@decoopus/claude-setupnpm
Advisory published Updated
@decoopus/claude-setup is a confirmed malicious npm package (MAL-2026-18054) that runs destructive / sabotage code (malicious versions 1.0.0, 1.0.2, 1.0.13). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in @decoopus/claude-setup (npm)
What this malware does
The CLI prompts the user for an Anthropic API key (sk-ant-...) and writes it, together with a hardcoded gateway base URL https://api-anthropic.help, into Claude Desktop's configuration in every location it can reach: Windows registry policies at HKCU\SOFTWARE\Policies\Claude via reg.exe, macOS managed preferences for com.anthropic.claudefordesktop via defaults write, claude_desktop_config.json, and all profile JSON files under configLibrary. The domain api-anthropic.help is a lookalike of api.anthropic.com and is not operated by Anthropic, so after setup every Claude Desktop request — including the user's API key and all prompt/response traffic — is transparently relayed to an attacker-controlled endpoint. The package also kills running Claude.exe/Claude processes and recursively deletes Session Storage, Local Storage, IndexedDB, cookies, and host-creds/custom3p/probe-cache files across standard, Claude-3p, and Windows Store MSIX install locations, then relaunches Claude Desktop so the next authentication flow is forced through the attacker gateway. A comment references a prior gateway host api.vokes.in that the package explicitly overwrites, and the shipped DEFAULT_MODELS list contains fabricated model names (claude-fable-5-1, claude-opus-5-5, claude-sonnet-5-5, claude-haiku-5-5) under a 'Claude Max 20x · API Usage Billing' label that do not correspond to Anthropic's product lineup, consistent with an iterated phishing/relay operation.
Any computer that has this package installed or running should be considered fully compromised. All secrets and keys stored on that computer should be rotated immediately from a different computer. The package should be removed, but as full control of the computer may have been given to an outside entity, there is no guarantee that removing the package will remove all malicious software resulting from installing it.
Malicious versions
Indicators of compromise (SHA-256)
Detection & response playbook
Destructive / sabotageFind it
Search your lockfiles and build artifacts for @decoopus/claude-setup (3 malicious versions).
If you installed it — respond
@decoopus/claude-setup carries a destructive/sabotage payload. Remove it immediately, restore any affected data from clean backups, and verify integrity of build outputs that may have been tampered with.
Did it already run?
If @decoopus/claude-setup 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
Detect & block this
O3 blocks @decoopus/claude-setup-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the malicious outbound activity and severs the channel.