Colin Mc Hugo

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Colin Mc Hugo
Security Engineer Manager & CEO at Quantum Infinite Solutions Group Ltd.

Masslogger Trojan Upgraded to Steal All Your Outlook, Chrome Credentials

February 19, 2021

A credential stealer notorious for focusing on Home windows programs has resurfaced in a brand new phishing marketing campaign that goals to steal credentials from Microsoft Outlook, Google Chrome, and on the spot messenger apps.

Primarily directed towards customers in Turkey, Latvia, and Italy beginning mid-January, the assaults contain the usage of MassLogger — a .NET-based malware with capabilities to hinder static evaluation — constructing on comparable campaigns undertaken by the identical actor towards customers in Bulgaria, Lithuania, Hungary, Estonia, Romania, and Spain in September, October, and November 2020.

MassLogger was first noticed within the wild final April, however the presence of a brand new variant implies malware authors are continuously retooling their arsenal to evade detection and monetize them.

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“Though operations of the Masslogger trojan have been beforehand documented, we discovered the brand new marketing campaign notable for utilizing the compiled HTML file format to start out the an infection chain,” researchers with Cisco Talos said on Wednesday.


Compiled HTML (or .CHM) is a proprietary on-line assist format developed by Microsoft that is used to offer topic-based reference info.

The brand new wave of assaults commences with phishing messages containing “legitimate-looking” topic strains that seem to narrate to a enterprise.

One of many emails focused at Turkish customers had the topic “Home buyer inquiry,” with the physique of the message referencing an hooked up quote. In September, October and November, the emails took the type of a “memorandum of understanding,” urging the recipient to signal the doc.


Whatever the message theme, the attachments adhere to the identical format: a RAR multi-volume filename extension (e.g., “70727_YK90054_Teknik_Cizimler.R09”) in a bid to bypass makes an attempt to dam RAR attachments utilizing its default filename extension “.RAR.”

These attachments include a single compiled HTML file that, when opened, shows the message “Customer support,” however actually comes embedded with obfuscated JavaScript code to create an HTML web page, which in flip incorporates a PowerShell downloader to connect with a respectable server and fetch the loader in the end answerable for launching the MassLogger payload.

Except for exfiltrating the amassed knowledge by way of SMTP, FTP or HTTP, the most recent model of MassLogger (model 3.0.7563.31381) options performance to pilfer credentials from Pidgin messenger consumer, Discord, NordVPN, Outlook, Thunderbird, Firefox, QQ Browser, and Chromium-based browsers akin to Chrome, Edge, Opera, and Courageous.

“Masslogger could be configured as a keylogger, however on this case, the actor has disabled this performance,” the researchers famous, including the risk actor put in a model of Masslogger management panel on the exfiltration server.

With the marketing campaign nearly totally executed and current solely in reminiscence with the only real exception of the compiled HTML assist file, the importance of conducting common reminiscence scans can’t be overstated sufficient.

“Customers are suggested to configure their programs for logging PowerShell occasions akin to module loading and executed script blocks as they are going to present executed code in its deobfuscated format,” the researchers concluded.

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