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Abnormal Intelligence

Credential Phishing

Phishing Attack Uses Compromised Account to Send Text-Free Email with Link to PDF Hosted on SharePoint

Threat actor sends fraudulent notification of online fax containing purchase order for review to compel target to view PDF containing phishing link.

November 4, 2024

Attack Target Summary

  • Type: Credential Phishing
  • Industry: Facilities Management
  • Recipient: Service Delivery Manager
  • Attack Vector: Link-based

Attack Overview

Step 1: Email (Fake Purchase Order from Vendor Sent via Online Fax Service)

AI Text Free Email Linked to PDF Hosted on Share Point Email
  • Sent from a legitimate compromised account
  • Body of email is embedded image, not text
  • Image contains link to SharePoint site
AI Text Free Email Linked to PDF Hosted on Share Point Share Point PDF
  • PDF hosted on legitimate SharePoint site
  • File contains link purportedly to view shared document
  • “Open Document” button linked to spoofed Microsoft portal

Step 3: Final Destination

AI Text Free Email Linked to PDF Hosted on Share Point Microsoft
  • Phishing page designed to mimic Microsoft login screen
  • Any information entered will be stolen by attacker

How Does This Attack Bypass Email Defenses?

This email attack bypasses traditional security solutions for several reasons, including:

  • Compromised Email: Attacker uses a legitimate, compromised account.
  • No Malicious Attachments: Images contain links leading to seemingly harmless PDF.
  • Legitimate Links: PDF was hosted on a legitimate SharePoint site.

How Did Abnormal Detect This Attack?

This attack was detected using AI and ML by analyzing various factors, including:

  • Unknown Sender: Recipient has had no previous correspondence with sender.
  • Suspicious Link Analysis: Abnormal detects suspicious links in the email body.
  • Unusual Sender Domain: Sender domain doesn’t match any domains found in body links.

By recognizing established normal behavior and detecting these abnormal indicators, a modern email security solution has the ability to prevent this attack from reaching inboxes.

Please note the exact detection mechanism from Abnormal Security's system might include proprietary techniques and methodologies not disclosed here.

Classification

Credential PhishingLink-basedExternal Party - Vendor/SupplierCredential Theft

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