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TRU Positives: Weekly investigation summaries and recommendations from eSentire's Threat Response Unit (TRU)

UpdateAgent macOS Malware

BY eSentire Threat Response Unit (TRU)

April 6, 2022 | 4 MINS READ


Threat Intelligence

Threat Response Unit

TRU Positive/Bulletin

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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?

Summary of UpdateAgent's Initiation Shell Script

UpdateAgent collects information about the system and submits it to the C2 domain (hxxps://dgu8hufljhqqu[.]cloudfront[.]net/pkg) via HTTP POST request:

The information collected includes the active user, machine ID, operating system, and version.

Then it, retrieves a DMG file from hxxps://duh59xv2mx0nn[.]cloudfront[.]net, adds the current user to the ‘sudoers’ file and disables the password prompt:

Next, it clears extended attributes on the DMG file to bypass Gatekeeper, which is a security feature in macOS aimed at reducing the likelihood of users accidentally running malware downloaded from the internet.

Similar to the Mark-of-Web attribute in Windows, macOS applications (such as browsers) add an extended attribute known as a quarantine flag to files downloaded from the internet. UpdateAgent clears all extended attributes (including the quarantine flag) using the xattr command.

Then, it uses PlistBuddy in direct mode to add arguments to a property list file. (com.shenbfgbvgsfssfmrynamdzyetzfnd.plist) under the user’s /Library/LaunchAgents/ folder for persistence:

Lastly, the cleanup actions show as follows:

How did we find it?

What did we do?

What can you learn from this TRU positive?

Recommendations from our Threat Response Unit (TRU) Team:

Ask Yourself

  1. What level of visibility do you have across your network, endpoint, and overall environment to detect malicious behavior at scale?
  2. What level of managed endpoint support do you have in place?
  3. What level of managed endpoint support do you have in place?
  4. Are you monitoring your endpoints 24/7 and what degree of control do you have to initiate a kill switch when required?

Indicators of Compromise

Indicator Note
28C2FF8C6F78EB61361DECE949108910 Initiation Shell Script
dgu8hufljhqqu[.]cloudfront[.]net Command and Control
duh59xv2mx0nn[.]cloudfront[.]net Payload Hosting

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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