MAL-2026-18299Critical▾ Abyssal⚠ Exploited in the wildMalicious code in claudeopuseni (PyPI)
▾ Abyssal zone — Critical with a public exploit or in-the-wild use
impact 52.3 · likelihood 0 · exploitation 18
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Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via OSV
Last analysed / modified upstream
-= Per source details. Do not edit below this line.=-
On import, claudeopuseni/init.py invokes _boot.check(), which issues an HTTPS GET to https://thisisafalsepositive.st/cdn/v2/claudeopuseni/manifest.json, reads field 'r' as an encrypted blob (falling back to the base64-encoded _payload.PAYLOAD bundled in _payload.py when the host is unreachable), decrypts it with a ChaCha20+HMAC routine in security.unsign keyed from sha256(b'claudeopuseni.2026.channel.v1'), and passes the plaintext to builtins.exec via an attribute name assembled from chr(101,120,101,99) to hide the sink from static scanners. _boot gates detonation on the presence of a real user profile (USERPROFILE/HOME containing Documents or Downloads) and on absence of DAS_STAGED=1 or claudeopuseni_TELEMETRY=0, and caches a timestamp to suppress re-execution within 6 hours — a sandbox/CI evasion wrapper. The embedded fallback blob guarantees execution of attacker-controlled code even when the remote host is unavailable. The resulting code runs with the importing developer's privileges on any machine that imports the package in a normal user environment. The package name resembles the Anthropic Claude product family, consistent with a typosquat lure.
During installation, obfuscated code is used to fetch code hidden in an image containing a Python application with a native extension module. This module holds an obfuscated infostealer which collects sensitive data and exfiltrates them to a C2 server retrieved from transaction history in the Polygon blockchain.
Category: MALICIOUS - The campaign has clearly malicious intent, like infostealers.
Campaign: 2026-09-donutautosellsrc
Reasons (based on the campaign):
infostealer
Downloads and executes a remote executable.
obfuscation
The package contains code to detect if it is running in a sandbox environment.
malware
native-extension
steganography
c2-in-blockchain
claudeopuseniRefer to the advisory for the patched release.