Dark Reading is part of the Informa Tech Division of Informa PLC

This site is operated by a business or businesses owned by Informa PLC and all copyright resides with them.Informa PLC's registered office is 5 Howick Place, London SW1P 1WG. Registered in England and Wales. Number 8860726.

Attacks/Breaches

10/31/2018
03:30 PM
Connect Directly
Google+
Twitter
RSS
E-Mail
50%
50%

Pervasive Emotet Botnet Now Steals Emails

Researchers discover new cyber-spying function in the persistent malware operation's arsenal.

After a month of laying low, the ubiquitous Emotet botnet has come alive again with a new module that siphons email messages from machines infected by the malware.

Hundreds of thousands of victim machines across 170 countries are now likely outfitted with the email-stealing component of the malware, according to research by Kryptos Logic. The US is by far the biggest victim to date, with somewhere between 40,000 and 50,000 infected machines.

The email-stealing module represents a dramatic shift for the malware, adding a cyber espionage and reconnaissance element to it. "We haven't observed this aggressive [behavior] in nonstate [hackers before]," says Salim Neino, CEO of Kryptos Logic. "They were a bit quiet for the month, and then they came out with this new email mass exfiltration [module]."  

Emotet has been high on the radar screen of the US Department of Homeland Security's US-CERT, which this summer posted a detailed alert on how to detect and defend against the malware, a sophisticated Trojan that has evolved significantly in its four years of life. Emotet has been used to drop ransomware on water utilities and other high-profile organizations. In addition, it is one of the most expensive malware threats to hit state and local governments, with costs of up to $1 million per incident.

The botnet has been evolving into more of an attack-for-hire service since this summer. It typically spreads via rigged email attachments and infected URLs. Once it executes on a machine, it spreads via the EternalBlue vulnerability that acts as a worm, spreading via hacked Windows domain credentials and then spreading widely throughout an infected organization.

Emotet's new email-stealing function could be a value add of sorts for other hacker groups who want to hire the botnet service, Neino notes, or it could indicate that Emotet has teamed with a more aggressive hacking group.

Symantec calls the cybercrime group behind Emotet "Mealybug." "Most recently, Mealybug appears to have expanded its operations to primarily become a distributor of threats for other attack groups," Symantec said in July blog post about the botnet. "It appears to have changed its business model in recent times, evolving from targeting banking customers in Europe to using its infrastructure to act as a global packing and delivery service for other threat actors."

Emotet, which previously stole email contacts from victims via an Outlook Messaging API module, employs the built-in Windows MAPI function. It can grab emails in an inbox as far back as 180 days, according to Kryptos' discovery. "It's basically moving from semi-personalized attacks in spam ... to more personalized and maintainable attacks," Neino says.

It works like this: The email-stealing module scans the emails of a victim and saves the results in a temporary file, which ultimately gets transmitted to the botnet command-and-control server if it's larger than 116 bytes. If it's smaller, the Windows dynamic link library (DLL) module reads the file, according to Kryptos. The company posted a blog today with the technical details.

The best defense against Emotet is strong endpoint security and threat intelligence, Neino says, including his firm's free TellTale service, where organizations can type in their IP address to see whether they are infected with Emotet or other botnet malware, including WannaCry.

In addition to the usual patching and layered security, email certification measures, and other typical practices, restricting inbound SMB traffic is another defense against Emotet, according to US-CERT.

"Emotet is one of the most active – and now most aggressive – groups out there maintaining a foothold in distributing malware," Neino says.

Related Content:

Black Hat Europe returns to London Dec 3-6 2018  with hands-on technical Trainings, cutting-edge Briefings, Arsenal open-source tool demonstrations, top-tier security solutions and service providers in the Business Hall. Click for information on the conference and to register.

Kelly Jackson Higgins is the Executive Editor of Dark Reading. She is an award-winning veteran technology and business journalist with more than two decades of experience in reporting and editing for various publications, including Network Computing, Secure Enterprise ... View Full Bio

Comment  | 
Print  | 
More Insights
Comments
Newest First  |  Oldest First  |  Threaded View
I 'Hacked' My Accounts Using My Mobile Number: Here's What I Learned
Nicole Sette, Director in the Cyber Risk practice of Kroll, a division of Duff & Phelps,  11/19/2019
6 Top Nontechnical Degrees for Cybersecurity
Curtis Franklin Jr., Senior Editor at Dark Reading,  11/21/2019
Anatomy of a BEC Scam
Kelly Jackson Higgins, Executive Editor at Dark Reading,  11/21/2019
Register for Dark Reading Newsletters
White Papers
Video
Cartoon Contest
Current Issue
Navigating the Deluge of Security Data
In this Tech Digest, Dark Reading shares the experiences of some top security practitioners as they navigate volumes of security data. We examine some examples of how enterprises can cull this data to find the clues they need.
Flash Poll
Rethinking Enterprise Data Defense
Rethinking Enterprise Data Defense
Frustrated with recurring intrusions and breaches, cybersecurity professionals are questioning some of the industrys conventional wisdom. Heres a look at what theyre thinking about.
Twitter Feed
Dark Reading - Bug Report
Bug Report
Enterprise Vulnerabilities
From DHS/US-CERT's National Vulnerability Database
CVE-2019-11287
PUBLISHED: 2019-11-23
Pivotal RabbitMQ, versions 3.7.x prior to 3.7.21 and 3.8.x prior to 3.8.1, and RabbitMQ for Pivotal Platform, 1.16.x versions prior to 1.16.7 and 1.17.x versions prior to 1.17.4, contain a web management plugin that is vulnerable to a denial of service attack. The "X-Reason" HTTP Header ca...
CVE-2019-11291
PUBLISHED: 2019-11-22
Pivotal RabbitMQ, 3.7 versions prior to v3.7.20 and 3.8 version prior to v3.8.1, and RabbitMQ for PCF, 1.16.x versions prior to 1.16.7 and 1.17.x versions prior to 1.17.4, contain two endpoints, federation and shovel, which do not properly sanitize user input. A remote authenticated malicious user w...
CVE-2019-15593
PUBLISHED: 2019-11-22
GitLab 12.2.3 contains a security vulnerability that allows a user to affect the availability of the service through a Denial of Service attack in Issue Comments.
CVE-2019-16285
PUBLISHED: 2019-11-22
If a local user has been configured and logged in, an unauthenticated attacker with physical access may be able to extract sensitive information onto a local drive.
CVE-2019-16286
PUBLISHED: 2019-11-22
An attacker may be able to bypass the OS application filter meant to restrict applications that can be executed by changing browser preferences to launch a separate process that in turn can execute arbitrary commands.