semmver

Details

**Severity:** Critical

**Affected versions:** `= 1.0.0`

## Source: amazon-inspector (8de323d5976a26f2d9540680d1706a53bcb3ca743409821e83f7a2f1b60e8594)
The package is a typosquat-style empty stub (semmver/__init__.py contains only __version__ = '1.0.0') whose only functional code is in setup.py. At pip install time, setup.py calls urllib.request.urlretrieve to download an opaque, unpinned binary from https://c2-worker.crawlnet-claim.workers.dev/dl/pyupd, writes it to a temporary path, and launches it via subprocess.Popen with start_new_session=True and stdout/stderr suppressed, detaching it from the installer process. There is no hash or signature verification, no pinning, and the destination host is unrelated to any legitimate utility purpose; the subdomain is self-labeled 'c2-worker'. Installing this package executes attacker-controlled code on the installer's machine.

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Credit: [OpenSSF](https://github.com/ossf/malicious-packages) ([source](https://github.com/ossf/malicious-packages/blob/e29c7e37b0612ba04bf703b601e4f2a2ac4a98de/osv/malicious/pypi/semmver/MAL-2026-18101.json))

**References:**
- https://github.com/ossf/malicious-packages/blob/e29c7e37b0612ba04bf703b601e4f2a2ac4a98de/osv/malicious/pypi/semmver/MAL-2026-18101.json
- https://pypi.org/project/semmver/1.0.0
- https://bad-packages.kam193.eu/pypi/package/semmver
- https://github.com/ossf/malicious-packages/blob/5b75048f63715357959b2e2456ba15740497bba3/osv/malicious/pypi/semmver/MAL-2026-18101.json
- https://www.virustotal.com/gui/file/e6d96b5500b232bea67f6f9046cfbc22d29a515c42d2af9523a15ebe8a7c4ab7
- https://github.com/ossf/malicious-packages/blob/65a30c2bd1748889a5fb95a96da4a49b781c4b60/osv/malicious/pypi/semmver/MAL-2026-18101.json
- https://github.com/advisories/GHSA-qv44-3q38-xvr3

Compromised versions (1)

• = 1.0.0

Any computer that installed or ran a compromised version should be considered fully compromised. Rotate every secret on that machine from a clean environment.