EMAIL BETA - Email mimics replies or forwards without an actual ongoing conversation

Cortex XDR Analytics Alert Reference by data source

Product
Cortex XDR
Last date published
2025-04-07
Category
Analytics Alert Reference
Index by
data source

Synopsis

Activation Period

14 Days

Training Period

30 Days

Test Period

N/A (single event)

Deduplication Period

1 Day

Required Data

  • Requires:
    • Office 365 Mail

Detection Modules

Email

Detector Tags

ATT&CK Tactic

Initial Access (TA0001)

ATT&CK Technique

Severity

Low

Description

An email with a subject line or body that includes signs of a reply or forward without an actual ongoing conversation.

Attacker's Goals

Create the illusion of being part of an existing email conversation to build trust and reduce the target's suspicion, mislead recipients by concealing harmful intents such as phishing or malware distribution.

Investigative actions

  • Analyze the full set of email headers to confirm the absence of legitimate References and In-Reply-To headers and verify if the email was altered or forged.
  • Investigate if the sender's domain is known, flagged, or associated with suspicious activity to detect possible impersonation.
  • If the message contains attachments/links, scrutinize them for any suspicious indications.
  • Monitor further actions taken, such as file downloads or access to potentially malicious links.