Recovering Evidence From Deleted Microsoft 365 User Accounts

DELETEDM365ACCOUNTS · A GUIDE FOR UK LAWYERS Recovering Evidence from Deleted Microsoft 365 User Accounts Soft Deletion, Inactive Mailboxes, Retention and the Leaver Who Left Before the Hold COMPUTER FORENSICS LAB

§ ABOUT THE AUTHOR PREPARED BY COMPUTER FORENSICS LAB E-DISCOVERY TEAM ESTABLISHED 2007 · LONDON ISO 17025-ALIGNED PROCEDURES DELETED-ACCOUNT RECOVERY

§ CONTENTS In this guide 01 Executive summary 02 The problem in plain English: the leaver process is a deletion engine 03 The lifecycle of a deleted account: soft deletion, inactive state, hard deletion 04 What survives where: mailbox, One Drive, Teams, audit logs and licences 05 Preservation and collection before and after the clocks run 06 When the account is gone: reconstruction from the rest of the estate 07 Leaver processes and preservation duties: the legal consequences 08 Source architecture: where else the evidence lives 09 Worked examples 10 Common mistakes and technical limitations 11 Questions to ask · Suggested wording 12 Checklist and red flags · When to involve a digital forensic expert 13 Frequently asked questions 14 Glossary · References · Disclaimer · How a specialist laboratory can assist

§ 01 · ORIENTATION Executive summary THE HEADLINE POINT: ADELETEDMICROSOFT365ACCOUNTPASSESTHROUGH RECOVERABLESTATESWITHCLOCKSATTACHED: KNOWTHESTATE, ACTINSIDETHE CLOCK, ANDWHENTHECLOCKHASRUN, RECONSTRUCTFROMTHEESTATETHEUSER COULD NOT TAKE WITH THEM

§ 02 · FIRST PRINCIPLES The problem in plain English: the leaver process is a deletion engine

§ 03 · THELIFECYCLE The lifecycle of a deleted account: soft deletion, inactive state, hard deletion

§ 04 · WHATSURVIVESWHERE What survives where: mailbox, One Drive, Teams, audit logs and licences

§ 05 · BEATINGTHECLOCKS Preservation and collection before and after the clocks run

§ 06 · AFTERTHECLOCKS When the account is gone: reconstruction from the rest of the estate

§ 07 · THELEGALFRAME Leaver processes and preservation duties: the legal consequences

§ 08 · THEWIDERMAP Source architecture: where else the evidence lives EVIDENCE MAILBOX RETENTION DIRECTORY SOFT- DELETED / COUNTERPARTS + BACKUPS RESTORED SHARED STORES + DEVICES USER INACTIVE ONEDRIVE AUDIT / (HOLD) STAGE LAYER

§ 09 · IN THE WILD Worked examples EXAMPLE1 · THERESTOREONDAYTWENTY - SIX EXAMPLE2 · THECUSTODIANREBUILTFROMEVERYONEELSE EXAMPLE3 · THELEAVERPROCESSTHATRANAFTERTHELETTER

§ 10 · WHEREITGOESWRONG Common mistakes and technical limitations Common mistakes Technical limitations

§ 11 · INTERROGATORIES & DRAFTING AIDS Questions to ask · Suggested wording Ask your client Ask your opponent Ask your e Discovery / forensic provider ANDPOLICIES

§ 12 · QUICK CONTROL Checklist and red flags · When to involve a digital forensic expert The deleted-account checklist Red flags When to involve a digital forensic expert

§ 13 · COMMON QUESTIONS Frequently asked questions IT deleted the account last week. Is the data gone? What is an inactive mailbox and how do we get one? The account was hard-deleted a year ago with no hold. What now? Our leaver process deleted a relevant account after the dispute began. How bad is it? Doesn't UK GDPR require us to delete leavers' data? Can we tell whether the opponent's deleted custodian is really unrecoverable?

§ 14 · REFERENCE Glossary Sources and authoritative references 31 · CPR Part 35: justice.gov.uk, Part DISCLAIMER

§ HOW A SPECIALIST LABORATORY CAN ASSIST Working with Computer Forensics Lab Speak to a forensic examiner, not a salesperson. INSTRUCTTHELAB NEWENQUIRIESEMAILE - DISCOVERY