Possible phishing attack via Microsoft Teams

Cortex XDR Analytics Alert Reference by Alert name

Product

Cortex XDR

Last date published

2026-05-18

Synopsis

Activation Period	14 Days
Training Period	30 Days
Test Period	5 Hours
Deduplication Period	1 Day
Required Data	Requires: Azure Audit Log Requires: AzureAD Requires: AzureAD Audit Log Requires: Microsoft Graph Logs Requires: Office 365 Audit Requires: Okta Requires: Okta Audit Log Requires one of the following data sources: Palo Alto Networks Firewall EAL Logs OR Palo Alto Networks Firewall threat Logs Requires one of the following data sources: Palo Alto Networks Global Protect OR Third-Party VPNs Requires: XDR Agent Requires: XDR Agent with eXtended Threat Hunting (XTH)
Detection Modules	Identity Threat Module
Detector Tags	Microsoft Teams
ATT&CK Tactic	Initial Access (TA0001)
ATT&CK Technique	Phishing (T1566)
Severity	Low

Description

An external tenant is possibly attempting a phishing attack via Microsoft Teams.

Attacker's Goals

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

Investigative actions

Verify the suspicious sign-in activity to validate the legitimacy of the suspicious login.
Review Teams chat logs and meeting invites for interactions with external tenants, focusing on unusual file sharing or unsolicited links.
Hunt for known phishing indicators (suspicious domains, URL patterns, or IPs) in the Teams messages and linked content.
Evaluate the external tenant reputation.
Check for anomalous MS Teams actions like suspicious application installation, message extraction, policy changes or internal spear phishing attempts linked to the user post-login.
Follow further actions done by the account.

Variations

Potential phishing attack with post compromise stages had been detected

Synopsis

ATT&CK Tactic	Initial Access (TA0001)
ATT&CK Technique	Phishing (T1566)
Severity	High

Description

Suspicious Microsoft Teams phishing activity detected across multiple indicators, the activities have strong indications of a malicious login and post compromise actions.

Attacker's Goals

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

Investigative actions

Verify the suspicious sign-in activity to validate the legitimacy of the suspicious login.
Review Teams chat logs and meeting invites for interactions with external tenants, focusing on unusual file sharing or unsolicited links.
Hunt for known phishing indicators (suspicious domains, URL patterns, or IPs) in the Teams messages and linked content.
Evaluate the external tenant reputation.
Check for anomalous MS Teams actions like suspicious application installation, message extraction, policy changes or internal spear phishing attempts linked to the user post-login.
Follow further actions done by the account.

Potential phishing attack via Microsoft Teams has been detected

Synopsis

ATT&CK Tactic	Initial Access (TA0001)
ATT&CK Technique	Phishing (T1566)
Severity	Medium

Description

Suspicious Microsoft Teams phishing activity detected across multiple indicators, the activities have strong indications of a malicious login.

Attacker's Goals

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

Investigative actions

Verify the suspicious sign-in activity to validate the legitimacy of the suspicious login.
Review Teams chat logs and meeting invites for interactions with external tenants, focusing on unusual file sharing or unsolicited links.
Hunt for known phishing indicators (suspicious domains, URL patterns, or IPs) in the Teams messages and linked content.
Evaluate the external tenant reputation.
Check for anomalous MS Teams actions like suspicious application installation, message extraction, policy changes or internal spear phishing attempts linked to the user post-login.
Follow further actions done by the account.

Potential phishing attack with post compromise activities in Microsoft Teams has been detected

Synopsis

ATT&CK Tactic	Initial Access (TA0001)
ATT&CK Technique	Phishing (T1566)
Severity	Medium

Description

Suspicious Microsoft Teams phishing activity detected across multiple indicators.

Attacker's Goals

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

Investigative actions

Verify the suspicious sign-in activity to validate the legitimacy of the suspicious login.
Review Teams chat logs and meeting invites for interactions with external tenants, focusing on unusual file sharing or unsolicited links.
Hunt for known phishing indicators (suspicious domains, URL patterns, or IPs) in the Teams messages and linked content.
Evaluate the external tenant reputation.
Check for anomalous MS Teams actions like suspicious application installation, message extraction, policy changes or internal spear phishing attempts linked to the user post-login.
Follow further actions done by the account.