T1566.001: Spearphishing Attachment
Adversaries may send spearphishing emails with a malicious attachment in an attempt to gain access to victim systems. Spearphishing attachment is a specific variant of spearphishing. Spearphishing attachment is different from other forms of spearphishing in that it employs the use of malware attached to an email. 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 and usually rely upon User Execution to gain execution.[1] Spearphishing may also involve social engineering techniques, such as posing as a trusted source.
There are many options for the attachment such as Microsoft Office documents, executables, PDFs, or archived files. Upon opening the attachment (and potentially clicking past protections), the adversary's payload exploits a vulnerability or directly executes on the user's system. The text of the spearphishing email usually tries to give a plausible reason why the file should be opened, and may explain how to bypass system protections in order to do so. The email may also contain instructions on how to decrypt an attachment, such as a zip file password, in order to evade email boundary defenses. Adversaries frequently manipulate file extensions and icons in order to make attached executables appear to be document files, or files exploiting one application appear to be a file for a different one.
Security context for executives and security teams
T1566.001: Spearphishing Attachment describes Adversaries may send spearphishing emails with a malicious attachment in an attempt to gain access to victim systems. Spearphishing attachment is a specific variant of spearphishing. Spearphishing attachment is different from other forms of spearphishing in that it employs the use of malware attached to an email. 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 an...
Executive priority
T1566.001: Spearphishing Attachment is an official MITRE ATT&CK technique. Glexia treats it as defensive behavior context for prioritizing monitoring, control validation, and response planning without using the object by itself as an attribution claim.
Technical view
Security teams should validate T1566.001: Spearphishing Attachment by reviewing the official ATT&CK relationships, mapped tactics (initial-access), supported platforms (Linux, macOS, Windows), and available local telemetry before making detection or mitigation decisions.
Likely telemetry
- Official ATT&CK relationships and object metadata
- Network, endpoint, and security-tool telemetry
Detection direction
- Validate whether T1566.001: Spearphishing Attachment appears in your detection coverage and tabletop scenarios.
- Use the object to align executive risk language with SOC, incident response, and detection engineering work.
- Do not treat ATT&CK relationship context as attribution without corroborating evidence.
Mitigation priorities
- Map the object to existing controls and identify missing telemetry or response ownership.
- Prioritize mitigations that reduce exposure on the listed platforms and tactics.
- Review adjacent ATT&CK relationships before changing policy, detections, or reporting language.
Additional notes and limits
Baseline Glexia take generated from the official MITRE ATT&CK STIX object, source hash, tactics, platforms, and detection fields. It is safe to replace with a richer model-generated take for the same source hash later.
This baseline take is source-grounded and schema-validated, but it does not include environment-specific telemetry, incident evidence, or threat-intelligence corroboration.
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Spearphishing Attachment
Adversaries may send spearphishing emails with a malicious attachment in an attempt to gain access to victim systems. Spearphishing attachment is a specific variant of spearphishing. Spearphishing attachment is different from other forms of spearphishing in that it employs the use of malware attached to an email. 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 and usually rely upon User Execution to gain execution.[1] Spearphishing may also involve social engineering techniques, such as posing as a trusted source.
There are many options for the attachment such as Microsoft Office documents, executables, PDFs, or archived files. Upon opening the attachment (and potentially clicking past protections), the adversary's payload exploits a vulnerability or directly executes on the user's system. The text of the spearphishing email usually tries to give a plausible reason why the file should be opened, and may explain how to bypass system protections in order to do so. The email may also contain instructions on how to decrypt an attachment, such as a zip file password, in order to evade email boundary defenses. Adversaries frequently manipulate file extensions and icons in order to make attached executables appear to be document files, or files exploiting one application appear to be a file for a different one.
How security teams should use this page
Treat this object as behavior context, not an attribution claim. Validate the related groups, software, data sources, and mitigations against official ATT&CK relationships and your own telemetry before making control-coverage decisions.
