Threat Actor Targets Japanese Users With New Ursnif Variant

Security researchers discovered an attack campaign targeting Japanese users with a new variant of Ursnif banking malware.

First observed in the beginning of 2019, Cybereason reported that the campaign begins with a phishing email that attempts to trick unsuspecting Japanese users into enabling a weaponized Microsoft Office document’s embedded macros. This results in the execution of several PowerShell commands that, in turn, download an image file. The image uses steganography to hide Bebloh, malware that ultimately pulls down Ursnif’s loader from the attacker’s command-and-control (C&C) server.

The campaign’s final payload differs from previous variants in that it:

  • Creates “last-minute persistence” the moment before an infected system shuts down and injects its core dynamic link library (DLL) into explorer.exe once the machine reboots;
  • Comes with updated modules for stealing credentials from Outlook, Mozilla Thunderbird and Internet Explorer;
  • Has a new module that enables it to steal from cryptocurrency wallets and disk encryption software; and
  • Uses yet another module to evade PhishWall, a Japanese security product.

A Busy Few Months for Ursnif

This isn’t the first time cyberattackers have targeted Japanese users with Bebloh and Ursnif. In August 2018, for instance, Trend Micro detected a campaign in which threat actors used the Cutwail botnet and abused internet query files to distribute the threats. Just two months later, Trend Micro analyzed a similar operation spreading both types of malware.

Ursnif has also been busy without Bebloh. For example, Carbon Black reported on an attack campaign on Jan. 24 in which malicious actors used macros and a PowerShell script to download the malware along with GandCrab ransomware. That same day, Cisco Talos uncovered a fileless operation involving Ursnif. Then, the following month, Bromium detected a sample of the malware hidden within an image of Mario, the popular Nintendo character.

How to Detect Banking Malware Campaigns

Security professionals can defend against campaigns that spread Ursnif and other banking malware by using ahead-of-threat detection to analyze the WHOIS information of potential phishing sites. Organizations should also make use of analytics tools such as VBA editor to inspect the macro code in suspicious Office documents.

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David Bisson

Contributing Editor

David Bisson is an infosec news junkie and security journalist. He works as Contributing Editor for Graham Cluley...