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T1598.002 Spearphishing Attachment

Adversaries may send spearphishing messages with a malicious attachment to elicit sensitive information that can be used during targeting. Spearphishing for information is an attempt to trick targets into divulging information, frequently credentials or other actionable information. Spearphishing for information frequently involves social engineering techniques, such as posing as a source with a reason to collect information (ex: Establish Accounts or Compromise Accounts) and/or sending multiple, seemingly urgent messages.

All forms of spearphishing are electronically delivered social engineering targeted at a specific individual, company, or industry. In this scenario, adversaries attach a file to the spearphishing email. In some cases, they may rely upon the recipient populating information, then returning the file.25 The text of the spearphishing email usually tries to give a plausible reason why the file should be filled-in, such as a request for information from a business associate. In other cases, adversaries may leverage techniques such as HTML Smuggling to harvest user credentials via fake login portals.3

Adversaries may also use information from previous reconnaissance efforts (ex: Search Open Websites/Domains or Search Victim-Owned Websites) to craft persuasive and believable lures.

Item Value
ID T1598.002
Sub-techniques T1598.001, T1598.002, T1598.003, T1598.004
Tactics TA0043
Platforms PRE
Version 1.2
Created 02 October 2020
Last Modified 24 October 2025

Procedure Examples

ID Name Description
G0035 Dragonfly Dragonfly has used spearphishing with Microsoft Office attachments to enable harvesting of user credentials.6
G1008 SideCopy SideCopy has crafted generic lures for spam campaigns to collect emails and credentials for targeting efforts.14
G0121 Sidewinder Sidewinder has sent e-mails with malicious attachments that lead victims to credential harvesting websites.111213
G1033 Star Blizzard Star Blizzard has sent emails to establish rapport with targets eventually sending messages with attachments containing links to credential-stealing sites.87910

Mitigations

ID Mitigation Description
M1054 Software Configuration Use anti-spoofing and email authentication mechanisms to filter messages based on validity checks of the sender domain (using SPF) and integrity of messages (using DKIM). Enabling these mechanisms within an organization (through policies such as DMARC) may enable recipients (intra-org and cross domain) to perform similar message filtering and validation.41
M1017 User Training Users can be trained to identify social engineering techniques and spearphishing attempts.

References

  1. Australian Cyber Security Centre. (2012, December). Mitigating Spoofed Emails Using Sender Policy Framework. Retrieved November 17, 2024. ↩

  2. Ducklin, P. (2020, October 2). Serious Security: Phishing without links – when phishers bring along their own web pages. Retrieved October 20, 2020. ↩

  3. Matt Kiely. (2024, July 5). Smuggler’s Gambit: Uncovering HTML Smuggling Adversary in the Middle Tradecraft. Retrieved March 18, 2025. ↩

  4. Microsoft. (2020, October 13). Anti-spoofing protection in EOP. Retrieved October 19, 2020. ↩

  5. Ryan Hanson. (2016, September 24). phishery. Retrieved October 23, 2020. ↩

  6. US-CERT. (2018, March 16). Alert (TA18-074A): Russian Government Cyber Activity Targeting Energy and Other Critical Infrastructure Sectors. Retrieved June 6, 2018. ↩

  7. CISA, et al. (2023, December 7). Russian FSB Cyber Actor Star Blizzard Continues Worldwide Spear-phishing Campaigns. Retrieved June 13, 2024. ↩

  8. Microsoft Threat Intelligence. (2022, August 15). Disrupting SEABORGIUM’s ongoing phishing operations. Retrieved June 13, 2024. ↩

  9. Microsoft Threat Intelligence. (2023, December 7). Star Blizzard increases sophistication and evasion in ongoing attacks. Retrieved February 13, 2024. ↩

  10. Shields, W. (2024, January 18). Russian threat group COLDRIVER expands its targeting of Western officials to include the use of malware. Retrieved June 13, 2024. ↩

  11. Hegel, T. (2021, January 13). A Global Perspective of the SideWinder APT. Retrieved January 27, 2021. ↩

  12. Rewterz. (2020, April 20). Sidewinder APT Group Campaign Analysis. Retrieved January 29, 2021. ↩

  13. Cyble. (2020, September 26). SideWinder APT Targets with futuristic Tactics and Techniques. Retrieved January 29, 2021. ↩

  14. Threat Intelligence Team. (2021, December 2). SideCopy APT: Connecting lures victims, payloads to infrastructure. Retrieved June 13, 2022. ↩