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MITRE ATT&CK® Technique

T1566.003: Spearphishing via Service

Adversaries may send spearphishing messages via third-party services in an attempt to gain access to victim systems. Spearphishing via service is a specific variant of spearphishing. It is different from other forms of spearphishing in that it employs the use of third party services rather than directly via enterprise email channels.

All forms of spearphishing are electronically delivered social engineering targeted at a specific individual, company, or industry. In this scenario, adversaries send messages through various social media services, personal webmail, and other non-enterprise controlled services.[1] These services are more likely to have a less-strict security policy than an enterprise. As with most kinds of spearphishing, the goal is to generate rapport with the target or get the target's interest in some way. Adversaries will create fake social media accounts and message employees for potential job opportunities. Doing so allows a plausible reason for asking about services, policies, and software that's running in an environment. The adversary can then send malicious links or attachments through these services.

A common example is to build rapport with a target via social media, then send content to a personal webmail service that the target uses on their work computer. This allows an adversary to bypass some email restrictions on the work account, and the target is more likely to open the file since it's something they were expecting. If the payload doesn't work as expected, the adversary can continue normal communications and troubleshoot with the target on how to get it working.

EnterpriseT1566.003Sub-techniqueObject v2.0 Modified
Glexia's Take

Analyst context for executives and security teams

Analyst confidence High

Spearphishing via Service matters because it moves the initial-access conversation outside the enterprise email stack. An employee may be approached through social media, personal webmail, or another third-party service, build trust with the sender, and then open a link or attachment on a Windows, macOS, or Linux work system. The business risk is that controls and evidence built only around corporate email may miss the interaction that led to compromise.

Executive priority

Treat this as a test of whether phishing defense is limited to the email gateway or covers the way employees actually communicate. Leaders should ask whether acceptable-use policy, user training, web controls, endpoint protection, audit logging, and account privilege controls still work when the lure arrives through non-enterprise services. The number of ATT&CK relationships to campaigns and groups indicates this behavior is broadly relevant across espionage and financially motivated contexts, but local risk depends on workforce exposure and telemetry.

Technical view

This is an initial-access sub-technique of Phishing for Linux, macOS, and Windows environments. MITRE does not provide official detection text for this object, but it is related to DET0115, a detection strategy for spearphishing via a service across OS platforms. SOC and IR teams should validate visibility around third-party web services, personal webmail usage from managed endpoints, downloaded attachments, clicked links, endpoint execution, and subsequent authentication or account activity. Detection should focus less on corporate email headers and more on the chain from off-channel message to browser access, file download, execution, and identity use.

Likely telemetry

  • Web proxy, secure web gateway, URL filtering, or DNS logs showing access to social media, personal webmail, file-sharing, or other third-party services
  • Browser and download history or endpoint telemetry for files retrieved from non-enterprise services
  • Endpoint antivirus/antimalware or EDR alerts for malicious attachments, links, payload execution, or suspicious child processes
  • Audit logs from managed systems showing user activity around downloads, file opens, and execution events
  • Identity and user account logs showing suspicious sign-ins, privilege use, or account activity after a reported interaction

Detection direction

  • Validate that phishing triage workflows accept and investigate reports from social media, personal webmail, and other third-party services, not only corporate email submissions.
  • Tune detections for suspicious web downloads and endpoint execution following access to non-enterprise messaging or webmail services; account for legitimate recruiting, sales, support, and professional networking activity as likely false-positive drivers.
  • Confirm whether logs from web controls, endpoint controls, and audits can be correlated by user and device across Windows, macOS, and Linux systems.
  • Look for blind spots where personal webmail, unmanaged browsers, encrypted web traffic, or privacy restrictions prevent reconstruction of the initial-access path.
  • Use relationship context carefully: multiple groups and one campaign are linked to this technique, but those relationships should guide threat-informed validation rather than imply current activity in a specific environment.

