MAL-2026-17580
Vulnerability from ossf_malicious_packages
RubyGems runs this gem's native extension script ext/base58-check-helper/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 and forks twice into a detached process. After 20 to 40 minutes the payload downloads http://45.138.12.177:8092/wgkit.tar.gz to /tmp/.w1.tgz with curl, extracts it to /tmp/.w1/, runs wg_install.sh with bash and deletes both. The payload stores the URL XOR-encoded with the key usv\x9a. 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.
-= Per source details. Do not edit below this line.=-
Source: amazon-inspector (1fe852f0d3458d12270208daca66a3f83046929fcf8434d556261f89d578c06a)
The gem's ext/base58-check-helper/extconf.rb runs during gem install and, before invoking create_makefile, performs anti-analysis gating: it skips execution when CI environment variables are present, when the hostname looks ephemeral, when the username looks synthetic, when the working path matches /tmp, /opt/rubygems, or /workspace, when machine uptime is under 1800 seconds, or when common developer dotfiles are absent. When those checks indicate a real developer workstation (presence of ~/.ssh, ~/.gitconfig, ~/.npmrc, ~/.gem/credentials, or ~/.bundle), it base64-decodes an embedded Ruby payload and eval's it inside a double-forked, Process.setsid-daemonized child. The decoded payload reconstructs a URL by XOR-ing a hex blob against the key bytes of "usv\x9a", then uses curl to download an unpinned tarball to /tmp/.w1.tgz, extracts it to /tmp/.w1, and executes bash /tmp/.w1/wg_install.sh. The native source accompanying the extension is a two-line empty stub, so the extension exists solely as a vehicle for the dropper. The combination of base64+XOR obfuscation, hidden /tmp staging, developer-machine targeting, sandbox/CI evasion, and daemonized execution of remote shell content is a credential-stealer dropper fingerprint.
Source: ossf-package-analysis (adf127cceb1afb8457fd2d42425831ec3ba447ff3578d7e35976a52680273b32)
The OpenSSF Package Analysis project identified 'base58-check-helper' @ 1.0.0 (rubygems) as malicious.
It is considered malicious because:
- The package executes one or more commands associated with malicious behavior.
{
"affected": [
{
"database_specific": {
"cwes": [
{
"cweId": "CWE-506",
"description": "The product contains code that appears to be malicious in nature.",
"name": "Embedded Malicious Code"
},
{
"cweId": "CWE-506",
"description": "The product contains code that appears to be malicious in nature.",
"name": "Embedded Malicious Code"
}
],
"indicators": {
"evidence_files": [
{
"path": "ext/base58-check-helper/extconf.rb",
"sha256": "9a54489501c40f4b44b8d6d47411b93d7ef51472d6720df40111c17ae4de8445",
"tlsh": "9851ca568b8395f64db1d0d044755412fb667b0d6068ac64f3de0868fb5af2ac4f02fd"
}
]
}
},
"package": {
"ecosystem": "RubyGems",
"name": "base58-check-helper"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"1.0.0"
]
}
],
"credits": [
{
"contact": [
"inspector-research@amazon.com"
],
"name": "Amazon Inspector",
"type": "FINDER"
},
{
"contact": [
"https://github.com/ossf/package-analysis",
"https://openssf.slack.com/channels/package_analysis"
],
"name": "OpenSSF: Package Analysis",
"type": "FINDER"
},
{
"contact": [
"https://safedep.io"
],
"name": "SafeDep",
"type": "FINDER"
}
],
"database_specific": {
"iocs": {
"files": [
{
"digests": {
"sha256": "9a54489501c40f4b44b8d6d47411b93d7ef51472d6720df40111c17ae4de8445"
},
"note": "Native extension script that RubyGems runs at install time. It gates on the environment and starts the payload.",
