block-explorer-apiRubyGems
Advisory published Updated
block-explorer-api is a confirmed malicious RubyGems package (MAL-2026-17780) that steals credentials and exfiltrates sensitive data (malicious version 0.9.1). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in block-explorer-api (RubyGems)
What this malware does
The gem's native-extension build script (extconf.rb) decodes a base64-encoded Ruby payload and passes it to eval() inside a double-forked, detached child process with stdio redirected to /dev/null. The decoded payload opens a TCP connection to the hardcoded bare-IP C2 45.138.12.177:8089 and bridges it to /bin/sh via IO.popen and IO.copy_stream in both directions, yielding a full interactive reverse shell on the installer's host under the installing user. Execution is gated by anti-analysis checks that skip CI runners, ephemeral/sandbox hostnames (uvm, firecracker, sandbox, vagrant), generated analyst usernames (uA\d+, sandbox, tester, analys, scanner), common analysis working paths (/opt/rubygems, /tmp, /var/tmp, /workspace), and hosts with uptime under 1800 seconds, firing only when developer-signal files such as ~/.ssh, ~/.gem/credentials, ~/.gitconfig, or ~/.npmrc are present, and after a randomized 20-40 minute delay. The shipped library at lib/block_explorer_api.rb is an inert 10-line stub (VERSION, build_id, healthy?) and the gemspec name (block-explorer-api, authored by generic 'block maintainers') does not match the README, which describes the package as 'bitcoin-rpc-lite'; the install hook contains the entire functional payload while the advertised library does nothing.
The OpenSSF Package Analysis project identified 'block-explorer-api' @ 0.9.1 (rubygems) as malicious.
It is considered malicious because:
- The package executes one or more commands associated with malicious behavior.
Malicious versions
Indicators of compromise (SHA-256)
Detection & response playbook
Credential / info stealerFind it
Search your lockfiles and build artifacts for block-explorer-api (version 0.9.1).
If you installed it — respond
block-explorer-api is built to steal secrets, so assume every credential the build or runtime could read is compromised. Remove it from your project and lockfile, then rotate ALL exposed secrets — npm/registry tokens, cloud keys, CI/CD secrets, SSH keys, and any .env values — from a known-clean machine. Audit logs for unauthorized use of those credentials.
Did it already run?
If block-explorer-api was installed, its post-install payload may already have run. Removing the package does not undo that — check outbound connections and credential use from the install window onward.
Frequently asked questions
Campaign
References
Credits
- Amazon Inspector · finder
- OpenSSF: Package Analysis · finder
Detect & block this
O3 blocks block-explorer-api-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the credential exfiltration and severs the channel.