During a security assessment, email adddress collection is a critical task. Manual extraction from API responses, such as those from a banking site's phonebook function, is inefficient when dealing with large volumes of JSON data.

Network inspection (via browser developer tools) reveals the target endpoint returns email information in a structured JSON format. While regex is a possible solution, parsing the JSON directly is more reliable and efficient.

Preparation Save the complete JSON response from the relevant API call to a local file named email.json. Viewing this file in a browser or editor helps identify the data structure. The target email addresses are nested within a array under the key "selectors", each stored in a "selectorvalue" field.

Core Parsing Logic The essential code to extract these values is straightforward.

import json

with open('email.json', 'r', encoding='utf-8') as json_file:
    json_data = json.load(json_file)

for entry in json_data["selectors"]:
    email_address = entry["selectorvalue"]
    print(email_address)

Enhanced Script with File Managemnet To create a reusable utility, the script is enhanced with command-line arguments and robust file handling.

import json
import os
import sys

INTERMEDIATE_FILE = "temp_output.txt"

def extract_emails(json_filename):
    """Reads JSON file and extracts email addresses from the selectors array."""
    try:
        with open(json_filename, 'r', encoding='utf-8') as f:
            dataset = json.load(f)
    except FileNotFoundError:
        print(f"Error: File '{json_filename}' not found.")
        sys.exit(1)
    except json.JSONDecodeError:
        print(f"Error: File '{json_filename}' contains invalid JSON.")
        sys.exit(1)

    email_list = []
    for item in dataset.get("selectors", []):
        email = item.get("selectorvalue")
        if email:
            email_list.append(email)
    return email_list

def write_results(data_list, output_filename):
    """Writes a list of strings to a file, each on a new line."""
    with open(output_filename, 'w', encoding='utf-8') as f:
        for line in data_list:
            f.write(line + '\n')

if __name__ == '__main__':
    # Validate command-line argument for host identifier
    if len(sys.argv) != 2:
        print('Usage: python email_parser.py <host_identifier>')
        sys.exit(1)

    host_tag = sys.argv[1]
    final_filename = f"{host_tag}-email.txt"

    print(f"Target output file: {final_filename}")

    # Clear intermediate file if it exists from a previous run
    if os.path.exists(INTERMEDIATE_FILE):
        open(INTERMEDIATE_FILE, 'w').close()

    # Core process: Extract and write emails
    emails = extract_emails('email.json')
    write_results(emails, INTERMEDIATE_FILE)

    # Manage final file: replace if exists, otherwise rename.
    if os.path.exists(final_filename):
        os.remove(final_filename)
    os.rename(INTERMEDIATE_FILE, final_filename)

    print(f"Extraction complete. Results saved to '{final_filename}'.")

Execution Examples

# Incorrect usage prompts help message
python email_parser.py

# First run creates 'ccb-email.txt'
python email_parser.py ccb

# Subsequent run overwrites the existing 'ccb-email.txt'
python email_parser.py ccb