eth-address-utilsRubyGems

RubyGems runs this gem's native extension script ext/req_throttle_mini/extconf.rb during gem install. The script exits without action on CI runners and sandboxes, based on CI environment variables, the hostname, the username and the working directory. It continues if the system uptime is over 30 minutes and the home directory holds .ssh, .gitconfig, .npmrc, .gem/credentials or .bundle. It then decodes a Base64 Ruby payload, forks twice into a detached process, waits 20 to 40 minutes and opens a reverse shell that connects /bin/sh to 45.138.12.177 on TCP port 8090. The shell reconnects every 30 seconds. The Ruby code in lib/ is a decoy. The RubyGems account reqthrottle_3474 published this gem and 41 others with the same loader on 2026-10-05.

The gem advertises itself as an Ethereum address utility library but its extconf.rb (auto-executed by gem install) carries a base64-encoded payload that is decoded and passed to eval inside a double-forked, detached background process. The decoded payload sleeps 20-40 minutes and then opens a TCPSocket to the hardcoded remote host 45.138.12.177 on port 8090, bridging the socket to IO.popen(['/bin/sh'],'r+') — a reverse shell giving the operator of that IP full remote code execution on the installer's host under the installing user's privileges. The extension declares a native component named req_throttle_mini but ships no corresponding C sources; create_makefile is appended only as camouflage. Payload execution is gated by anti-analysis checks that skip CI environments, ephemeral/sandbox hostnames (uvm/firecracker/sandbox/vagrant), synthetic analyst usernames (sandbox/tester/analys/scanner), build paths under /tmp, /opt/rubygems, /workspace, systems with uptime under 1800 seconds, and hosts lacking developer-identity artifacts such as ~/.ssh, ~/.gitconfig, ~/.gem/credentials, or ~/.bundle — so only real developer workstations are compromised. The library name, the fake native-extension stub, and the sandbox evasion together confirm this is a disguised remote-access implant, not a build helper.

The OpenSSF Package Analysis project identified 'eth-address-utils' @ 1.0.0 (rubygems) as malicious.

It is considered malicious because:

• The package executes one or more commands associated with malicious behavior.