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UNC5518 Access-as-a-Service Campaign via ClickFix and Fake CAPTCHA Pages

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Last updated
3 unique sources, 5 articles

Summary

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The FileFix social engineering attack, a variant of the ClickFix family, impersonates Meta account suspension warnings to trick users into installing the StealC infostealer malware. The campaign has evolved over two weeks with different payloads, domains, and lures, indicating an attacker testing and adapting their infrastructure. The FileFix technique, created by red team researcher mr. d0x, uses the address bar in File Explorer to execute malicious commands. The campaign employs steganography to hide a second-stage PowerShell script and encrypted executables inside a JPG image, which is believed to be AI-generated. The StealC malware targets credentials from various applications, cryptocurrency wallets, and cloud services, and can take screenshots of the active desktop. The FileFix attack uses a multilingual phishing site to trick users into executing a malicious command via the File Explorer address bar. The attack leverages Bitbucket to host the malicious components, abusing a legitimate source code hosting platform to bypass detection. The attack involves a multi-stage PowerShell script that downloads an image, decodes it into the next-stage payload, and runs a Go-based loader to launch StealC. The attack uses advanced obfuscation techniques, including junk code and fragmentation, to hinder analysis efforts. The FileFix attack is more likely to be detected by security products due to the payload being executed by the web browser used by the victim. The FileFix attack demonstrates significant investment in tradecraft, with carefully engineered phishing infrastructure, payload delivery, and supporting elements to maximize evasion and impact. The MetaStealer attack, a variant of the ClickFix family, uses a fake Cloudflare Turnstile lure and an MSI package disguised as a PDF to deploy the MetaStealer infostealer malware. The attack involves a multi-stage infection chain that includes a DLL sideloading technique using a legitimate SentinelOne executable. The MetaStealer attack targets crypto wallets and other sensitive information, using a combination of social engineering and technical evasion techniques to deploy malware. Previously, threat actors tracked as UNC5518 leveraged a social engineering tactic called ClickFix to deploy the CORNFLAKE.V3 backdoor. The campaign used fake CAPTCHA pages to trick users into executing malicious PowerShell scripts, providing initial access to systems. This access was then monetized by other threat groups, including UNC5774 and UNC4108, which deployed additional payloads. The attack began with users interacting with compromised search results or malicious ads, leading them to fake CAPTCHA pages. Users were then tricked into running a malicious PowerShell command, which downloaded and executed the CORNFLAKE.V3 backdoor. This backdoor supported various payload types and could collect system information, which was transmitted via Cloudflare tunnels to evade detection. CORNFLAKE.V3 is an updated version of CORNFLAKE.V2, featuring host persistence and additional payload support. The campaign also involved the deployment of WINDYTWIST.SEA, a backdoor that supports lateral movement within infected networks.

Timeline

  1. 17.09.2025 17:01 1 articles · 12d ago

    MetaStealer attack uses fake Cloudflare Turnstile and MSI package

    The MetaStealer attack, a variant of the ClickFix family, uses a fake Cloudflare Turnstile lure and an MSI package disguised as a PDF to deploy the MetaStealer infostealer malware. The attack involves a multi-stage infection chain that includes a DLL sideloading technique using a legitimate SentinelOne executable. The MetaStealer attack targets crypto wallets and other sensitive information, using a combination of social engineering and technical evasion techniques to deploy malware.

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  2. 16.09.2025 15:00 4 articles · 13d ago

    FileFix attack impersonates Meta and deploys StealC infostealer

    The FileFix attack has been observed using a combination of fake support portals, Cloudflare CAPTCHA error pages, and clipboard hijacking to socially engineer victims into running malicious PowerShell code. The attack also involves the use of an AutoHotkey (AHK) script to profile the compromised host and deliver additional payloads, including AnyDesk, TeamViewer, information stealers, and clipper malware. The attack has also been observed using an MSHTA command pointing to a lookalike Google domain to retrieve and execute a remote malicious script.

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  3. 21.08.2025 19:25 2 articles · 1mo ago

    UNC5518 Access-as-a-Service Campaign via ClickFix and Fake CAPTCHA Pages

    The ClickFix attack family has evolved to include new variants that use fake Cloudflare Turnstile lures and MSI packages disguised as PDFs to deploy malware. These attacks involve multi-stage infection chains that include DLL sideloading techniques and advanced evasion methods. The MetaStealer attack, a variant of ClickFix, targets crypto wallets and other sensitive information using a combination of social engineering and technical evasion techniques.

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