IntroductionIn May 2026, Zscaler ThreatLabz identified a new malware family that we track as MLTBackdoor that is likely leveraged by a ransomware-related threat actor. MLTBackdoor has been observed by ThreatLabz being delivered in a multi-stage ClickFix infection chain. MTLBackdoor supports a set of commands like downloading and uploading files from the ... Read More

IntroductionThere was a significant increase in software supply chain attacks in March 2026. There were five major software supply-chain attacks that occurred including the Axios NPM package compromise, which has been attributed to a North Korean threat actor. In addition, a hacking group known as TeamPCP was able to compromise ... Read More

Introduction Xloader is an information stealing malware family that evolved from Formbook and targets web browsers, email clients, and File Transfer Protocol (FTP) applications. Additionally, Xloader may execute arbitrary commands and download second-stage payloads on an infected system. The author of Xloader continues to update the codebase, with the most recent ... Read More

IntroductionThreat actors often take advantage of major global events to fuel interest in their malicious activities. Zscaler ThreatLabz is diligently tracking a surge in cybercriminal activity that capitalizes on the elevated political climate in the Middle East. This increased malicious activity includes discoveries that are directly tied to the ongoing ... Read More

IntroductionGuLoader (also known as CloudEye) is a highly obfuscated malware family that was first observed in December 2019. It serves primarily as a downloader for Remote Access Trojans (RATs) and information stealers, which are delivered to compromised systems. The threat actors that distribute GuLoader often host malware on legitimate platforms ... Read More

IntroductionMatanbuchus is a malicious downloader, written in C++, which has been offered as a Malware-as-a-Service (MaaS) since 2020. Over this time, Matanbuchus has undergone several development stages. In July 2025, version 3.0 of Matanbuchus was identified in-the-wild. Matanbuchus offers threat actors the option to deploy additional payloads and perform hands-on ... Read More

IntroductionIn May 2025, Zscaler ThreatLabz discovered CVE-2025-50165, a critical remote code execution (RCE) vulnerability with a CVSS score of 9.8 that impacts the Windows Graphics Component. The vulnerability lies within windowscodecs.dll, and any application that uses this library as a dependency is vulnerable to compromise, such as a Microsoft Office document. For ... Read More

IntroductionZscaler ThreatLabz has identified a new malware family that we named YiBackdoor, which was first observed in June 2025. The malware is particularly interesting because it contains significant code overlaps with IcedID and Latrodectus. Similar to Zloader and Qakbot, IcedID was originally designed for facilitating banking and wire fraud. However, IcedID has since ... Read More

IntroductionZloader (a.k.a. Terdot, DELoader, or Silent Night) is a Zeus-based modular trojan that emerged in 2015. Zloader was originally designed to facilitate banking, but has since been repurposed for initial access, providing an entry point into corporate environments for the deployment of ransomware. Following an almost two-year hiatus, Zloader reemerged in ... Read More

IntroductionActive since 2011, SmokeLoader (aka Smoke or Dofoil) is a popular malware loader that is designed to deliver second-stage payloads such as trojans, ransomware, and information stealers. Over the years, SmokeLoader has been updated and enhanced to evade detection and optimize payload delivery. SmokeLoader’s capabilities have also been expanded through a modular ... Read More