CodeQL documentation
CodeQL resources

Uncontrolled command line

ID: rb/command-line-injection
Kind: path-problem
Security severity: 9.8
Severity: error
Precision: high
Tags:
   - correctness
   - security
   - external/cwe/cwe-078
   - external/cwe/cwe-088
Query suites:
   - ruby-code-scanning.qls
   - ruby-security-extended.qls
   - ruby-security-and-quality.qls

Click to see the query in the CodeQL repository

Code that passes user input directly to Kernel.system, Kernel.exec, or some other library routine that executes a command, allows the user to execute malicious code.

Recommendation

If possible, use hard-coded string literals to specify the command to run or library to load. Instead of passing the user input directly to the process or library function, examine the user input and then choose among hard-coded string literals.

If the applicable libraries or commands cannot be determined at compile time, then add code to verify that the user input string is safe before using it.

Example

The following example shows code that takes a shell script that can be changed maliciously by a user, and passes it straight to Kernel.system without examining it first.

class UsersController < ActionController::Base
  def create
    command = params[:command]
    system(command) # BAD
  end
end

References

  • © GitHub, Inc.
  • Terms
  • Privacy