Trustwave SpiderLabs Uncovers Critical Cybersecurity Vulnerabilities Exposing Manufacturers to Costly Attacks. Learn More

Trustwave SpiderLabs Uncovers Critical Cybersecurity Vulnerabilities Exposing Manufacturers to Costly Attacks. Learn More

Managed Detection & Response

Eradicate cyberthreats with world-class intel and expertise

Managed Security Services

Expand your team’s capabilities and strengthen your security posture

Consulting & Professional Services

Tap into our global team of tenured cybersecurity specialists

Penetration Testing

Subscription- or project-based testing, delivered by global experts

Database Security

Get ahead of database risk, protect data and exceed compliance requirements

Email Security & Management

Catch email threats others miss with layered security & maximum control

Co-Managed SOC (SIEM)

Eliminate alert fatigue, focus your SecOps team, stop threats fast, and reduce cyber risk

Microsoft Exchange Server Attacks
Stay protected against emerging threats
Rapidly Secure New Environments
Security for rapid response situations
Securing the Cloud
Safely navigate and stay protected
Securing the IoT Landscape
Test, monitor and secure network objects
Why Trustwave
The Trustwave Approach
Awards and Accolades
Trustwave SpiderLabs Team
Trustwave Fusion Platform
SpiderLabs Fusion Center
Security Operations Centers
Technology Alliance Partners
Key alliances who align and support our ecosystem of security offerings
Trustwave PartnerOne Program
Join forces with Trustwave to protect against the most advance cybersecurity threats
SpiderLabs Blog

Emotet lives another day using Fake O2 invoice notifications

We witnessed a widespread phishing campaign targeting O2 customers, that surfaced on 18th August, 2017 and continued intermittently until 21st August, 2017. Telefonica UK Limited, trading as O2, is a major telco provider in the UK. In this campaign scammers sent out fake O2 invoice emails as spam. These spam phishing emails contained links to malicious Microsoft Word documents, that in turn infected victims with a banking trojan. The attack flow is shown here:



Analysis of the Email

The scammers used spoofed email addresses in the email "From" field and sent out the same emails using one of the two subject lines:

  1. Subject: My O2 Business - Your O2 Bill is ready
  2. Subject: Your O2 bill is ready - (Victims Name)

The fake email message appears as a legit automated O2 bill invoice, that encourages the victims to click on the link to "View Billing Statement" as shown in Figure 1 and 2.


Figure 1: O2 Phishing email message


Figure 2: O2 phishing invoice messages pointing to malicious word document


Analysis of the Phishing link and the Malicious Word document:

Clicking on the link points the web browser to the Phishing site: (see Figure 3). The link appears to be hosted on a compromised web site, that downloads a malicious Word document "O2 bill - 805985874058.doc" (MD5: 2E8BBD0C8B7DE7D5F4E541C192421451). This word document contains a malicious obfuscated macro (see Figure 4):


Figure 3: Malicious word document download via HTTP


Figure 4: Malicious Macro


The macro executes a base 64 encoded Powershell command (see Figure 5).

Figure 5: Encoded Powershell command used by Macro


A decoded version of the command is show in Figure 6.

Figure 6: Decoded version of the Powershell command


Opening the macro enabled word document, launches the Powershell script, that downloads and executes a malware sample from the URL: hxxp://wernerbernheim(.)com(.)uy/capacitacion/bMLTBrcIE/

The downloaded malware is saved to: C:\Users\{user}\AppData\Local\Temp\{random}.exe , having MD5: D6EDE359E1ECBF8248B0FC8EF63CED7E .

Analysis of the Malware:

The downloaded malware is a variant of the Emotet malware. Emotet is a notorious multi-faceted banking trojan that rolls out different behaviors such as:

  • Info stealing module - emails, PST, browsers
  • Email spamming modules
  • Denial of service module

Depending on the module behavior, it drops a malware component to the following path:

  • %WINDIR%\system32\dcomevent.exe
  • %LOCALAPPDATA%\Microsoft\Windows\dcomevent.exe

For persistence, it creates the following registry keys:

  • HKLM\SYSTEM\CurrentControlSet\services\dcomevent
  • HKCU\Software\Microsoft\Windows\CurrentVersion\Run

It also tries to connect to its CnC server at IP using HTTPS (see Figure 7).

Figure 7: HTTP traffic


The malware then loads its spam module and attempts to send out new spam/phishing emails to thousands of email addresses (see Figure 8). This is a typical spambot behavior, where first it performs DNS lookups on each target email domain and then sends the spam to the respective SMTP server for that domain.

Figure 8: A snapshot of the SMTP traffic used by the malware to send out spam


Following the link provided in the spammed email downloads the same malicious word document file, but this time hosted on a different domain (see Figure 9).

Figure 9: Link to malicious Word document sent out as spam by the malware


Indicators of Compromise (IOCs)

  • URL in the Email:
    • hxxp://marianamengote(.)com/RLDXAIYKZD2314573/
  • Malicious Word Document:
    • FileName: "O2 bill - 805985874058.doc"
    • MD5: 2E8BBD0C8B7DE7D5F4E541C192421451
  • URL to download Emotet:
  • Emotet variant:
    • MD5: D6EDE359E1ECBF8248B0FC8EF63CED7E
    • C2: 39.95.185


Attackers are leveraging the simplicity provided by the email infrastructure to distribute banking trojans to global victims. We observed one such targeted phishing campaign delivering counterfeit emails claiming to come from O2, a UK based telecom company. The legitimate-looking messages pretend to be dispatching a billing invoice, but the link included leads to a malicious Word document file. Upon opening the document it attempts to install a variant of the notorious Emotet banking Trojan. This variant is equipped with a spamming module that starts sending out spam messages containing infected links to email addresses globally. This type of attack flow (Spam->contains-malicious-link->downloads-malicious-document->downloads-and-executes-Trojan) appears to be on an increase on the threat landscape, likely as a measure to evade email gateways. Additionally, malware equipped with spamming modules used in such campaigns is designed to perpetuate the attack. As a mitigation measure, customers should avoid opening any email messages that appear suspicious, especially avoid opening any unexpected office documents containing macros.


We would like to thank Phil Hay for his valuable advice and guidance.

Latest SpiderLabs Blogs

Trustwave SpiderLabs Report: LockBit 3.0 Ransomware Vs. the Manufacturing Sector

As the manufacturing sector continues its digital transformation, Operational Technology (OT), Industrial Control Systems (ICS), and Supervisory Control and Data Acquisition (SCADA) are becoming...

Read More

Overview of the Cyberwarfare used in Israel – Hamas War

On October 7, 2023, the Palestinian organization Hamas launched the biggest attack on Israel in years, resulting in numerous casualties and hostages taken. Israel responded with a large-scale ground...

Read More

The 2023 Retail Services Sector Threat Landscape: A Trustwave Threat Intelligence Briefing

The annual holiday shopping season is poised for a surge in spending, a fact well-known to retailers, consumers, and cybercriminals alike. The latter group, however, is poised to exploit any...

Read More