The GemStuffer campaign leverages the RubyGems package registry as an unconventional data exfiltration channel. Threat actors deploy Ruby scripts that scrape UK local government portals, package the harvested data into valid .gem archives, and push them to RubyGems using hardcoded API keys. The malware demonstrates defense evasion by overriding the HOME environment variable to a /tmp directory to isolate its credential environment, or by bypassing the gem CLI entirely to perform direct API POST requests.
ModernGov
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GemStuffer Campaign Abuses RubyGems as Exfiltration Channel Targeting UK Local Government