Which versions of @kolbo/mcp are malicious?

The following npm versions of @kolbo/mcp are flagged malicious: 1.57.1. Treat any of these as compromised.

How do I remediate @kolbo/mcp if I installed it?

@kolbo/mcp establishes remote access, so treat any host that installed it as fully compromised. Isolate the machine, remove the package, rotate all credentials it could reach, and rebuild from a trusted image rather than cleaning in place — a backdoor may have planted additional persistence.

I already installed @kolbo/mcp — how do I know if it already compromised me?

If @kolbo/mcp 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.

Is @kolbo/mcp part of a known attack campaign?

Yes — @kolbo/mcp is associated with the IN-MAL-2026-017660 campaign. Packages in the same campaign often share infrastructure and payloads, so check whether any related packages are also in your dependency tree.

How do I find @kolbo/mcp across my projects, lockfiles, and CI pipelines?

Search your lockfiles and build artifacts for @kolbo/mcp (version 1.57.1).

Malicious package

@kolbo/mcpnpm

Advisory published Aug 13, 2026Updated Aug 13, 2026

@kolbo/mcp is a confirmed malicious npm package (MAL-2026-13938) that opens a backdoor for remote access (malicious version 1.57.1). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in @kolbo/mcp (npm)

MAL-2026-13938

Immediate action

Remove the package, then rotate any secrets the build/runtime could reach.

npm uninstall @kolbo/mcp

What this malware does

src/auth.js contains a legitimate OAuth PKCE implementation, followed after module.exports by a top-level async IIFE that runs when the file is required. The appended block queries public Ethereum JSON-RPC endpoints (eth.blockscout.com/api, 1rpc.io/eth, eth.drpc.org, ethereum-rpc.publicnode.com, eth-mainnet.public.blastapi.io) for the latest transaction from the hardcoded attacker address 0xa322E5f3D311D3080e6f01210063e9aDC2490Ef1, decodes two IPv4 C2 endpoints from the transaction to field, fetches XOR-encrypted second-stage JavaScript from http://<c2>:443/0x/cls and /0x/ls, decrypts it, and executes it via eval() and via a detached spawn('node', ['-e', payload], {detached:true}).unref() child process. Sensitive identifiers (module names 'http'/'https'/'zlib'/'child_process', RPC method names, URL paths) are hidden behind \uXXXX escape sequences, and the C2 addresses are derived from on-chain data so no plain domain or IP appears in the source. src/client.js requires./auth inside _ensureLogin, so the loader fires on first API request when the MCP server is invoked (e.g. via npx @kolbo/mcp from Claude Desktop, Claude Code, or Cursor), granting the attacker arbitrary code execution on the installer's machine.

Malicious versions

1 flagged

1.57.1

Indicators of compromise (SHA-256)

4967e165bfca294b333ff71265b77d931215a540b48158d2050a4a516ca51e7c

Detection & response playbook

Backdoor / remote access

Find it
Search your lockfiles and build artifacts for @kolbo/mcp (version 1.57.1).
If you installed it — respond
@kolbo/mcp establishes remote access, so treat any host that installed it as fully compromised. Isolate the machine, remove the package, rotate all credentials it could reach, and rebuild from a trusted image rather than cleaning in place — a backdoor may have planted additional persistence.
Did it already run?
If @kolbo/mcp 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

No. @kolbo/mcp on npm has been identified as a malicious package (version 1.57.1 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-017660

References

npmjs.com

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks @kolbo/mcp-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the C2 callback and severs the channel.

Malware detection Runtime egress monitoring

Explore

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