Related techniques
This mirrors the MITRE pattern of making group, software, campaign, and technique relationships scannable. Relationship notes come from mirrored ATT&CK relationship text when available.
| Domain | ID | Name | Relationship / procedure |
|---|---|---|---|
| Enterprise | T1566 | Phishing | This object subtechnique of Phishing. |
| Enterprise | T1193 | Spearphishing Attachment | Spearphishing Attachment revoked by this object. |
Groups, software, and campaigns
G0080: Cobalt Group
Cobalt Group is a financially motivated threat group that has primarily targeted financial institutions since at least 2016. The group has conducted intrusions to steal money via targeting ATM systems, card processing, payment systems and SWIFT systems. Cobalt Group has mainly targeted banks in Eastern Europe, Central Asia, and Southeast Asia. One of the alleged leaders was arrested in Spain in early 2018, but the group still appears to be active. The group has been known to target organizations in order to use their access to then compromise additional victims.[1][2][3][4][5][6][7] Reporting indicates there may be links between Cobalt Group and both the malware Carbanak and the group Carbanak.[8]
G0032: Lazarus Group
Lazarus Group is a North Korean state-sponsored cyber threat group attributed to the Reconnaissance General Bureau (RGB). [1] [2] Lazarus Group has been active since at least 2009 and is reportedly responsible for the November 2014 destructive wiper attack on Sony Pictures Entertainment, identified by Novetta as part of Operation Blockbuster. Malware used by Lazarus Group correlates to other reported campaigns, including Operation Flame, Operation 1Mission, Operation Troy, DarkSeoul, and Ten Days of Rain.[3]
North Korea’s cyber operations have shown a consistent pattern of adaptation, forming and reorganizing units as national priorities shift. These units frequently share personnel, infrastructure, malware, and tradecraft, making it difficult to attribute specific operations with high confidence. Public reporting often uses “Lazarus Group” as an umbrella term for multiple North Korean cyber operators conducting espionage, destructive attacks, and financially motivated campaigns.[4][5][6]
G1031: Saint Bear
Saint Bear is a Russian-nexus threat actor active since early 2021, primarily targeting entities in Ukraine and Georgia. The group is notable for a specific remote access tool, Saint Bot, and information stealer, OutSteel in campaigns. Saint Bear typically relies on phishing or web staging of malicious documents and related file types for initial access, spoofing government or related entities.[1][2] Saint Bear has previously been confused with Ember Bear operations, but analysis of behaviors, tools, and targeting indicates these are distinct clusters.
G0081: Tropic Trooper
Tropic Trooper is an unaffiliated threat group that has led targeted campaigns against targets in Taiwan, the Philippines, and Hong Kong. Tropic Trooper focuses on targeting government, healthcare, transportation, and high-tech industries and has been active since 2011.[1][2][3]
G0037: FIN6
G0007: APT28
APT28 is a threat group that has been attributed to Russia's General Staff Main Intelligence Directorate (GRU) 85th Main Special Service Center (GTsSS) military unit 26165.[1][2] This group has been active since at least 2004.[3][4][5][6][7][8][9][10][11][12][13]
APT28 reportedly compromised the Hillary Clinton campaign, the Democratic National Committee, and the Democratic Congressional Campaign Committee in 2016 in an attempt to interfere with the U.S. presidential election.[5] In 2018, the US indicted five GRU Unit 26165 officers associated with APT28 for cyber operations (including close-access operations) conducted between 2014 and 2018 against the World Anti-Doping Agency (WADA), the US Anti-Doping Agency, a US nuclear facility, the Organization for the Prohibition of Chemical Weapons (OPCW), the Spiez Swiss Chemicals Laboratory, and other organizations.[14] Some of these were conducted with the assistance of GRU Unit 74455, which is also referred to as Sandworm Team.
