MAL-2026-17800 Malicious code in wallet-hd-derive (RubyGems)

The gem is published as a crypto wallet utility but ships no native source; its gemspec declares extconf.rb as an extension so that gem install auto-executes it. extconf.rb decodes a base64-encoded Ruby payload and, after checking for sandbox and analysis signals (CI env, ephemeral hostnames, generated usernames matching patterns such as uA\d+/sandbox/tester/analys/scanner, cwd under /tmp, /opt/rubygems, /workspace, low machine uptime) and confirming developer-identifying files (~/.ssh, ~/.gem/credentials, etc.), double-forks a detached process via fork + Process.setsid, sleeps for 20–40 minutes, then opens a TCP connection to 45.138.12.177:8089 and pipes /bin/sh in both directions using TCPSocket and IO.popen/IO.copy_stream. The shipped library at lib/wallet_hd_derive.rb exposes only two no-op methods (build_id='ok', healthy?=true) and the README is branded for an unrelated package (bitcoin-rpc-lite), confirming the gem exists solely as a delivery vehicle for the install-time backdoor. The destination IP, base64 encoding of the payload, sandbox-evasion gating, and delayed reverse-shell establishment give a remote operator interactive /bin/sh on any developer or CI host that installs the gem.

The OpenSSF Package Analysis project identified 'wallet-hd-derive' @ 0.9.1 (rubygems) as malicious.

It is considered malicious because:

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