External user added a link to a Microsoft Teams chat

Synopsis

Field	Value
Activation Period	14 Days
Training Period	30 Days
Test Period	N/A (single event)
Deduplication Period	1 Day
Required Data	Office 365 Audit
Detection Modules	Identity Threat Module, SaaS Threat Detection
Detector Tags	Microsoft Teams
ATT&CK Tactic	Initial Access (TA0001)
ATT&CK Technique	Phishing (T1566)
Severity	Informational

Description

An external user added a link to a Microsoft Teams chat.

Attacker's Goals

Attackers may leverage Microsoft Teams to conduct phishing attacks by exploiting trusted communication channels with users inside the organization.

Investigative actions

• Confirm that the external tenant and user are authorized to share links or files with users in the organization.
• Verify the content of the conversation and validate that there is no phishing attempt being made.
• Inspect links and URLs that have been sent in the conversation.
• Evaluate the external domain reputation.
• Review past communication from the external user.
• Follow further actions done by the account.

Variations

An external user sent a link via Microsoft Teams with suspicious parameters

Synopsis

Field	Value
ATT&CK Tactic	Initial Access (TA0001)
ATT&CK Technique	Phishing (T1566)
Severity	Low

Description

An external user sent a link with suspicious parameters in a Microsoft Teams conversation.

Attacker's Goals

Attackers may leverage Microsoft Teams to conduct phishing attacks by exploiting trusted communication channels with users inside the organization.

Investigative actions

• Confirm that the external tenant and user are authorized to share links or files with users in the organization.
• Verify the content of the conversation and validate that there is no phishing attempt being made.
• Inspect links and URLs that have been sent in the conversation.
• Evaluate the external domain reputation.
• Review past communication from the external user.
• Follow further actions done by the account.