Gootkit Identified Via Lead-Driven Threat Hunt

Adversaries don’t work 9-5 and neither do we. At eSentire, our 24/7 SOCs are staffed with Elite Threat Hunters and Cyber Analysts who hunt, investigate, contain and respond to threats within minutes.

We have discovered some of the most dangerous threats and nation state attacks in our space – including the Kaseya MSP breach and the more_eggs malware.

Our Security Operations Centers are supported with Threat Intelligence, Tactical Threat Response and Advanced Threat Analytics driven by our Threat Response Unit – the TRU team.

In TRU Positives, eSentire’s Threat Response Unit (TRU) provides a summary of a recent threat investigation. We outline how we responded to the confirmed threat and what recommendations we have going forward.

Here’s the latest from our TRU Team…

What did we find?

• In early August, we uncovered the Gootkit trojan impacting three separate eSentire customers.
• Gootkit is a pervasive threat delivered through drive-by social engineering attacks.
• It employs a network of compromised websites to host payloads. Compromised websites are padded with generic keywords, typically relevant to business professionals, and are used to manipulate search results.

• Victims are lured to compromised websites via poisoned search results and presented with a fake forum overlay, guiding the victim to a malicious file.

• Payloads are delivered and executed by the victim without a need for any exploit.

• Please review our security advisory to learn how threat actors poison websites globally to infect business professionals with ransomware, intrusion tools, and banking trojans.

Figure 1 Google search results containing Gootkit landing page

Figure 2 Gootkit landing page employing a fake forum overlay

How did we find it?

• eSentire’s 24/7 SOC identified Gootkit within a manufacturing customer’s environment as part of ongoing monitoring.

What did we do?

• Threat data collected from this incident was ingested as leads for additional threat hunting activities. These threat hunts identified additional Gootkit infections impacting two separate customers.
• The Threat Response Unit (TRU) conducted additional research for detection opportunities.

What can you learn from this TRU positive?

• Threat actors are increasingly relying on social engineering techniques to trick users into executing malicious code without the need for exploits.
• The Gootkit threat continues to find success in seeding web search results with their malicious content, showing resilience against attempts to identify and diminish their network of compromised landing pages. Users need to be on high alert when searching for document templates.

Recommendations from our Threat Response Unit (TRU) Team:

Social Engineering threats can be difficult to detect and stop, so it’s critical for organizations to establish a top-down security culture with strong cyber hygiene practices as the first line of defense. However, it’s worth noting that cyber hygiene alone may not be enough.

Therefore, we recommend:

1. Ensuring your downloaded content is what you intended. So, if you download a PDF template document but you are served a JavaScript file, do not open it. Prior to opening any file, you can right-click on the file icon and go to Properties to see what kind of file it is.
2. Making sure you trust document sources. Even legitimate Word and Excel documents from the Internet can lead to loader malware.
3. Using Windows Attack Surface Reduction rules to block JavaScript and VBscript from launching downloaded content. Read more: Microsoft Docs.
4. Employing an Endpoint Detection and Response (EDR) product​.
5. Mandating security awareness training for all company employees as part of the onboarding process and consistently throughout their tenure at the company. The training should focus on the following topics:
   1. The downloading and execution of files from unverified sources​
   2. Process of reporting potential security incidents​
   3. Educate users about safe Internet browsing habits​
   4. Avoid free versions of paid software​
   5. Inspect the full URL before downloading files to ensure it matches the source (e.g., Microsoft Teams should come from a Microsoft domain)​
   6. Always inspect the extension of files, do not trust the filetype logo alone. An executable file can be disguised as a PDF or office document​
   7. Employees need to report security threats without fear of repercussion, even if caused accidentally​

Ask Yourself…

• Threats continue to innovate and find success in their social engineering attacks. Do you have the capability to rapidly identify and contain malicious code executed unwittingly by users in your environment?

If you’re not currently engaged with a Managed Detection and Response provider, we highly recommend you partner with us for security services in order to disrupt threats before they impact your business.

Want to learn more? Connect with an eSentire Security Specialist.