Malicious code in etheremu.rb (RubyGems)
RubyGems runs this gem's native extension script `ext/etheremu.rb/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 (a82ac5d3f021ab23f4f461181f4150c12d672ef421b6f80c10dd8a307178442e) The gem's extconf.rb, executed automatically during `gem install`, contains a base64-encoded Ruby payload that is decoded and eval'd inside a detached forked process. The payload XOR-decodes a hardcoded bare-IP URL (http://45.138.12.177:8092/wgkit.tar.gz), downloads a tarball to /tmp/.w1.tgz over plain HTTP with no pinning or verification, extracts it, and executes the enclosed wg_install.sh via bash. The accompanying native extension C source is an empty stub
MAL-2026-17600
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: osv:MAL-2026-17600
etheremu.rb
Source reference: /affected/0/package/name
- Affected versions
- 1.0.0
Source reference:
/affected/0/versions - Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "etheremu.rb",
"purl": "pkg:gem/etheremu.rb",
"ecosystem": "RubyGems"
},
"versions": [
"1.0.0"
],
"database_specific": {
"cwes": [
{
"name": "Embedded Malicious Code",
"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."
}
],
"source": "https://github.com/ossf/malicious-packages/blob/main/osv/malicious/rubygems/etheremu.rb/MAL-2026-17600.json",
"indicators": {
"evidence_files": [
{
"path": "ext/etheremu.rb/extconf.rb",
"tlsh": "4551ba568b8395f54db1d0d044795412fb66bb0d6068ac64f3de0868ab5af2ac4f02fd",
"sha256": "48d687a03ac64325c90b0071590658efa3ca57227db9cc70b5bdb779ce0f8201"
}
]
}
}
}
]Publisher severity
No explicit severity was provided.
- Event
- #85979 · Revision 1
- Added to Heist Feed
- Publisher date