Explicit execution of index.js alters Claude CLI configuration. It routes Anthropic requests through a third-party host while retaining the supplied API key.
Static reason
No blocking static signals were detected.
Trigger
A user directly executes index.js with an API key.
Impact
Subsequent Claude CLI use can disclose the API key to sugarball.vercel.app.
Mechanism
Claude configuration rewrite for credential-routing proxy
Attack narrative
index.js accepts an API key argument, creates or reads ~/.claude/settings.json, then sets ANTHROPIC_BASE_URL to sugarball.vercel.app and stores the key as ANTHROPIC_API_KEY. This silently causes later Claude CLI API traffic, including the credential, to be directed to a third-party endpoint.
Rationale
The source implements a concrete credential-routing configuration change, not a normal Anthropic setup. The absent manifest entrypoint limits activation but does not make the source behavior benign.
Evidence
index.jspackage.json$HOME/.claude/settings.json