MBOX Forensics to Extract & Investigate MBOX File Format

Emails continue to be the primary form of information exchange. Many times these emails are found in MBOX format. Such large volumes of files mean that these are often part of the digital investigation. Thus the need for MBOX forensics finds its way in. In this article, you will find all the information required to complete the forensic analysis of MBOX data. So first let us get a quick overview of MBOX and its subtypes.

Understand the MBOX Files and Their Role in Digital Forensics

MBOX is an offline email storage format where every email message is kept in a single file. It first found its use in UNIX machines however realizing its utility, many email clients and services started offering its support. Even when more modern and cloud-based email systems are available MBOX still maintains its usage but has shifted towards an archiving and backup role. As 

During forensic analysis of MBOX data, it’s important that investigators have all the information on its structure and function. Every new message in the MBOX begins from a “From” line. Apart from the email content detectives also get access to a wealth of information. Which includes sender and recipient details, timestamps, and metadata such as IP addresses and email headers. Moreover, MBOX is not just a single file rather it’s a family all of whom possess some unique characteristics of their own.

MBOX Variants

MBOXO

• Uses “From ” lines to determine message separator points
• Prepends a greater-than sign (“>”) to lines starting with “From “
• Can cause message corruption if not handled properly

MBOXRD

• Designed to solve MBOXO’s message corruption issues
• Employs “reversible From quoting”
• Prepends a greater-than sign (“>”) to lines starting with “From ” and removes it when reading

MBOXCL

• Uses a ‘Content-Length:’ header to determine message length
• Does not scan for “From ” lines
• Prepends a greater-than sign (“>”) to lines starting with “From “

MBOXCL2

• Similar to MBOXCL but does not use “From ” quoting
• Uses a “Content-Length:” header to determine message length

Next we start the tutorial on process of getting MBOX files for analysis.

Step By Step Guide to Extract MBOX for Further Forensics

Getting the MBOX may seem easy at first. However, if proper procedure is not maintained then it may not lead to accurate results. Whether you are using an automated tool or going for with the manual approach extraction steps remain the same. 

Step 1. Source Identification 

First of all, see where the MBOX files are kept. You can find them inside.

Email Clients: Many apps like Mozilla Thunderbird, Apple Mail, have native support for MBOX, though the exact variant may vary.

Backup Folder: MBOX data may also be present in raw format inside the regular folder of a machine. In system backups or archives.

Cloud Services: Cloud-based email service providers like Gmail give the option to pull data offline in MBOX format. This is useful in Google Takeout forensics also.

Step 2. Secure MBOX data

Extraction should only be attempted if the data is secure beyond any reasonable doubt. It is very important to disable any attempts to alter the evidence. Write blockers can help you with that. Moreover, instead of manually copy-pasting deploy forensic imaging tools to generate a bit-by-bit copy of all data that is in the MBOX file. 

Step 3. Perform Extraction

A typical auto extractor has three essential steps first locating the source, then selecting the MBOX format, and finally initiating the extraction process. Ensure that during the process no external disturbances occur and the files are safely deposited into the intended location. This location should be separate from the source.

Step 4. Verify Evidence Integrity

This is done to measure the authenticity of the source. The digital tagging of MBOX files usually happens by using checksums or hash values (e.g., SHA-256). This is the most non-intrusive way to ensure that the data has not been tampered with. This is done twice before and after extraction. Many forensic tools have built-in features to check the hash value and use them.

Step 5. Prepare for Analysis

Every successfully verified MBOX can be sent for digital forensics. Next, we are going to explain the best means to analyze the data inside MBOX evidence.

How to Analyze Email Data Present in MBOX Files Professionally

Use MailXaminer as it has tailor-made advanced search and analysis features for MBOX forensics. You can add attachments while scanning the MBOX files, and display malicious/suspicious IPs present in the email metadata. 

Use it to check for hash values during the analysis phase and maintain evidence consistency. Moreover, you can convert the extracted MBOX files to PDF. So, here is the list of steps you need to perform to analyze the MBOX data with this tool. 

• Step 1. Install and open the tool on the workstation.
• Step 2. Create a new case by filling in the Title, description, and Investigator in charge. 
• Step 3. Add new evidence > Select the MBOX option from the Email client menu.
• Step 4. Configure the required settings, IP identification, Hash value, etc, and press next.
• Step 5. Add source MBOX file by browsing it from the actual location.
• Step 6. Go to the search area and use the tool’s inbuilt filtering mechanism to get the insights
• Step 7. After analysis export the results and generate a report.

Secure and Present MBOX Forensics Data in Legal Proceedings

The MBOX forensics process does not end with analysis. The insights gained from this tool are the ones that would either prove or disprove an argument in a court of law.

Chain of Custody

Refers to the forensics practice of knowing at all times who all have the permission to handle the evidence.

Access Control

The evidence should only remain accessible to authorized personnel. Keep the MBOX forensics source file, the tool, and the results in a password-protected setup. 

Reporting and Documentation

Forensic analysts can understand the language of evidence, but it is not true for the vast majority of us. So it is their responsibility to present their findings in a manner that a layman can understand. The documentation should contain all processes done during extraction, analysis, and storage. Every step should have an explanation attached to justify it. The tool we discussed can perform reporting on every MBOX forensic activity done with it.

Legal Compliance

None of the efforts would be valid if they were not compliant with the local laws and regulations. A judge can outright dismiss the evidence if any discrepancy is found. That’s why all must be known and followed. Although, a privately held investigation for internal purposes is under less scrutiny even there a standard must be maintained.

Challenges and Best Practices in MBOX Forensics

No forensic-level analysis is free from challenges same is true for the process done on MBOX files. However, if investigators understand these obstacles beforehand they can ease up the process and minimize the effort required. For that, the best approach is to have a set of best practices that we provide after discussing the challenges that prompt their existence.

Large MBOX Files

As MBOX files store all email conversations in one place they can become exceedingly large. This increases the difficulties of all processes be it extraction, preservation, or analysis especially if done manually.

A solution would be to deploy a tool that can handle significantly large data sets without issues. Investigators can also segment the source MBOX files into manageable parts. However, do so with caution so as to not damage the evidence’s integrity. 

Data Corruption in MBOX

MBOX files are quite robust but this does not make them corruption proof. Improper handling, software issues, etc can cause sudden corruption. Moreover, some MBOX variants like “MBOXO” are more prone to corruption so check the type of MBOX and convert before analyzing.

Also keep two copies of the original document, a Master, and a working copy, and use genuine forensic tools that have a history of reliable performance.

Conclusion

In this guide on MBOX forensics, we made readers aware of the process and also gave guidelines on how to deal with challenges. Here we saw how MBOX being a single storage file has many different subtypes each of which behaves differently. Every aspect of the MBOX forensics lifecycle from identification to its presentation in a court is covered here. Moreover, you will find that there is no better way to analyze MBOX evidence from any source than to use email forensics software covered earlier.