Command execution without sanitization

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Metadata

ID: python-security/os-system

Language: Python

Severity: Error

Category: Security

CWE: 78

Description

Detect unsafe shell execution with the os module. We should ensure the command is safe before execution. Use shlex to sanitize user inputs.

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Non-Compliant Code Examples

os.system(f'mv {saved_file_path} {public_upload_file_path}')

command = f'convert "{temp_upload_file_path}" -resize 50% "{resized_image_path}"'
os.system(command)


command2 = f'convert "{temp_upload_file_path}" -resize 50% "{resized_image_path}"'
os.system(command4)

import os

directory = "/tmp"

# Use of unsanitized data to execute a process
os.system("/bin/ls")
os.system("/bin/ls " + directory)


os.system(f'mv {saved_file_path} {public_upload_file_path}')


def file_upload_api(request, app):
    file = request.files['file']

    if not _validate_file(file.filename):
        return {
            'message': 'Invalid file extension',
            'allowed_ext': ALLOWED_EXTENSIONS,
            'filename': file.filename
        }, 422

    saved_file_result = _save_temp_file(file, app)
    saved_file_path = saved_file_result['saved_path']

    file_name = Path(saved_file_path).name

    public_upload_file_path = os.path.join(app.config['PUBLIC_UPLOAD_FOLDER'], file_name)

    os.system(f'mv {saved_file_path} {public_upload_file_path}')

    return render_template('file_upload.html', file_url=f'{get_uploads_folder_url()}/{file_name}')

Compliant Code Examples

import os
import shlex

# Use of shlex() to sanitize data
os.system(shlex.escape("/bin/ls"))