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StealthBait: Evasive Phishing Tactics

BY eSentire Threat Response Unit (TRU)

October 17, 2023 | 5 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?

In early September 2023, we received notifications of a phishing campaign targeting the finance industry, with approximately 300 users affected.

The phishing email contained an HTML file. When this file is opened, it communicates with the attacker’s server, which then prompts the user to input their credentials into a fake Microsoft login page.

Depending on the user’s location, the attacker’s server will either display a fake loading page or a deceptive “404 Not Found” error page. 

Figure 1: Fake Microsoft login page

The entered credentials would be posted to an attacker’s C2 server (in our sample, it’s h40pbqrb5ra.lopapscop[.]ws).

Looking at the source code of the HTML file, we noticed that the script is using the CryptoJS library to decrypt the encrypted data using the AES algorithm in CBC mode with PKCS#7 padding, as shown below, where the value “WPfkidgH” would contain the hardcoded email address.

Figure 2: Obfuscated code

Upon decrypting the code, we see that most of the content is in a hexadecimal format.

Further decoding, we can see the series of strings under the variable var _0xe53b. We can map the strings to specific variables within the deobfuscated code, and we will get a clear understanding of the code’s functionality, as shown below.

Figure 3: Snippet of the deobfuscated and mapped strings

Looking at the code, we can see that it implements various anti-analysis / evasion techniques, such as:

For “Displaying the loading screen or “404 Not Found” error anti-analysis / evasion technique, the code gathers the data of the machine via the API request to https://pro.ip-api[.]com/json/?key=pD3jjrEbn4o2CQ1 and then sends the data in a JSON format to the server (for example, enwpcfr7me.lopapscop[.]ws/obufsssssssscaaatoion/ or .wtis4sz9mjF/jdjdmxnx[.]online/obufsssssssscaaatoion/) as shown in Figure 4.

Figure 4: Data being sent to the server

The ‘NAMEOFTHEGUY’ (Figure 4) contains likely the threat actor’s handle for the phishing campaign, in our case it’s “Waaaa.004.aavy”.

Upon the returned data from POST request, the function checks a returned property named "Allow_Online" that is received from the server. Based on its value, it takes different actions:

Additionally, if the current location's hostname is "localhost" or "", a message "Don't run me here!" is logged to the console.

Figure 5: Image of the "loadingScreen"

Upon further investigation of the domains, we discovered more than a thousand associated phishing pages on URLScan.

Figure 6: Related phishing landing pages

What did we do?

What can you learn from this TRU positive?

Recommendations from our Threat Response Unit (TRU) Team:

Indicators of Compromise







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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