Microsoft warns of “massive campaign” using COVID-19 themed emails

Experts from the Microsoft Security Intelligence team provided some details on a new “massive campaign” using COVID-19 themed emails.

Researchers from the Microsoft Security Intelligence team provided some details on a new massive phishing campaign using COVID-19 themed emails.

The messages used weaponized Excel documents, the IT giant observed a spike in the number of malicious documents in malspam campaigns which use Excel 4.0 macros.

“For several months now, we’ve been seeing a steady increase in the use of malicious Excel 4.0 macros in malware campaigns. In April, these Excel 4.0 campaigns jumped on the bandwagon and started using COVID-19 themed lures.” states Microsoft in a Tweet.

The latest COVID-19 campaign began in April, the messages purport to be from the Johns Hopkins Center and use an Excel attachment. Once opened the attachment, it will show a graph of Coronavirus cases in the United States and trick the victims into enabling the macros to start the infection.

The macros drop a remote access tool (RAT) named NetSupport Manager, it is a legitimate application that is abused by attackers to take control over victim systems.

“The hundreds of unique Excel files in this campaign use highly obfuscated formulas, but all of them connect to the same URL to download the payload. NetSupport Manager is known for being abused by attackers to gain remote access to and run commands on compromised machines.” continues Microsoft.

The NetSupport RAT employed in this COVID-19-themed campaign also drops multiple components, including several .dll, .ini, and other .exe files, a VBScript, and an obfuscated PowerSploit-based PowerShell script. Then it connects to a command and control server, allowing threat actors to send further commands.

Below the Indicators of Compromise (IoCs) shared by Microsoft:

Below a list or recommendations to avoid this threat:

Keep your anti-virus software up to date.
Search for existing signs of the threat using IoCs in your environment.
Keep applications and operating systems running and up to date.
Be vigilant with attachments and links in emails.

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Pierluigi Paganini

(SecurityAffairs – COVID-19, hacking)

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Pierluigi Paganini

Pierluigi Paganini is member of the ENISA (European Union Agency for Network and Information Security) Threat Landscape Stakeholder Group and Cyber G7 Group, he is also a Security Evangelist, Security Analyst and Freelance Writer. Editor-in-Chief at "Cyber Defense Magazine", Pierluigi is a cyber security expert with over 20 years experience in the field, he is Certified Ethical Hacker at EC Council in London. The passion for writing and a strong belief that security is founded on sharing and awareness led Pierluigi to find the security blog "Security Affairs" recently named a Top National Security Resource for US. Pierluigi is a member of the "The Hacker News" team and he is a writer for some major publications in the field such as Cyber War Zone, ICTTF, Infosec Island, Infosec Institute, The Hacker News Magazine and for many other Security magazines. Author of the Books "The Deep Dark Web" and “Digital Virtual Currency and Bitcoin”.