Skip to main content

Malicious code in contoso-login-sim-loader (npm)

0
Unknown
Published: 09/30/2026 (09/30/2026, 04:40:31 UTC)
Source: GCVE Database
Product: contoso-login-sim-loader

Description

--- _-= Per source details. Do not edit below this line.=-_ ## Source: amazon-inspector (062ce76699c91a883d24e3ad609bb04faa3f52cbeaecfb24c1c3bcde8b496a5c) Package ships a single ~138 KB browser script whose entire body is an RC4-encrypted base64 blob decoded at runtime by an inline RC4 routine (`_zc`) with a DJB2 helper (`_zh`) and a key reconstructed by XORing a numeric array with 1410^714. Before decryption the script performs anti-analysis guards: a devtools-size heuristic (`if(_gz>160||_gp>160)return;`) that aborts execution when developer tools are open, and a block that overwrites `console.log/info/warn/debug/error` to no-ops to suppress runtime tracing. The package name `contoso-login-sim-loader` self-describes as a 'login sim(ulator) loader' while the published description reframes it as a generic 'Client-side asset loader that renders a self-contained UI component when included via a script tag.' The tarball ships no source, no exports, no dependencies, and no documentation - only the opaque encrypted payload. Any site that follows the include-via-script-tag guidance embeds attacker-controlled JavaScript, decrypted only in end-user browsers, into its own pages; the concealed payload cannot be audited without executing it, and the name plus cover-story description are consistent with a fake-login/credential-harvest overlay served to that site's visitors.

Affected software

npmghsa
contoso-login-sim-loader
Affected versions
=1.0.1

Run on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.

Technical Details

Gcve Source
db.gcve.eu
Osv Id
MAL-2026-17322
Osv Schema Version
1.7.4
Ecosystems
["npm"]

Threat ID: 6abcdddd0df196e1a9da6f63

Added to database: 09/30/2026, 10:01:01 UTC

Last updated: 09/30/2026, 10:01:01 UTC

Views: 1

Community Reviews

0 reviews

Crowdsource mitigation strategies, share intel context, and vote on the most helpful responses. Sign in to add your voice and help keep defenders ahead.

Sort by
Loading community insights…

Want to contribute mitigation steps or threat intel context? Sign in or create an account to join the community discussion.

Actions

Please log in to the Console to use AI analysis features.

Need more coverage?

Upgrade to Pro Console for AI refresh and higher limits.

For incident response and remediation, OffSeq services can help resolve threats faster.

Latest Threats

Breach by OffSeqOFFSEQFRIENDS — 25% OFF

Check if your credentials are on the dark web

Instant breach scanning across billions of leaked records. Free tier available.

Scan now
OffSeq TrainingCredly Certified

Lead Pen Test Professional

Technical5-day eLearningPECB Accredited
View courses