MITRE ATT&CK Technique
Collection T1114.001
Description

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\<username>\Documents\Outlook Files` or `C:\Users\<username>\AppData\Local\Microsoft\Outlook`.(Citation: Microsoft Outlook Files)

Supported Platforms
Windows
Created

April 29, 2026

Last Updated

April 29, 2026

STIX Data
{'created': '2020-02-19T18:46:06.098Z',
 'created_by_ref': 'identity--c78cb6e5-0c4b-4611-8297-d1b8b55e40b5',
 'description': '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.\n'
                '\n'
                '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\\<username>\\Documents\\Outlook Files` or '
                '`C:\\Users\\<username>\\AppData\\Local\\Microsoft\\Outlook`.(Citation: '
                'Microsoft Outlook Files)',
 'external_references': [{'external_id': 'T1114.001',
                          'source_name': 'mitre-attack',
                          'url': 'https://attack.mitre.org/techniques/T1114/001'},
                         {'description': "N. O'Bryan. (2018, May 30). Managing "
                                         'Outlook Cached Mode and OST File '
                                         'Sizes. Retrieved February 19, 2020.',
                          'source_name': 'Outlook File Sizes',
                          'url': 'https://practical365.com/clients/office-365-proplus/outlook-cached-mode-ost-file-sizes/'},
                         {'description': 'Microsoft. (n.d.). Introduction to '
                                         'Outlook Data Files (.pst and .ost). '
                                         'Retrieved February 19, 2020.',
                          'source_name': 'Microsoft Outlook Files',
                          'url': 'https://support.office.com/en-us/article/introduction-to-outlook-data-files-pst-and-ost-222eaf92-a995-45d9-bde2-f331f60e2790'}],
 'id': 'attack-pattern--1e9eb839-294b-48cc-b0d3-c45555a2a004',
 'kill_chain_phases': [{'kill_chain_name': 'mitre-attack',
                        'phase_name': 'collection'}],
 'modified': '2025-10-24T17:48:29.669Z',
 'name': 'Local Email Collection',
 'object_marking_refs': ['marking-definition--fa42a846-8d90-4e51-bc29-71d5b4802168'],
 'spec_version': '2.1',
 'type': 'attack-pattern',
 'x_mitre_attack_spec_version': '3.2.0',
 'x_mitre_deprecated': False,
 'x_mitre_detection': '',
 'x_mitre_domains': ['enterprise-attack'],
 'x_mitre_is_subtechnique': True,
 'x_mitre_modified_by_ref': 'identity--c78cb6e5-0c4b-4611-8297-d1b8b55e40b5',
 'x_mitre_platforms': ['Windows'],
 'x_mitre_version': '1.1'}
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