MAL-2026-10135 Malicious code in theta-sdk-js (npm)

[email protected] ships src/decrypt.js and src/providers/BaseProvider.js which together implement a hidden execution channel. On module load, decrypt.js reads two encrypted blobs (rsa.db, des.db) from node_modules/tchain-api/apps/docs/app/, DES-decrypts them using the hardcoded password 'hydra' via crypto-js, and returns the plaintext. Top-level IIFEs in src/providers/BaseProvider.js spawn detached node child processes (spawn('node', [], { detached: true, stdio: ['pipe','ignore','ignore'] })), pipe the decrypted plaintext into stdin for execution, and call unref() so the child outlives the parent. The runtime dependency tchain-api@^1.2.5 — declared in package.json — supplies the encrypted payload files, so npm install theta-sdk-js automatically stages the payload host. The distributed dist/thetajs.cjs.js (declared as main) is clean and does not contain this code; the dropper lives only in the src/ tree that is also shipped in the tarball, so consumers that import subpaths or use bundlers/tree-shakers that resolve src/index.js trigger the execution. Encrypting the payload in a sibling package with a hardcoded key, splitting the malicious code away from the declared entrypoint, and executing decoded plaintext in a detached child process are hallmarks of deliberate evasion, not legitimate SDK behavior.

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.