G0018: admin@338
admin@338 is a China-based cyber threat group. It has previously used newsworthy events as lures to deliver malware and has primarily targeted organizations involved in financial, economic, and trade policy, typically using publicly available RATs such as PoisonIvy, as well as some non-public backdoors. [1]
G0112: Windshift
G0060: BRONZE BUTLER
BRONZE BUTLER is a cyber espionage group with likely Chinese origins that has been active since at least 2008. The group primarily targets Japanese organizations, particularly those in government, biotechnology, electronics manufacturing, and industrial chemistry.[1][2][3]
G0090: WIRTE
WIRTE is a cyberespionage actor, believed to be a subgroup of the Hamas-affiliated Gaza Cybergang, that has been active since at least August 2018. WIRTE has targeted diplomatic, financial, military, legal, and technology organizations across the Middle East, North Africa, and in Europe to gather intelligence. WIRTE has remained persistently active despite the ongoing Israel-Hamas conflict and has expanded their operations to include wiper malware attacks against Israeli targets.[1][2][3][4]
G0069: MuddyWater
MuddyWater is a cyber espionage group assessed to be a subordinate element within Iran's Ministry of Intelligence and Security (MOIS).[1] Since at least 2017, MuddyWater has targeted a range of government and private organizations across sectors, including telecommunications, local government, finance, defense, and oil and natural gas organizations, in the Middle East (specifically the UAE and Saudi Arabia), Asia, Africa, Europe, and North America. MuddyWater has reused domains dating back to October 2025, and has a preference for NameCheap and Hosterdaddy Private Limited (AS136557). In late 2025 and early 2026, MuddyWater used commercial satellite internet (i.e., Starlink) for command and control (C2) communication. [2][3][4][5][6][7][8][9][10][11][12][13]
G0045: menuPass
menuPass is a threat group that has been active since at least 2006. Individual members of menuPass are known to have acted in association with the Chinese Ministry of State Security's (MSS) Tianjin State Security Bureau and worked for the Huaying Haitai Science and Technology Development Company.[1][2]
menuPass has targeted healthcare, defense, aerospace, finance, maritime, biotechnology, energy, and government sectors globally, with an emphasis on Japanese organizations. In 2016 and 2017, the group is known to have targeted managed IT service providers (MSPs), manufacturing and mining companies, and a university.[3][4][5][6][7][1][2]
S0669: KOCTOPUS
S0447: Lokibot
Lokibot is a widely distributed information stealer that was first reported in 2015. It is designed to steal sensitive information such as usernames, passwords, cryptocurrency wallets, and other credentials. Lokibot can also create a backdoor into infected systems to allow an attacker to install additional payloads.[1][2][3]
S0331: Agent Tesla
Agent Tesla is a spyware Trojan written for the .NET framework that has been observed since at least 2014.[1][2][3]
S1064: SVCReady
S1066: DarkTortilla
DarkTortilla is a highly configurable .NET-based crypter that has been possibly active since at least August 2015. DarkTortilla has been used to deliver popular information stealers, RATs, and payloads such as Agent Tesla, AsyncRat, NanoCore, RedLine, Cobalt Strike, and Metasploit.[1]
S0428: PoetRAT
PoetRAT is a remote access trojan (RAT) that was first identified in April 2020. PoetRAT has been used in multiple campaigns against the private and public sectors in Azerbaijan, including ICS and SCADA systems in the energy sector. The STIBNITE activity group has been observed using the malware. PoetRAT derived its name from references in the code to poet William Shakespeare. [1][2][3]
S0148: RTM
S0622: AppleSeed
S0458: Ramsay
S9037: RustyWater
RustyWater is a Rust-based implant used by MuddyWater. Historically, MuddyWater has used PowerShell-based tools and RustyWater reflects a shift in tooling, demonstrating better techniques for defense evasion and reverse engineering.[1]
S0011: Taidoor
S0585: Kerrdown
C0028: 2015 Ukraine Electric Power Attack
2015 Ukraine Electric Power Attack was a Sandworm Team campaign during which they used BlackEnergy (specifically BlackEnergy3) and KillDisk to target and disrupt transmission and distribution substations within the Ukrainian power grid. This campaign was the first major public attack conducted against the Ukrainian power grid by Sandworm Team.
