T1534: Internal Spearphishing
After they already have access to accounts or systems within the environment, adversaries may use internal spearphishing to gain access to additional information or compromise other users within the same organization. Internal spearphishing is multi-staged campaign where a legitimate account is initially compromised either by controlling the user's device or by compromising the account credentials of the user. Adversaries may then attempt to take advantage of the trusted internal account to increase the likelihood of tricking more victims into falling for phish attempts, often incorporating Impersonation.
For example, adversaries may leverage Spearphishing Attachment or Spearphishing Link as part of internal spearphishing to deliver a payload or redirect to an external site to capture credentials through Input Capture on sites that mimic login interfaces.
Adversaries may also leverage internal chat apps, such as Microsoft Teams, to spread malicious content or engage users in attempts to capture sensitive information and/or credentials.
How it's found
Internal Spearphishing via Trusted Accounts: Sequence of internal email sent from a recently compromised user account (preceded by abnormal logon or device activity), with attachments or links leading to execution or credential harvesting. Defender observes: internal mail delivery to peers with high entropy attachments, followed by click events, process initiation, or credential prompts. Delivery of suspicious internal communication (e.g., Thunderbird, Evolution) using compromised internal accounts. Sequence of: unexpected user activity + mail transfer logs + download or execution of attachments. Abnormal Apple Mail use, including internal email relays followed by file execution or script events (e.g., attachments launched via Preview, terminal triggered from Mail.app) Internal spearphishing via SaaS applications (e.g., Slack, Teams, Gmail): message sent from compromised user with attachment or URL, followed by click and credential access behavior. Outlook or Word used to forward suspicious internal attachments with macro content. Defender observes attachment forwarding, auto-opening behaviors, or macro prompt interactions.
Standards mapping
Where this fits in a TurboPentest engagement
This weakness is not covered by the automated black-box pentest. IntegSec pentesters cover it in a manual engagement.
Frequently asked questions
What is T1534 Internal Spearphishing?
After they already have access to accounts or systems within the environment, adversaries may use internal spearphishing to gain access to additional information or compromise other users within the same organization. Internal spearphishing is multi-staged campaign where a legitimate account is initially compromised either by controlling the user's device or by compromising the account credentials of the user. Adversaries may then attempt to take advantage of the trusted internal account to increase the likelihood of tricking more victims into falling for phish attempts, often incorporating Impersonation. For example, adversaries may leverage Spearphishing Attachment or Spearphishing Link as part of internal spearphishing to deliver a payload or redirect to an external site to capture credentials through Input Capture on sites that mimic login interfaces. Adversaries may also leverage internal chat apps, such as Microsoft Teams, to spread malicious content or engage users in attempts to capture sensitive information and/or credentials.
Which tactics does T1534 belong to?
T1534 maps to the Lateral Movement tactic.
Does TurboPentest test for Internal Spearphishing?
This weakness is not covered by the automated black-box pentest. IntegSec pentesters cover it in a manual engagement.
Related MITRE ATT&CK techniques
- Lateral MovementT1021: Remote Services
- Execution, Lateral MovementT1072: Software Deployment Tools
- Lateral MovementT1080: Taint Shared Content
- Initial Access, Lateral MovementT1091: Replication Through Removable Media
- Lateral MovementT1210: Exploitation of Remote Services
- Lateral MovementT1550: Use Alternate Authentication Material
About this reference
These security references are maintained by IntegSec, an offensive-security firm whose team holds CISSP, OSCP, and OSCE certifications and has run thousands of penetration tests. Content is kept current as tools, standards, and attack techniques evolve.
Find these issues before an attacker does
TurboPentest runs an agentic AI pentest against your target and reports findings with proof, from $99 per target.
Start a pentest