Adversaries may target user email on local systems to collect sensitive information. Files containing email data can be acquired from a user’s local system, such as Outlook storage or cache files. Outlook stores data locally in offline data files with an extension of .ost. Outlook 2010 and later supports .ost file sizes up to 50GB, while earlier versions of Outlook support up to 20GB.(Citation: Outlook File Sizes) IMAP accounts in Outlook 2013 (and earlier) and POP accounts use Outlook Data Files (.pst) as opposed to .ost, whereas IMAP accounts in Outlook 2016 (and later) use .ost files. Both types of Outlook data files are typically stored in `C:\Users\\Documents\Outlook Files` or `C:\Users\\AppData\Local\Microsoft\Outlook`.(Citation: Microsoft Outlook Files)

Linked Issues

Issuelinks
is related to Techniques
is blocked by Out-of-Band Communications Channel
is blocked by Detect Local Email Collection via Outlook Data File Access and Command Line Tooling
is blocked by Encrypt Sensitive Information
is blocked by Continuous Monitoring
is blocked by Cybersecurity & Data Protection Attributes
is blocked by Use of External Technology Assets, Applications and/or Services (TAAS)
is blocked by Media & Data Retention
is blocked by Endpoint File Integrity Monitoring (FIM)
is blocked by Access Control For Mobile Devices
is blocked by Data Flow Enforcement – Access Control Lists (ACLs)
is blocked by Out-of-Band Channels
is blocked by Remote Access
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