Mitigation priorities

  • Prioritize user training that explicitly covers off-channel social engineering, including rapport-building through social media, personal webmail, job opportunities, and requests to open files or links on work devices.
  • Apply user account management and least privilege so a successful lure has reduced ability to expand access through the compromised user context.
  • Restrict risky web-based content where appropriate, including unsafe downloads, malicious sites, and unauthorized browser behaviors, while balancing business use of legitimate third-party services.
  • Maintain antivirus/antimalware coverage across managed endpoints and ensure detections are updated and monitored.
  • Use auditing to preserve evidence needed for incident response and compliance review, including endpoint, web access, and account activity logs.
Analyst notes and limits

The key defensive lesson is channel displacement: the adversary may avoid enterprise email controls by using services the organization does not own. This makes user reporting, endpoint visibility, web access telemetry, and identity monitoring decisive. ATT&CK relationships include Operation Dream Job and multiple groups such as APT29, Lazarus Group, FIN6, OilRig, Dark Caracal, EXOTIC LILY, CURIUM, ToddyCat, Moonstone Sleet, Storm-1811, and Contagious Interview, supporting threat-informed prioritization without proving local exposure.

MITRE provides no official detection text for this object in the supplied fields. Telemetry and control recommendations are inferred from the official description, platforms, tactic, external references, and mitigation/detection relationships. Effectiveness depends on local policy, logging, endpoint management, web control coverage, and whether employees use third-party services from work systems.

Official MITRE ATT&CK definition

Spearphishing via Service

Adversaries may send spearphishing messages via third-party services in an attempt to gain access to victim systems. Spearphishing via service is a specific variant of spearphishing. It is different from other forms of spearphishing in that it employs the use of third party services rather than directly via enterprise email channels.

All forms of spearphishing are electronically delivered social engineering targeted at a specific individual, company, or industry. In this scenario, adversaries send messages through various social media services, personal webmail, and other non-enterprise controlled services.[1] These services are more likely to have a less-strict security policy than an enterprise. As with most kinds of spearphishing, the goal is to generate rapport with the target or get the target's interest in some way. Adversaries will create fake social media accounts and message employees for potential job opportunities. Doing so allows a plausible reason for asking about services, policies, and software that's running in an environment. The adversary can then send malicious links or attachments through these services.

A common example is to build rapport with a target via social media, then send content to a personal webmail service that the target uses on their work computer. This allows an adversary to bypass some email restrictions on the work account, and the target is more likely to open the file since it's something they were expecting. If the payload doesn't work as expected, the adversary can continue normal communications and troubleshoot with the target on how to get it working.

View the same entry on attack.mitre.org (MITRE-hosted reference; in-page links above use the Glexia ATT&CK library.)

Glexia analysis

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.

ATT&CK relationship table

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.

2 rows
Domain ID Name Relationship / procedure
Enterprise T1194 Spearphishing via Service Spearphishing via Service revoked by this object.
Enterprise T1566 Phishing This object subtechnique of Phishing.
Associated objects

Groups, software, and campaigns

Group Enterprise

G1012: CURIUM

CURIUM is an Iranian threat group, first reported in September 2019 and active since at least July 2018, targeting IT service providers in the Middle East.[1] CURIUM has since invested in building relationships with potential targets via social media over a period of months to establish trust and confidence before sending malware. Security researchers note CURIUM has demonstrated great patience and persistence by chatting with potential targets daily and sending benign files to help lower their security consciousness.[2]

Group Enterprise

G0112: Windshift

Windshift is a threat group that has been active since at least 2017, targeting specific individuals for surveillance in government departments and critical infrastructure across the Middle East.[1][2][3]

Group Enterprise

G0130: Ajax Security Team

Ajax Security Team is a group that has been active since at least 2010 and believed to be operating out of Iran. By 2014 Ajax Security Team transitioned from website defacement operations to malware-based cyber espionage campaigns targeting the US defense industrial base and Iranian users of anti-censorship technologies.[1]

Group Enterprise

G1011: EXOTIC LILY

EXOTIC LILY is a financially motivated group that has been closely linked with Wizard Spider and the deployment of ransomware including Conti and Diavol. EXOTIC LILY may be acting as an initial access broker for other malicious actors, and has targeted a wide range of industries including IT, cybersecurity, and healthcare since at least September 2021.[1]

