Exchange inbox forwarding rule configured

Cortex XDR Analytics Alert Reference by Alert name

Product
Cortex XDR
Last date published
2024-06-04
Category
Analytics Alert Reference
Order
Alert name

Synopsis

Activation Period

14 Days

Training Period

30 Days

Test Period

N/A (single event)

Deduplication Period

1 Day

Required Data

  • Requires:
    • Office 365 Audit

Detection Modules

Identity Threat Module

ATT&CK Tactic

ATT&CK Technique

Severity

Informational

Description

A user configured an Exchange inbox forwarding rule, which forwards emails that meet specific conditions.

Attacker's Goals

Create an inbox rule using a compromised user account to automatically forward emails containing specific conditions to an external recipient.

Investigative actions

  • Check what conditions are met in the inbox rule (e.g. specific keywords in the subject or body).
  • Determine if any of the conditions and keywords look suspicious.
  • Look for signs that the user account and mailbox are compromised (e.g. abnormal logins, unusual activity).
  • Check if the forwarding domain is an unknown external domain and look up its reputation.
  • Investigate the IP address associated with the rule.
  • Follow further actions done by the account.
  • Check for a possible phishing campaign on the organization.
  • Look for emails sent to this recipient by other users.

Variations

Exchange inbox forwarding rule configured by a delegate user

Synopsis

ATT&CK Tactic

ATT&CK Technique

Severity

Informational

Description

A user configured an Exchange inbox forwarding rule, which forwards emails that meet specific conditions. The user who set the forwarding is a delegated user, who performed this action on behalf of another user.

Attacker's Goals

Create an inbox rule using a compromised user account to automatically forward emails containing specific conditions to an external recipient.

Investigative actions

  • Check what conditions are met in the inbox rule (e.g. specific keywords in the subject or body).
  • Determine if any of the conditions and keywords look suspicious.
  • Look for signs that the user account and mailbox are compromised (e.g. abnormal logins, unusual activity).
  • Check if the forwarding domain is an unknown external domain and look up its reputation.
  • Investigate the IP address associated with the rule.
  • Follow further actions done by the account.
  • Check for a possible phishing campaign on the organization.
  • Look for emails sent to this recipient by other users.


Suspicious Exchange inbox forwarding rule configured

Synopsis

ATT&CK Tactic

ATT&CK Technique

Severity

Medium

Description

A user configured an Exchange inbox forwarding rule, which forwards emails that meet specific conditions.

Attacker's Goals

Create an inbox rule using a compromised user account to automatically forward emails containing specific conditions to an external recipient.

Investigative actions

  • Check what conditions are met in the inbox rule (e.g. specific keywords in the subject or body).
  • Determine if any of the conditions and keywords look suspicious.
  • Look for signs that the user account and mailbox are compromised (e.g. abnormal logins, unusual activity).
  • Check if the forwarding domain is an unknown external domain and look up its reputation.
  • Investigate the IP address associated with the rule.
  • Follow further actions done by the account.
  • Check for a possible phishing campaign on the organization.
  • Look for emails sent to this recipient by other users.


External Exchange inbox forwarding rule configured

Synopsis

ATT&CK Tactic

ATT&CK Technique

Severity

Low

Description

A user configured an Exchange inbox forwarding rule, which forwards emails that meet specific conditions. The rule forwards emails to a public domain, which may be a sign of compromise.

Attacker's Goals

Create an inbox rule using a compromised user account to automatically forward emails containing specific conditions to an external recipient.

Investigative actions

  • Check what conditions are met in the inbox rule (e.g. specific keywords in the subject or body).
  • Determine if any of the conditions and keywords look suspicious.
  • Look for signs that the user account and mailbox are compromised (e.g. abnormal logins, unusual activity).
  • Check if the forwarding domain is an unknown external domain and look up its reputation.
  • Investigate the IP address associated with the rule.
  • Follow further actions done by the account.
  • Check for a possible phishing campaign on the organization.
  • Look for emails sent to this recipient by other users.