express-mongo-santinpm
Advisory published Updated
express-mongo-santi is a confirmed malicious npm package (MAL-2026-12377) that typosquats a legitimate package to trick installs (malicious version 1.1.9). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in express-mongo-santi (npm)
What this malware does
The package's main file index.js is a heavily obfuscated bundle (obfuscator.io-style rotated string array with base64+RC4 decoders) whose only purpose is a remote-fetch-and-execute pipeline that fires when the module is require()'d. On load it pulls in os, fs, path, crypto, child_process, and https, assembles a hardcoded IPv4 destination from four numeric octets concatenated at runtime, issues an HTTPS GET to that host, splits the response on ':' into an IV and ciphertext, derives an AES key with crypto.scryptSync, decrypts the body with createDecipheriv, writes the plaintext to a file under os.homedir(), and spawns it via child_process with cwd set to the home directory. Module, method, and destination strings are all reconstructed at runtime through the decoders, and an uncaughtException handler suppresses errors. The package name is also a typosquat of express-mongo-sanitize. Installing or importing this package results in arbitrary attacker-controlled code executing on the installer's machine under the installer's user identity.
Malicious versions
Indicators of compromise (SHA-256)
Detection & response playbook
TyposquatFind it
Search your lockfiles and build artifacts for express-mongo-santi (version 1.1.9).
If you installed it — respond
express-mongo-santi is a typosquat — you almost certainly intended a legitimately-named package. Remove express-mongo-santi, install the correct package, and rotate any secrets exposed during the install since post-install scripts may have already run.
Did it already run?
If express-mongo-santi 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 express-mongo-santi-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.