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Email Collection: Local Email Collection
Other sub-techniques of Email Collection (3)
ID | Name |
---|---|
T1114.001 | Local Email Collection |
T1114.002 | Remote Email Collection |
T1114.003 | Email Forwarding Rule |
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.[1] 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
.[2]
Procedure Examples
Name | Description |
---|---|
APT1 |
APT1 uses two utilities, GETMAIL and MAPIGET, to steal email. GETMAIL extracts emails from archived Outlook .pst files.[3] |
Carbanak |
Carbanak searches recursively for Outlook personal storage tables (PST) files within user directories and sends them back to the C2 server.[4] |
CosmicDuke |
CosmicDuke searches for Microsoft Outlook data files with extensions .pst and .ost for collection and exfiltration.[5] |
Crimson |
Crimson contains a command to collect and exfiltrate emails from Outlook.[6] |
Emotet |
Emotet has been observed leveraging a module that scrapes email data from Outlook.[7] |
Empire |
Empire has the ability to collect emails on a target system.[8] |
Magic Hound |
Magic Hound has collected .PST archives.[9] |
Pupy |
Pupy can interact with a victim’s Outlook session and look through folders and emails.[10] |
Smoke Loader |
Smoke Loader searches through Outlook files and directories (e.g., inbox, sent, templates, drafts, archives, etc.).[11] |
Mitigations
Mitigation | Description |
---|---|
Encrypt Sensitive Information |
Use of encryption provides an added layer of security to sensitive information sent over email. Encryption using public key cryptography requires the adversary to obtain the private certificate along with an encryption key to decrypt messages. |
Detection
Monitor processes and command-line arguments for actions that could be taken to gather local email files. Monitor for unusual processes accessing local email files. Remote access tools with built-in features may interact directly with the Windows API to gather information. Information may also be acquired through Windows system management tools such as Windows Management Instrumentation and PowerShell.
References
- N. O'Bryan. (2018, May 30). Managing Outlook Cached Mode and OST File Sizes. Retrieved February 19, 2020.
- Microsoft. (n.d.). Introduction to Outlook Data Files (.pst and .ost). Retrieved February 19, 2020.
- Mandiant. (n.d.). APT1 Exposing One of China’s Cyber Espionage Units. Retrieved July 18, 2016.
- Bennett, J., Vengerik, B. (2017, June 12). Behind the CARBANAK Backdoor. Retrieved June 11, 2018.
- F-Secure Labs. (2014, July). COSMICDUKE Cosmu with a twist of MiniDuke. Retrieved July 3, 2014.
- Huss, D.. (2016, March 1). Operation Transparent Tribe. Retrieved June 8, 2016.
- CIS. (2018, December 12). MS-ISAC Security Primer- Emotet. Retrieved March 25, 2019.
- Schroeder, W., Warner, J., Nelson, M. (n.d.). Github PowerShellEmpire. Retrieved April 28, 2016.
- Mandiant. (2018). Mandiant M-Trends 2018. Retrieved July 9, 2018.
- Nicolas Verdier. (n.d.). Retrieved January 29, 2018.
- Baker, B., Unterbrink H. (2018, July 03). Smoking Guns - Smoke Loader learned new tricks. Retrieved July 5, 2018.