A malware loader linked to a TrickBot-associated intrusion crew was observed fetching an encoded payload from GitHub files disguised as images, decoding the data into shellcode, and launching a 64-bit Cobalt Strike beacon directly in memory. The sample used obfuscated strings, manually resolved APIs from ntdll.dll and kernel32.dll, and loaded wininet.dll to handle network communications, reflecting a stealth-focused delivery chain commonly associated with post-compromise ransomware activity.
Analysis of the beacon configuration tied command-and-control traffic to rainbowmango.info subdomains over HTTPS/443, with gpupdate.exe configured as the spawn-to process for execution. One GitHub account previously used to host the payload was later deleted, indicating likely operational cleanup by the actor as defenders and researchers tracked the infrastructure and tooling behind the campaign.

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Walmart Global Tech published an analysis of a new malware loader attributed to an actor involved in TrickBot Cobalt Strike and ransomware operations. The loader downloaded encoded payload data from GitHub-hosted files masquerading as images and ultimately launched a 64-bit Cobalt Strike beacon in memory.
The analysis noted that a GitHub account previously used to host the payload, Asderfolkij092, had been deleted by the time of review. Researchers assessed this as possible operational cleanup by the threat actor after campaign use.
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