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Attack Surface Analysis for spf13/cobra

Attack Surface: Command Injection

Attack Surface: Command Injection

  • Description: Attackers inject malicious code through command arguments or flags, leading to unauthorized command execution on the host system.
  • Cobra's Contribution: Cobra's core function is to parse command-line arguments and flags, providing the mechanism through which user-supplied data enters the application. While Cobra itself doesn't execute the injected code, it's the gateway for the malicious input. The vulnerability lies in how the application subsequently uses this data.
  • Example:
    • Command: mycli backup --source /home/user/data --destination "; rm -rf /; #"
    • Cobra parses --destination and provides its value to the application. If the application uses this value directly in a shell command without sanitization, the injected command executes.
  • Impact: Complete system compromise, data loss, data exfiltration, malware installation.
  • Risk Severity: Critical
  • Mitigation Strategies:
    • Developer:
      • Strict Input Validation: Use allow-lists (whitelists) to define exactly what is permitted for each argument and flag. Reject anything that doesn't match.
      • Input Sanitization: Escape or remove dangerous characters before using the input in any system-level operation.
      • Avoid Shell Commands: Prefer using Go's os/exec with explicit arguments (e.g., exec.Command("cp", source, dest)).
      • Parameterization: Use parameterized queries or equivalents when interacting with other services.
    • User:
      • Be extremely cautious about command arguments, especially from untrusted sources.
      • Avoid piping untrusted output into Cobra-based applications.

Attack Surface: Subcommand Hijacking

Attack Surface: Subcommand Hijacking

  • Description: Attackers trigger unintended or hidden subcommands, potentially bypassing security controls or accessing privileged functionality.
  • Cobra's Contribution: Cobra's hierarchical subcommand structure is the direct enabler of this attack surface. If the application relies on user input to determine which subcommand to execute, and that input is not strictly validated against a known-good list of subcommands, hijacking is possible.
  • Example:
    • Hidden subcommand: mycli internal debug --reset-all.
    • If an attacker can manipulate input (e.g., a config file, a crafted URL) to make the application's Cobra-based command parsing logic select this hidden subcommand, they gain unauthorized access.
  • Impact: Execution of unauthorized actions, privilege escalation, data modification, denial of service.
  • Risk Severity: High
  • Mitigation Strategies:
    • Developer:
      • Static Command Structure: Define the command hierarchy statically. Avoid dynamic subcommand generation based on user input.
      • Explicit Command Mapping: If dynamic execution is unavoidable, use a strict, pre-defined mapping between input and allowed subcommands. Do not use user input directly as a subcommand name.
      • Input Validation: Validate even subcommand names.
    • User:
      • Be aware of documented commands. Investigate unexpected behavior.