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Protecting End Users Against the Gootloader Malware Threat Using the Gootloader Operator’s Own Tactics

BY eSentire Threat Response Unit (TRU)

April 27, 2023 | 4 MINS READ



Threat Intelligence

Threat Response Unit

TRU Positive/Bulletin

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eSentire’s Threat Response Unit (TRU), led by researchers Joe Stewart and Keegan Keplinger, have launched a multi-pronged offensive against a growing cyberthreat: the Gootloader Initial Access-as-a-Service Operation. The Gootloader Operation is an expansive cybercrime business, and it has been active since 2018.

For the past 15 months, the Gootloader Operator has been launching ongoing attacks targeting legal professionals, working for both law firms and corporate legal departments, in the U.S., Canada, the U.K. and Australia. Between January and March 2023, TRU shut down Gootloader attacks against 12 different organizations, seven of which were law firms.

By using Search Engine Optimization (SEO) poisoning to lure unsuspecting victims to an enormous array of compromised WordPress blogs, Gootloader tailors its victim pool to a subset of organizations most likely to pay a handsome ransom. Currently, one of these “victim pools” is legal professionals working for law firms and corporate legal departments.

Gootloader infects legal employees by luring them to blogs, which are populated with content pertaining to “legal agreements” and “contracts”. When the employee visits the blog, which includes a link to what appears to be a sample “legal agreement” or “contract”, and they download the file, they are downloading Gootloader.

While Gootloader might not be a household name like many ransomware threats, the Gootloader Operation is compromising organizations across the globe and selling this access to ransomware threat actors and other cybercriminals. Since Gootloader is a “Gateway to Hands-on Intrusions”, not just annoying, automated adware, hackers use it to get a foothold in an organization’s IT environment and then spread laterally through the organization’s network to seed out ransomware or to exfiltrate data.

The Gootloader Operation is targeting law firms and law professionals because that's where they can find the most sensitive data that most people want to be kept confidential. It is the kind of data that can damage reputations, compromise business deals, expose protected witnesses, and undermine an organization’s legal case. The Cybersecurity and Infrastructure Security Agency (CISA) named it a top malware strain of 2021.

One of the most interesting aspects of Stewart and Keplinger’s research was that they were able to use the Gootloader page data to confirm the connection that other security researchers had previously reported: that the Gootloader Operator(s) had been providing Initial Access victims to the notorious Russian-speaking REvil (aka: Sodinokibi) Gang. Not only were Stewart and Keplinger able to confirm this connection, but they were also able to narrow down the timelines of all the REvil-sponsored Gootloader campaigns to the day.

Stewart and Keplinger set out to figure out a way of shutting down the growing Gootloader infections, and it turned out that the Gootloader malware operator, himself, has provided part of the answer. The Operator implemented a feature to keep his victims from being discovered by security researchers and incident responders.

Stewart and Keplinger discovered that they and other security defenders can use this same tactic to hide end-users from the Gootloader Operator, thus proactively protecting organizations from being infected.

Stewart also built a crawler for finding all the live Gootloader webpages, and eSentire is providing technical details needed to identify these pages with search engine vendors with the goal of blocking these malicious pages, thus preventing end-users from ever seeing them.

This is another way eSentire is proactively trying to protect corporate end-users from being infected with Gootloader. eSentire is sharing their methods at the RSA Security Conference in San Francisco the week of April 24th and are encouraging other security defenders to follow their lead.

In our new TRU threat research report, Gootloader Unloaded: Researchers Launch Multi-Pronged Offensive Against Gootloader, Cutting Off Traffic to Thousands of Gootloader Web Pages and Using the Operator’s Very Own Tactics to Protect End-Users, we're sharing this method as well as Gootloader threat indicators with the cybersecurity community at large and are encouraging other security defenders to follow.

Read the full report for key takeaways on:

eSentire’s Threat Response Unit (TRU) is a world-class team of threat researchers who develop new detections enriched by original threat intelligence and leverage new machine learning models that correlate multi-signal data and automate rapid response to advanced threats.

If you are not currently engaged with an MDR provider, eSentire MDR can help you reclaim the advantage and put your business ahead of disruption.

Learn what it means to have an elite team of Threat Hunters and Researchers that works for you. Connect with an eSentire Security Specialist.

eSentire Unit
eSentire Threat Response Unit (TRU)

The eSentire Threat Response Unit (TRU) is an industry-leading threat research team committed to helping your organization become more resilient. TRU is an elite team of threat hunters and researchers that supports our 24/7 Security Operations Centers (SOCs), builds threat detection models across the eSentire XDR Cloud Platform, and works as an extension of your security team to continuously improve our Managed Detection and Response service. By providing complete visibility across your attack surface and performing global threat sweeps and proactive hypothesis-driven threat hunts augmented by original threat research, we are laser-focused on defending your organization against known and unknown threats.

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