analyzing-outlook-pst-for-email-forensics

import pypff
import os
import json
import hashlib
import email
import sys
from datetime import datetime
from collections import defaultdict
 
 
class PSTForensicAnalyzer:
    """Forensic analysis of Outlook PST/OST files."""
 
    def __init__(self, pst_path: str, output_dir: str):
        self.pst_path = pst_path
        self.output_dir = output_dir
        os.makedirs(output_dir, exist_ok=True)
        self.pst = pypff.file()
        self.pst.open(pst_path)
        self.messages = []
        self.attachments = []
        self.stats = defaultdict(int)
 
    def process_folder(self, folder, folder_path: str = ""):
        """Recursively process PST folders and extract messages."""
        folder_name = folder.name or "Root"
        current_path = f"{folder_path}/{folder_name}" if folder_path else folder_name
 
        for i in range(folder.number_of_sub_messages):
            try:
                message = folder.get_sub_message(i)
                msg_data = self.extract_message(message, current_path)
                if msg_data:
                    self.messages.append(msg_data)
                    self.stats["total_messages"] += 1
            except Exception as e:
                self.stats["parse_errors"] += 1
 
        for i in range(folder.number_of_sub_folders):
            try:
                subfolder = folder.get_sub_folder(i)
                self.process_folder(subfolder, current_path)
            except Exception:
                continue
 
    def extract_message(self, message, folder_path: str) -> dict:
        """Extract forensic metadata from a single email message."""
        msg_data = {
            "folder": folder_path,
            "subject": message.subject or "",
            "sender": message.sender_name or "",
            "sender_email": "",
            "creation_time": str(message.creation_time) if message.creation_time else None,
            "delivery_time": str(message.delivery_time) if message.delivery_time else None,
            "modification_time": str(message.modification_time) if message.modification_time else None,
            "has_attachments": message.number_of_attachments > 0,
            "attachment_count": message.number_of_attachments,
            "body_size": len(message.plain_text_body or b""),
            "html_size": len(message.html_body or b""),
        }
 
        # Extract transport headers for routing analysis
        headers = message.transport_headers
        if headers:
            msg_data["headers_present"] = True
            msg_data["headers_size"] = len(headers)
            # Parse key headers
            parsed = email.message_from_string(headers)
            msg_data["from_header"] = parsed.get("From", "")
            msg_data["to_header"] = parsed.get("To", "")
            msg_data["date_header"] = parsed.get("Date", "")
            msg_data["message_id"] = parsed.get("Message-ID", "")
            msg_data["x_originating_ip"] = parsed.get("X-Originating-IP", "")
            msg_data["received_headers"] = parsed.get_all("Received", [])
 
        # Process attachments
        for j in range(message.number_of_attachments):
            try:
                attachment = message.get_attachment(j)
                att_data = {
                    "message_subject": msg_data["subject"],
                    "name": attachment.name or f"attachment_{j}",
                    "size": attachment.size,
                    "content_type": "",
                }
                self.attachments.append(att_data)
                self.stats["total_attachments"] += 1
            except Exception:
                continue
 
        return msg_data
 
    def save_attachments(self, max_size_mb: int = 100):
        """Export attachments to disk for analysis."""
        att_dir = os.path.join(self.output_dir, "attachments")
        os.makedirs(att_dir, exist_ok=True)
 
        root = self.pst.get_root_folder()
        self._save_attachments_recursive(root, att_dir, max_size_mb)
 
    def _save_attachments_recursive(self, folder, att_dir, max_size_mb):
        for i in range(folder.number_of_sub_messages):
            try:
                message = folder.get_sub_message(i)
                for j in range(message.number_of_attachments):
                    att = message.get_attachment(j)
                    if att.size and att.size < max_size_mb * 1024 * 1024:
                        name = att.name or f"unknown_{i}_{j}"
                        safe_name = "".join(c if c.isalnum() or c in ".-_" else "_" for c in name)
                        path = os.path.join(att_dir, safe_name)
                        try:
                            data = att.read_buffer(att.size)
                            with open(path, "wb") as f:
                                f.write(data)
                        except Exception:
                            continue
            except Exception:
                continue
 
