysis for urfave/cli

Objective: To execute arbitrary code on the system running the urfave/cli application, or to cause a denial-of-service (DoS) condition specific to the CLI application's functionality.

Attack Tree Visualization

+-------------------------------------------------+ | Execute Arbitrary Code OR Cause CLI-Specific DoS | +-------------------------------------------------+ | +-------------------------+ | Exploit Input Handling | [HIGH RISK] +-------------------------+ | +---------+ | String | | Parsing | +---------+ | +---+---+---+---+ | U | O | F | S | +-+-+-+-+ | | | | | +---------------------+ | | | | +----------------[CRITICAL]-----+ | | +--------[HIGH RISK]---------------+ | +---------+---------+ | | | |U [CRITICAL]| O | F [CRITICAL]| S [CRITICAL]| +---------+---------+

Attack Tree Path: Exploit Input Handling (High-Risk Path)

  • Overall Description: This is the primary attack vector, focusing on how user-supplied data (through command-line arguments, flags, or environment variables) can be manipulated to compromise the application. The core issue is insufficient or absent input validation and sanitization.

  • Why High Risk: Input validation flaws are extremely common and often lead to severe vulnerabilities. Attackers actively seek out applications with weak input handling.

  • String Parsing: This sub-category deals with vulnerabilities arising from how the application processes string inputs.

    • U - Unvalidated/Unsanitized Input (Critical Node):

      • Description: The application accepts string input without checking its length, content, or format. This is the fundamental flaw that enables many other attacks.
      • Attack Examples:
        • Injecting SQL code into a database query.
        • Injecting JavaScript code into a web page (Cross-Site Scripting - XSS, if the CLI output is used in a web context).
        • Injecting shell commands (if the input is used in a system call).
        • Providing excessively long strings to cause a denial-of-service.
      • Mitigation:
        • Always validate and sanitize string inputs.
        • Use regular expressions to enforce allowed character sets and lengths (whitelisting).
        • Use a dedicated input validation library.
        • Never directly use user-provided strings in system calls, database queries, or file paths without thorough sanitization.

    • O - Overflow:

      • Description: While Go is generally memory-safe, extremely long strings could potentially cause memory exhaustion (DoS). In rare cases with unsafe code, buffer overflows are possible.
      • Attack Examples:
        • Providing a multi-gigabyte string as input to exhaust memory.
      • Mitigation:
        • Implement reasonable length limits on string inputs.
        • Monitor memory usage.

    • F - Format String Vulnerability (Critical Node):

      • Description: The application uses user-provided input as the format string in a function like fmt.Printf. This allows an attacker to control the formatting process and potentially read or write to arbitrary memory locations.
      • Attack Examples:
        • Using format specifiers like %x to leak memory contents.
        • Using format specifiers like %n to write to memory (though more difficult in Go than C/C++).
      • Mitigation:
        • Never use user-provided input as the format string in fmt.Printf or similar functions. Use separate arguments for the format string and the values.

    • S - Special Character Injection (Critical Node):

      • Description: The application uses user-provided strings in contexts where special characters have meaning (e.g., shell commands, SQL queries, HTML). This allows an attacker to inject commands or manipulate the intended logic.
      • Attack Examples:
        • Injecting a semicolon (;) followed by a malicious command into a string that's used in a shell command.
        • Injecting single quotes (') and SQL code into a database query.
        • Injecting <script> tags into HTML output.
      • Mitigation:
        • Avoid using user-provided strings directly in shell commands.
        • If absolutely necessary, use a well-vetted escaping/quoting library specifically designed for the target shell.
        • Prefer using structured APIs (e.g., Go's os/exec package with separate arguments) over constructing shell commands as strings.
        • Use parameterized queries for databases.
        • Use appropriate encoding/escaping functions for HTML output.

Attack Tree Path: Environment Variable Manipulation (Implicitly High Risk within Input Handling)

  • Overall Description: Although not explicitly shown as a separate branch in this sub-tree, environment variables are a form of input and are therefore subject to the same vulnerabilities as command-line arguments. If the application reads configuration from environment variables without proper validation, an attacker who can control the environment can inject malicious values.
    • Why High Risk: Attackers with even limited access to a system might be able to modify environment variables. If the application blindly trusts these variables, it can be easily compromised.
    • Mitigation:
      • Validate environment variables in the same way as command-line flags.
      • Document which environment variables are used and their expected formats.
      • Use a secure method for setting environment variables in production (e.g., container orchestration system secrets).