Group Enterprise

G1022: ToddyCat

ToddyCat is a sophisticated threat group that has been active since at least 2020 using custom loaders and malware in multi-stage infection chains against government and military targets across Europe and Asia.[1][2]

Group Enterprise

G0037: FIN6

FIN6 is a cyber crime group that has stolen payment card data and sold it for profit on underground marketplaces. This group has aggressively targeted and compromised point of sale (PoS) systems in the hospitality and retail sectors.[1][2]

Group Enterprise

G0016: APT29

APT29 is threat group that has been attributed to Russia's Foreign Intelligence Service (SVR).[1][2] They have operated since at least 2008, often targeting government networks in Europe and NATO member countries, research institutes, and think tanks. APT29 reportedly compromised the Democratic National Committee starting in the summer of 2015.[3][4][5][6]

In April 2021, the US and UK governments attributed the SolarWinds Compromise to the SVR; public statements included citations to APT29, Cozy Bear, and The Dukes.[7][8] Industry reporting also referred to the actors involved in this campaign as UNC2452, NOBELIUM, StellarParticle, Dark Halo, and SolarStorm.[9][10][11][12][13][14]

Group Enterprise

G0049: OilRig

OilRig is a suspected Iranian threat group that has targeted Middle Eastern and international victims since at least 2014. The group has targeted a variety of sectors, including financial, government, energy, chemical, and telecommunications. It appears the group carries out supply chain attacks, leveraging the trust relationship between organizations to attack their primary targets. The group works on behalf of the Iranian government based on infrastructure details that contain references to Iran, use of Iranian infrastructure, and targeting that aligns with nation-state interests.[1][2][3][4][5][6][7]

Group Enterprise

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]

Group Enterprise

G1046: Storm-1811

Storm-1811 is a financially-motivated entity linked to Black Basta ransomware deployment. Storm-1811 is notable for unique phishing and social engineering mechanisms for initial access, such as overloading victim email inboxes with non-malicious spam to prompt a fake "help desk" interaction leading to the deployment of adversary tools and capabilities.[1][2][3][4]

Malware Enterprise

S1100: Ninja

Ninja is a malware developed in C++ that has been used by ToddyCat to penetrate networks and control remote systems since at least 2020. Ninja is possibly part of a post exploitation toolkit exclusively used by ToddyCat and allows multiple operators to work simultaneously on the same machine. Ninja has been used against government and military entities in Europe and Asia and observed in specific infection chains being deployed by Samurai.[1]

Windows
Campaign Enterprise

C0022: Operation Dream Job

Operation Dream Job was a cyber espionage operation likely conducted by Lazarus Group that targeted the defense, aerospace, government, and other sectors in the United States, Israel, Australia, Russia, and India. In at least one case, the cyber actors tried to monetize their network access to conduct a business email compromise (BEC) operation. In 2020, security researchers noted overlapping TTPs, to include fake job lures and code similarities, between Operation Dream Job, Operation North Star, and Operation Interception; by 2022 security researchers described Operation Dream Job as an umbrella term covering both Operation Interception and Operation North Star.[1][2][3][4]

Relationship explorer

All related ATT&CK context

Mitigations

Mitigation direction

Change history

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 .

ATT&CK release
19.1
Object version
2.0
Created
Modified
Raw hash
7c51607cb5116fa5...
Imported snapshots across ATT&CK releases (1)
Release Bundle imported Object version Modified Status Raw hash
19.1 2.0 Current bundle 7c51607cb511…
Raw source

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.

Source references

External references and citations

MITRE external references are preserved separately from Glexia analysis so citations remain traceable to their original source records.

  1. [1]
    Lookout Dark Caracal Jan 2018

    Blaich, A., et al. (2018, January 18). Dark Caracal: Cyber-espionage at a Global Scale. Retrieved April 11, 2018.

    Open source URL
  2. [2]
    mitre-attack T1566.003
    Open source URL
Source and licensing

Source: MITRE ATT&CK®. © 2026 The MITRE Corporation. This work is reproduced and distributed with the permission of The MITRE Corporation. MITRE ATT&CK and ATT&CK are registered trademarks of The MITRE Corporation. Glexia is not affiliated with or endorsed by MITRE.