The Emotet botnet is back and hits 100K recipients per day

Emotet is back on Christmas Eve, cybercrime operators are sending out spam messages to deliver the infamous Trickbot Trojan.

Emotet is back on Christmas Eve, after two months of silence, cybercrime operators are sending out spam messages to deliver the infamous Trickbot Trojan.

The recent Emotet campaign uses updated payloads and is targeting over 100,000 recipients per day.

“After a lull of nearly two months, the Emotet botnet has returned with updated payloads. The changes are likely meant to help Emotet avoid detection both by victims and network defenders.” reads the post published by Cofense. “Apart from these updates, the campaigns’ targeting, tactics and secondary payloads remain consistent with previous active periods.”

The Emotet banking trojan has been active at least since 2014, the botnet is operated by a threat actor tracked as TA542. In the middle-August, the malware was employed in fresh COVID19-themed spam campaign

Recent spam campaigns used messages with malicious Word documents, or links to them, pretending to be an invoice, shipping information, COVID-19 information, resumes, financial documents, or scanned documents.

The infamous banking trojan is also used to deliver other malicious code, such as Trickbot and QBot trojan or ransomware such as Conti (TrickBot) or ProLock (QBot).

Emotet is a modular malware, its operators could develop new Dynamic Link Libraries to update its capabilities.

In October, the Cybersecurity and Infrastructure Security Agency (CISA) issued an alert to warn of a surge of Emotet attacks that have targeted multiple state and local governments in the U.S. since August.

While in October the botnet was mainly using TrickBot, Qakbot and ZLoader as secondary payloads, today Cofense researchers observed TrickBot,

The TrickBot malware has been active since 2016, it was continuously updated to implement new features and avoid detection.

TrickBot allows attackers to gather information from compromised systems, it also attempts to make lateral movements to infect other machines on the same network. Then the attackers attempt to monetize their efforts by deploying other payloads, like the Ryuk Ransomware

Experts pointed out that the new Emotet campaign includes a noticeable change to avoid raising suspicion. The spam messages use a document that contains a malicious macro to install Emotet, and still claim to be a “protected” document that requires users to enable macros in order to open it. Unlike older versions, the new one creates a dialog box saying that “Word experienced an error trying to open the file.” This trick gives the user an explanation of why they don’t see the expected content.

Proofpoint researchers also observed the same campaign using messages in English, German, Spanish, Italian and more.

“Emotet’s active periods have been unpredictable, and its authors have made an effort to adapt both the email campaigns and the malware to spread more effectively.” concludes Cofense.

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Pierluigi Paganini

(SecurityAffairs – hacking, Emotet)

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