GCVE-110-OSM-2026-10391

npm/bs58-33 is a typosquat of the popular bs58 base58 codec (cryptocoinjs). The package contains no malicious code of its own: its src/cjs/index.cjs simply does require("base65-33x") and re-exports it. Its sole purpose is to pull in the malicious sink package base65-33x as a runtime dependency (declared dependency: base65-33x: ^5.0.1). base65-33x is a near-verbatim clone of base-x whose decode() exfiltrates every string passed to it by POSTing the raw input to a hardcoded bare-IP C2 (http://168.231.81.80:3002/api/log) before throwing; because base-x/bs58 are how crypto tooling base58-decodes private keys and seeds, the exfiltrated values are frequently secrets. The sink is reported separately as MAL-2026-13749. bs58-33 and its sibling wrappers (bs58-15, bs58-77) were published alongside the three base65 sinks by a single npm maintainer account (smallmantis) within a ~90-minute window on 2026-08-11, forming a matched six-package delivery-plus-exfiltration campaign. Installing bs58-33 is sufficient to introduce the key-exfiltration behavior into a dependent project. Judge assessment: This is a typosquat delivery wrapper whose attacker model is dependency-based key theft: the package name mimics the legitimate bs58 codec, but its entrypoint `src/cjs/index.cjs` imports `base65-33x` instead of implementing base58 itself. The publisher metadata is highly incriminating as well: `smallmantis` is a 2-day-old burner account, has a 0.6 malicious ratio, and already published three confirmed malicious sibling packages (`base65-15x`, `base65-33x`, `base65-77x`). The observed IOC `16UjcYNBG9GTK4uq2f7yYEbuifqCzoLMGS` is a Bitcoin address classified as exfil, which fits the campaign’s goal of harvesting cryptocurrency-related secrets from downstream projects. The OSV advisory’s description is consistent with the code path here, which serves only to pull in the malicious sink package as a runtime dependency and therefore enables the exfiltration campaign. ENTRY src/cjs/index.cjs (main: src/cjs/index.cjs) DESTINATION - 1 exfil (bitcoinAddresses) (values recorded in verified_iocs) ADDITIONAL FINDINGS - Publisher Has Other Malicious Packages - Very New NPM Publisher Account - Publisher Shows Burner-Account Pattern