Lumma Stealer infection with Sectop RAT (ArechClient2), (Fri, Apr 17th)

Category :

SANS Full Feed

Posted On :

Introduction

This diary provides indicators from a Lumma Stealer infection that was followed by Sectop RAT (ArechClient2). I searched for cracked versions of popular copyright-protected software, and I downloaded the initial malware after following the results of one such search. This is a common distribution technique for various families of malware, and I often find Lumma Stealer this way.

In this case, the initial malware for Lumma Stealer was delivered as a password-protected 7-zip archive. The extracted malware is an inflated Windows executable (EXE) file at 806 MB. The EXE is padded with null-bytes (0x00), a technical which increases the EXE size while allowing the compressed archive file to be much smaller. The password-protected archive and inflated EXE file are designed to avoid detection.

Images from the infection


Shown above: Example of a page with instructions to download the initial malware file.


Shown above: Traffic from the infection filtered in Wireshark.


Shown above: Sectop RAT persistent on an infected Windows host.

Indicators of Compromise

Example of download link from the site advertising cracked versions of copyright-protected software:

hxxps[:]//incolorand[.]com/how-visual-patch-enhances-ui-consistency-across-releases/?utm_source={CID}&utm_term=Adobe%20Premiere%20Pro%20(2026)%20Full%20v26.0.2%20Espa%C3%B1ol%20[Mega]&utm_content={SUBID1}&utm_medium={SUBID2}

Example of URL for page with the file download instructions:

hxxps[:]//mega-nz.goldeneagletransport[.]com/Adobe_Premiere_Pro_%282026%29_Full_v26.0.2_Espa%C3%B1ol_%5BMega%5D.zip?c=ABUZ4WkRgQUA_YUCAFVTFwASAAAAAACh&s=360721

Example of URL for file download from site above site impersonating MEGA:

hxxps[:]//arch.primedatahost3[.]cfd/auth/media/JvWcFd5vUoYTrImvtWQAASTh/Adobe_Premiere_Pro_(2026)_Full_v26.0.2_Espa%C3%B1ol_%5BMega%5D.zip

Downloaded file:

Extracted malware:

  • SHA256 hash: 4849f76dafbef516df91fecfc23a72afffaf77ade51f805eae5ad552bed88923
  • File size: 806,127,604 bytes
  • File name: appFile.exe
  • File type: PE32 executable (GUI) Intel 80386, for MS Windows
  • File description: Inflated Windows EXE file for Lumma Stealer, padded with null-bytes

Deflated malware:

Lumma Stealer command and control (C2) domains from Triage sandbox analysis:

  • cankgmr[.]cyou
  • carytui[.]vu
  • decrnoj[.]club
  • genugsq[.]best
  • longmbx[.]click
  • mushxhb[.]best
  • pomflgf[.]vu
  • strikql[.]shop
  • ulmudhw[.]shop

Follow-up malware:

Example of Sectop RAT C2 traffic from an infected Windows host:

  • hxxp[:]//91.92.241[.]102:9000/wmglb
  • hxxp[:]//91.92.241[.]102:9000/wbinjget?q=66B553A8B94CE37C16F4EBC863D51FCC
  • tcp[:]//91.92.241[.]102:443/ – encoded or otherwise encrypted traffic (not HTTPS/TLS)


Bradley Duncan
brad [at] malware-traffic-analysis.net

(c) SANS Internet Storm Center. https://isc.sans.edu Creative Commons Attribution-Noncommercial 3.0 United States License.