An npm typosquat of mathjs carried a RAT that only decrypts when you pass it the right matrix.

SafeDep disclosed on September 21 that the package mathmain shipped a multi-stage loader whose decryption password is the JSON-stringified lower triangular factor of a matrix the caller supplies, so the payload stays inert and unanalysable until a victim uses the library normally. Malicious default published September 17, encrypted payload first appeared August 27. The implant uses Slack, Telegram and Base Sepolia testnet command channels, then runs a subwatcher process under Node. Download counts are unreliable because npm reported zero registry-wide downloads on September 17. (SafeDep)