Sophos Managed Detection and Response (MDR) in September 2024, the infamous Lumma Stealer malware has developed with refined PowerShell instruments and superior evasion ways, leveraging pretend CAPTCHA websites to deceive customers.
Lively since mid-2022 and supplied as Malware-as-a-Service (MaaS) by a presumed Russian developer, Lumma Stealer targets delicate knowledge resembling passwords, session tokens, cryptocurrency wallets, and private info.
What makes this newest marketing campaign significantly insidious is its use of social engineering, exploiting person belief in CAPTCHA challenges to execute malicious PowerShell instructions, typically resulting in devastating knowledge theft.
PowerShell-Pushed Payloads
Sophos MDR investigations performed by the autumn and winter of 2024-25 reveal the intricate mechanics behind Lumma Stealer’s supply.
One distinguished assault vector entails customers being redirected to seemingly respectable CAPTCHA verification pages that immediate them to stick a malicious PowerShell command into Home windows’ Run dialog field or command-line interface.
This command, typically hidden behind obfuscated JavaScript, retrieves a script from a distant server, resembling “fixedzip.oss-ap-southeast-5.aliyuncs.com,” which then downloads a zipped payload disguised as “ArtistSponsorship.exe.”
In keeping with Sophos Report, this executable drops a number of information, together with an obfuscated AutoIt script, into the person’s %temp% listing.
The script connects to command-and-control (C2) servers like “snail-r1ced.cyou” (IP 104.21.84.251 by way of Cloudflare) to exfiltrate stolen knowledge, together with Chrome login credentials and cookies, with alarming precision.
In a single noticed case, a mere 6.37MB file of delicate knowledge was efficiently transmitted earlier than the method self-terminated.
One other variant entails tricking customers into opening a supposed PDF file that’s truly a remotely hosted .lnk shortcut, triggering a deeply obfuscated PowerShell script.
This script makes use of AES encryption and dynamic API decision with instruments like CyberChef revealing a transportable executable (PE) file designed to obtain additional payloads whereas masking its intent by layers of base64 encoding and misleading file paths in %appdata%.
The complexity of those evasion methods, together with dynamic loading of malicious code by way of .NET’s System.Reflection.Meeting class and the usage of legitimate-looking IRS PDFs as decoys, underscores the stealer’s means to bypass conventional defenses.
A Rising Risk Panorama for Defenders
The adaptability of Lumma Stealer’s supply strategies poses a major problem for cybersecurity defenders.
Studies from Netskope Risk Labs estimate round 5,000 pretend CAPTCHA websites could also be energetic on this marketing campaign, amplifying the risk’s attain.
Nonetheless, the evolving tactics-combining person manipulation with technical sophistication-highlight the necessity for sturdy endpoint safety and person training.
Reversing years of ingrained belief in CAPTCHA prompts is a frightening job, but it surely’s vital as attackers proceed to take advantage of this familiarity.
As Lumma Stealer stays a pervasive risk in 2025, organizations should deploy superior behavioral evaluation and scrutinize community exercise for indicators of C2 communication or knowledge exfiltration to remain forward of this crafty infostealer.
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