Fileless Execution

LevelBlue GSOC has identified accelerating ValleyRAT campaigns delivered through fake installers and malicious emails targeting Chinese and Japanese-speaking users. The email-based attack chain uses DLL sideloading via a legitimate VLC executable to load a malicious DLL that downloads an RC4-encrypted, Donut-generated ValleyRAT payload, which is then injected into a suspended rundll32.exe process for fileless execution. The malware incorporates extensive anti-analysis checks (memory size, sleep timing, CPU count, VHD boot detection) and establishes persistence via registry Run keys.

2026-05-266 minANY.RUNhigh

In May 2026, ANY.RUN observed a surge in sophisticated phishing and malware campaigns utilizing fileless execution, browser-based credential theft, and legitimate workflow abuse. Key threats included Agent Tesla credential harvesting, ClickFix fileless malware, BlobPhish in-memory page generation, and phishing-to-RMM chains bypassing traditional MFA via real-time OTP interception.

2026-05-196 minTrend Microhigh

Trend Micro MDR analyzed Banana RAT, a sophisticated banking trojan operated by SHADOW-WATER-063 targeting Brazilian financial institutions. The malware utilizes a server-side polymorphic build pipeline to deliver unique, AES-encrypted PowerShell payloads that execute filelessly in memory. Once active, it enables operator-driven fraud through remote input control, keylogging, deceptive banking overlays, and a specialized Pix QR code interception subsystem.

2026-05-137 minTrend Microcritical

Quasar Linux (QLNX) is an advanced, previously undocumented Linux Remote Access Trojan (RAT) designed to compromise developer workstations and facilitate supply chain attacks. It employs sophisticated evasion techniques, including fileless execution, process name spoofing, and dynamically compiled LD_PRELOAD and eBPF rootkits, alongside a PAM backdoor to harvest critical cloud and repository credentials.

2026-05-137 minMicrosofthigh

Microsoft Threat Intelligence identified a macOS-focused campaign by North Korean threat actor Sapphire Sleet that uses social engineering to deliver malicious AppleScripts disguised as Zoom updates. The attack leverages built-in macOS utilities like curl and osascript to bypass security controls, manipulate TCC databases, harvest credentials, and exfiltrate sensitive data such as cryptocurrency wallets.

2026-05-136 minSocketcritical

The official Telnyx Python SDK on PyPI was compromised by the threat actor TeamPCP, who published malicious versions (4.87.1 and 4.87.2) containing credential-harvesting malware. The malware executes upon module import, utilizing audio steganography to deliver OS-specific payloads: a fileless in-memory harvester for Linux/macOS and a persistent binary for Windows, with exfiltrated data secured via hybrid encryption.

2026-05-136 minTrend Microcritical

The Russia-aligned APT group Pawn Storm has launched a sophisticated campaign deploying the PRISMEX malware suite against Ukrainian and NATO defense supply chains. The attack chain leverages two critical vulnerabilities, CVE-2026-21509 and CVE-2026-21513, to achieve zero-click execution, utilizing advanced steganography and COM hijacking to evade detection while communicating via legitimate cloud services.

2026-05-137 minTrend Microhigh

A targeted campaign is delivering the PureLog Stealer via localized copyright violation lures. The attack employs a sophisticated multi-stage infection chain, utilizing a Python-based loader to bypass AMSI, establish registry persistence, and execute the final .NET stealer entirely in memory to evade detection.

2026-05-136 minSophoshigh

Threat actors are evolving 'ClickFix' social engineering campaigns to target macOS users with the MacSync infostealer. Recent iterations bypass traditional security controls by tricking users into executing obfuscated terminal commands that deploy fileless, API-gated AppleScript payloads designed to harvest credentials, browser data, and cryptocurrency wallet seed phrases.