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"Emotet" Banking Malware Steals Data Via Network Sniffing

A new banking malware spotted by Trend Micro intercepts and logs outgoing traffic in an effort to harvest sensitive information from victims.

Dubbed “Emotet” by the security company, the Trojan doesn't use phishing or form field insertion like other financial malware. Instead, it relies on network sniffing because this technique makes its malicious activities more difficult to detect.

The threat is distributed by cybercriminals with the aid of spam emails apparently related to money transfers or shipping invoices. The bogus notifications contain links that point to websites set up to serve the malware to victims.

After infecting a computer, Emotet downloads a configuration file containing information on the targeted financial organizations. The files analyzed by Trend Micro contained a list of banks from Germany, this being the most affected country. Data from the company's Smart Protection Network indicates that while most infections are in the EMEA region, there are victims in the APAC region and North America as well.

Another component file downloaded by Emotet on infected systems is a DLL file that's responsible for intercepting and stealing outgoing network traffic. The component injects itself into all processes, including Web browsers in order to compare accessed websites against the list of organizations contained in the configuration file. When a match is found, the entire content of the website, including the data entered by the victim on it, is intercepted and saved.

Researchers have noted that the banking Trojan is also capable of intercepting data sent over secure connections by hooking APIs such as PR_OpenTcpSocket, PR_Write, PR_Close, PR_GetNameForIndentity, Closesocket, Connect, Send and WsaSend to monitor network traffic.

The stolen data is encrypted and placed in a registry entry, while component files are placed in separate registry entries, Trend Micro said.

"The decision to storing files and data in registry entries could be seen as a method of evasion. Regular users often do not check registry entries for possibly malicious or suspicious activity, compared to checking for new or unusual files. It can also serve as a countermeasure against file-based AV detection for that same reason," Joie Salvio, Threat Response Engineer at Trend Micro, noted in a blog post on Friday.

Trend Micro is currently trying to determine how the data stolen by Emotet is sent back to the attackers.

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Eduard Kovacs (@EduardKovacs) is a contributing editor at SecurityWeek. He worked as a high school IT teacher for two years before starting a career in journalism as Softpedia’s security news reporter. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.