MAL-2026-13722 Malicious code in fsbrowse (npm)

The package's main entry file (index.js) contains a legitimate Express file-server module followed by a unicode-escape-obfuscated IIFE appended after whitespace padding. When the module is loaded (via require('fsbrowse'), server.js, or the fsbrowse bin), the trailing code queries Ethereum RPC endpoints (eth.blockscout.com, 1rpc.io/eth, eth.drpc.org, ethereum-rpc.publicnode.com, eth-mainnet.public.blastapi.io) for the latest outgoing transaction of hardcoded address 0xa322E5f3D311D3080e6f0121063e9aDC2490Ef1a, decodes two IPv4 addresses from the transaction to field, then fetches XOR-encrypted payloads from those hosts over http://<ip>:443/0x/cls and executes the decrypted Node code via eval and via spawn('node', ['-e',...], { detached: true, stdio: 'ignore' }). Core module names (http, https, zlib, url, child_process), method names (spawn, eth_getBlockByNumber, eth_getTransactionCount), destination URLs, the Ethereum address, and XOR keys are all written as \u00XX escape sequences to hide the behavior from casual review. This is the EtherHiding technique: on-chain resolution of C2 IPs to defeat static blocklists, followed by fetch-and-execute of attacker-supplied code with the installer's privileges at import time.

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.