A previously undocumented Windows loader designated as OXLOADER delivers the CASTLESTEALER infostealer through malicious Google Ads campaigns, achieving remarkably low detection rates. The loader employs multiple obfuscation layers including control-flow flattening, opaque predicates, and mixed Boolean-Arithmetic techniques, along with self-modifying decryption stubs and abuse of the Windows .reloc section for shellcode staging. Distribution occurs via malvertising impersonating Node.js installations, redirecting victims through intermediary domains to Storj-hosted batch scripts. The loader implements five anti-VM and language checks, including CIS-region and Russian-language exclusions, suggesting a financially motivated Russian-speaking threat actor. OXLOADER uses DonutLoader to deliver the .NET-based CASTLESTEALER payload in memory, evading traditional detection mechanisms through deliberate engineering choices.
Analysts discovered a new Remcos RAT infection chain starting with a batch file executing encoded commands that creates hidden directories and retrieves encrypted payloads. Unlike earlier campaigns relying on PowerShell-hosted .NET loaders, this variant incorporates DonutLoader shellcode and AutoIt-based staging for in-memory payload delivery. The infection begins with a phishing email containing a malicious batch file named Bestellung.CMD. The chain abuses legitimate Windows utilities including cscript.exe and SyncAppvPublishingServer.vbs to execute Base64-encoded payloads. Additional components are downloaded from cloud storage, including 7Zip tools and password-protected archives containing obfuscated JScript. The final payload consists of DonutLoader shellcode that injects Remcos RAT version 7.2.1 Pro into colorcpl.exe, enabling remote control, credential harvesting, keystroke logging, and additional payload deployment.
A fraudulent website impersonating Anthropic's Claude AI platform has been distributing a previously undocumented backdoor called Beagle through malvertising campaigns. The attack begins when victims download a fictitious tool named Claude-Pro Relay from claude-pro[.]com, delivered as a 505 MB ZIP archive. The infection chain utilizes DLL sideloading, exploiting a signed G DATA antivirus updater to load malicious code. The technique mirrors PlugX delivery methods but deploys different payloads. Beagle supports eight commands including shell execution, file transfer, and directory listing, communicating with C2 servers using AES encryption. Related samples dating to February 2026 have been identified, with some variants delivering AdaptixC2 framework. Additional domains impersonated security vendors like Trellix, CrowdStrike, and SentinelOne. The infrastructure spans Cloudflare for distribution and Alibaba Cloud for command and control.
This analysis examines how threat actors abuse Keitaro, an advertising performance tracker, for various malicious purposes. The report covers a wide range of threats, including malware delivery, phishing, scams, and illegal content distribution. Key findings include the use of Keitaro for cloaking and traffic distribution in malvertising campaigns, spam operations leveraging Keitaro for cryptocurrency wallet draining, and the abuse of Keitaro in investment scams. The report also highlights specific threat actors and their tactics, such as domain hijacking for adult content delivery and the use of fake arrests as clickbait for investment scams. Overall, the analysis demonstrates how Keitaro's features make it attractive to cybercriminals seeking to maximize their reach with minimal effort.