        for i in range(folder.number_of_sub_folders):
            try:
                self._save_attachments_recursive(folder.get_sub_folder(i), att_dir, max_size_mb)
            except Exception:
                continue
 
    def generate_report(self) -> str:
        """Generate comprehensive PST forensic analysis report."""
        root = self.pst.get_root_folder()
        self.process_folder(root)
 
        report = {
            "analysis_timestamp": datetime.now().isoformat(),
            "pst_file": self.pst_path,
            "pst_size_bytes": os.path.getsize(self.pst_path),
            "statistics": dict(self.stats),
            "messages": self.messages[:500],
            "attachments": self.attachments[:200],
        }
 
        report_path = os.path.join(self.output_dir, "pst_forensic_report.json")
        with open(report_path, "w") as f:
            json.dump(report, f, indent=2, default=str)
 
        print(f"[*] Total messages: {self.stats['total_messages']}")
        print(f"[*] Total attachments: {self.stats['total_attachments']}")
        print(f"[*] Parse errors: {self.stats['parse_errors']}")
        return report_path
 
    def close(self):
        self.pst.close()
 
 
def main():
    if len(sys.argv) < 3:
        print("Usage: python process.py <pst_file> <output_dir>")
        sys.exit(1)
    analyzer = PSTForensicAnalyzer(sys.argv[1], sys.argv[2])
    analyzer.generate_report()
    analyzer.close()
 
 
if __name__ == "__main__":
    main()

$ pffexport /evidence/jsmith_archive.pst -t /analysis/pst_output

pffexport 20231205 - libpff PST/OST Export Tool
=================================================
Input: /evidence/jsmith_archive.pst (2.3 GB)

Exporting PST contents...
  Folders:       45
  Messages:      12,456
  Attachments:   3,234
  Contacts:      567
  Calendar:      234
  Tasks:         89

Export completed in 3m 42s.

$ python3 pst_analyzer.py /analysis/pst_output /analysis/email_report

PST Forensic Analysis Report
==============================
Source: jsmith_archive.pst (john.smith@corporate.com)
Date Range: 2023-06-01 to 2024-01-18

--- Mailbox Statistics ---
  Total Emails:       12,456
  Sent:               4,567
  Received:           7,889
  With Attachments:   3,234
  Deleted (recovered): 234

--- Phishing / Suspicious Emails ---
Email #8923
  Date:        2024-01-15 14:30:22 UTC
  From:        "IT Support" <it-support@c0rporate-help.com>
  To:          john.smith@corporate.com
  Subject:     Urgent: Password Reset Required
  Headers:
    Return-Path:    bounce@mail-relay.c0rporate-help.com
    X-Originating-IP: 203.0.113.55
    Received:       from mail-relay.c0rporate-help.com (203.0.113.55)
    SPF:            FAIL (domain c0rporate-help.com)
    DKIM:           NONE
    DMARC:          FAIL
  Attachments:
    - Password_Reset_Form.xlsm (245 KB) SHA-256: 7a3b8c9d...e1f2a3b4
  Body Preview:  "Dear Employee, Your password will expire in 24 hours.
                  Please open the attached form to reset your credentials..."

--- Data Exfiltration Indicators ---
Email #9102
  Date:        2024-01-16 03:15:45 UTC
  From:        john.smith@corporate.com
  To:          j.smith.personal8842@protonmail.com
  Subject:     (no subject)
  Attachments:
    - archive_part1.7z (24.5 MB) - encrypted
    - archive_part2.7z (24.5 MB) - encrypted

Email #9103
  Date:        2024-01-16 03:18:22 UTC
  From:        john.smith@corporate.com
  To:          j.smith.personal8842@protonmail.com
  Subject:     Re:
  Attachments:
    - archive_part3.7z (18.2 MB) - encrypted

--- Keyword Hits ---
  "confidential":     45 emails
  "password":         23 emails
  "transfer":         12 emails
  "resign":           3 emails
  "delete evidence":  1 email (Email #9200, 2024-01-17 22:30:00 UTC)

Summary:
  Phishing emails detected:    1 (initial compromise vector)
  Suspicious sent emails:      5 (to personal accounts with attachments)
  Encrypted attachments:       3 (67.2 MB total - possible exfiltration)
  Report: /analysis/email_report/pst_forensic_report.json