C0001: Frankenstein
Frankenstein was described by security researchers as a highly-targeted campaign conducted by moderately sophisticated and highly resourceful threat actors in early 2019. The unidentified actors primarily relied on open source tools, including Empire. The campaign name refers to the actors' ability to piece together several unrelated open-source tool components.[1]
C0015: C0015
C0015 was a ransomware intrusion during which the unidentified attackers used Bazar, Cobalt Strike, and Conti, along with other tools, over a 5 day period. Security researchers assessed the actors likely used the widely-circulated Conti ransomware playbook based on the observed pattern of activity and operator errors.[1]
C0016: Operation Dust Storm
Operation Dust Storm was a long-standing persistent cyber espionage campaign that targeted multiple industries in Japan, South Korea, the United States, Europe, and several Southeast Asian countries. By 2015, the Operation Dust Storm threat actors shifted from government and defense-related intelligence targets to Japanese companies or Japanese subdivisions of larger foreign organizations supporting Japan's critical infrastructure, including electricity generation, oil and natural gas, finance, transportation, and construction.[1]
Operation Dust Storm threat actors also began to use Android backdoors in their operations by 2015, with all identified victims at the time residing in Japan or South Korea.[1]
C0037: Water Curupira Pikabot Distribution
Pikabot was distributed in Water Curupira Pikabot Distribution throughout 2023 by an entity linked to BlackBasta ransomware deployment via email attachments. This activity followed the take-down of QakBot, with several technical overlaps and similarities with QakBot, indicating a possible connection. The identified activity led to the deployment of tools such as Cobalt Strike, while coinciding with campaigns delivering DarkGate and IcedID en route to ransomware deployment.[1]
All related ATT&CK context
Mitigation direction
Object version and sync metadata
The fields below describe the current mirrored snapshot. When Glexia retains multiple ATT&CK source imports, you can open the table to compare the same object across releases (hashes and MITRE timestamps). For MITRE’s own release notes and roadmap, see ATT&CK resources — Updates.
Imported snapshots across ATT&CK releases(3)
| Release | Bundle imported | Object version | Modified | Status | Raw hash |
|---|---|---|---|---|---|
| 20.0 | 2.2 | Current bundle | cf2053e3f1b1… | ||
| 19.2 | 2.2 | Older bundle | 2330d6693b0d… | ||
| 19.1 | 2.2 | Older bundle | 2330d6693b0d… |
Mirrored ATT&CK source object
The raw object is retained through the mirrored ATT&CK source bundle and object hash. The raw endpoint returns the exact object from the mirrored bundle when available.
External references and citations
MITRE external references are preserved separately from Glexia analysis so citations remain traceable to their original source records.
- [1]Unit 42 DarkHydrus July 2018
Falcone, R., et al. (2018, July 27). New Threat Actor Group DarkHydrus Targets Middle East Government. Retrieved August 2, 2018.
Open source URL - [2]ACSC Email Spoofing
Australian Cyber Security Centre. (2012, December). Mitigating Spoofed Emails Using Sender Policy Framework. Retrieved November 17, 2024.
Open source URL - [3]Elastic - Koadiac Detection with EQL
Stepanic, D.. (2020, January 13). Embracing offensive tooling: Building detections against Koadic using EQL. Retrieved November 17, 2024.
Open source URL - [4]Microsoft Anti Spoofing
Microsoft. (2020, October 13). Anti-spoofing protection in EOP. Retrieved October 19, 2020.
Open source URL - [5]mitre-attackT1566.001Open source URL
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