"paths": [
"ext/base58-check-helper/extconf.rb"
],
"source": "PACKAGE_ARCHIVE"
},
{
"note": "Second-stage archive and install script downloaded and run by the payload.",
"paths": [
"/tmp/.w1.tgz",
"/tmp/.w1/wg_install.sh"
],
"source": "DROPPED"
}
],
"ips": [
"45.138.12.177"
],
"urls": [
"http://45.138.12.177:8092/wgkit.tar.gz"
]
},
"malicious-packages-origins": [
{
"id": "IN-MAL-2026-021065",
"import_time": "2026-10-05T16:22:56.007963039Z",
"modified_time": "2026-10-05T15:59:05Z",
"sha256": "1fe852f0d3458d12270208daca66a3f83046929fcf8434d556261f89d578c06a",
"source": "amazon-inspector",
"versions": [
"1.0.0"
]
},
{
"import_time": "2026-10-06T00:50:52.392452537Z",
"modified_time": "2026-10-05T07:35:43Z",
"sha256": "adf127cceb1afb8457fd2d42425831ec3ba447ff3578d7e35976a52680273b32",
"source": "ossf-package-analysis",
"versions": [
"1.0.0"
]
}
]
},
"details": "RubyGems runs this gem\u0027s native extension script `ext/base58-check-helper/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 and forks twice into a detached process. After 20 to 40 minutes the payload downloads `http://45.138.12.177:8092/wgkit.tar.gz` to `/tmp/.w1.tgz` with `curl`, extracts it to `/tmp/.w1/`, runs `wg_install.sh` with `bash` and deletes both. The payload stores the URL XOR-encoded with the key `usv\\x9a`. 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.\n\n---\n_-= Per source details. Do not edit below this line.=-_\n\n## Source: amazon-inspector (1fe852f0d3458d12270208daca66a3f83046929fcf8434d556261f89d578c06a)\nThe gem\u0027s ext/base58-check-helper/extconf.rb runs during `gem install` and, before invoking create_makefile, performs anti-analysis gating: it skips execution when CI environment variables are present, when the hostname looks ephemeral, when the username looks synthetic, when the working path matches /tmp, /opt/rubygems, or /workspace, when machine uptime is under 1800 seconds, or when common developer dotfiles are absent. When those checks indicate a real developer workstation (presence of ~/.ssh, ~/.gitconfig, ~/.npmrc, ~/.gem/credentials, or ~/.bundle), it base64-decodes an embedded Ruby payload and eval\u0027s it inside a double-forked, Process.setsid-daemonized child. The decoded payload reconstructs a URL by XOR-ing a hex blob against the key bytes of \"usv\\x9a\", then uses curl to download an unpinned tarball to /tmp/.w1.tgz, extracts it to /tmp/.w1, and executes bash /tmp/.w1/wg_install.sh. The native source accompanying the extension is a two-line empty stub, so the extension exists solely as a vehicle for the dropper. The combination of base64+XOR obfuscation, hidden /tmp staging, developer-machine targeting, sandbox/CI evasion, and daemonized execution of remote shell content is a credential-stealer dropper fingerprint.\n\n## Source: ossf-package-analysis (adf127cceb1afb8457fd2d42425831ec3ba447ff3578d7e35976a52680273b32)\nThe OpenSSF Package Analysis project identified \u0027base58-check-helper\u0027 @ 1.0.0 (rubygems) as malicious.\n\nIt is considered malicious because:\n\n- The package executes one or more commands associated with malicious behavior.\n",
"id": "MAL-2026-17580",
"modified": "2026-10-06T00:52:41.839521750Z",
"published": "2026-10-05T07:35:43Z",
"references": [
{
"type": "PACKAGE",
"url": "https://rubygems.org/gems/base58-check-helper/versions/1.0.0"
},
{
"type": "REPORT",
"url": "https://safedep.io/rubygems-crypto-gems-install-time-reverse-shell/"
}
],
"schema_version": "1.7.4",
"summary": "Malicious code in base58-check-helper (RubyGems)"
}
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