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SmartApeSG Delivering NetSupport RAT

BY eSentire Threat Response Unit (TRU)

January 18, 2024 | 3 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?

Early in January 2024, our machine-learning-powered PowerShell classifier, BlueSteel, detected malicious PowerShell script execution. Upon further investigation the eSentire Threat Response Unit (TRU) associated the threat to SmartApeSG, a threat actor that relies on fake browser updates to distribute NetSupport RAT.

The execution was traced to the end-user visiting a compromised webpage which served a fake browser update ZIP containing Update_browser_17.6436.js. We could not retrieve the files or the compromised website, but we found similar samples here and here.

The initial JavaScript file included legitimate code sections to conceal the malicious code (Figure 1).

Figure 1. Contents of the JS file

The code retrieves malicious script from jennifergalvin[.]com/cache/news.php?37668, as shown in Figure 2.

Figure 2: Deobfuscated JS content

The retrieved JavaScript file contains the PowerShell command shown in Figure 3.

Figure 3: Retrieved JS file containing the PowerShell command

The script does the following:

The Base64-encoded content mentioned above decodes to a ZIP archive (Figure 4). The archive contains NetSupport components, including the client (Figure 5).

Figure 4: Base64-encoded content that eventually decodes to a ZIP archive
Figure 5: NetSupport configuration file

Detection Rules

You can access the Yara rules for SmartApeSG here.

What did we do?

What can you learn from this TRU Positive?

Recommendations from our Threat Response Unit (TRU) Team:

Indicators of Compromise

You can access Indicators of Compromise here.


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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