Which versions of libhmac are malicious?

The following PyPI versions of libhmac are flagged malicious: 0.3.0, 0.8.28.0, 0.8.28.1, 1.1.0. Treat any of these as compromised.

How do I remediate libhmac if I installed it?

libhmac is built to steal secrets, so assume every credential the build or runtime could read is compromised. Remove it from your project and lockfile, then rotate ALL exposed secrets — npm/registry tokens, cloud keys, CI/CD secrets, SSH keys, and any .env values — from a known-clean machine. Audit logs for unauthorized use of those credentials.

I already installed libhmac — how do I know if it already compromised me?

If libhmac was installed, its post-install payload may already have run. Removing the package does not undo that — check outbound connections and credential use from the install window onward.

Is libhmac part of a known attack campaign?

Yes — libhmac is associated with the 2026-05-libhmac, IN-MAL-2026-003522 campaign. Packages in the same campaign often share infrastructure and payloads, so check whether any related packages are also in your dependency tree.

How do I find libhmac across my projects, lockfiles, and CI pipelines?

Search your lockfiles and build artifacts for libhmac (4 malicious versions).

Malicious package

libhmacPyPI

Advisory published May 20, 2026Updated May 26, 2026

libhmac is a confirmed malicious PyPI package (MAL-2026-4194) that steals credentials and exfiltrates sensitive data (malicious versions 0.3.0, 0.8.28.0, 0.8.28.1…). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in libhmac (PyPI)

MAL-2026-4194

Immediate action

Remove the package, then rotate any secrets the build/runtime could reach.

pip uninstall libhmac

What this malware does

The PyPI name 'libhmac' matches the well-known libyal/libhmac C forensics library (HMAC primitive), but the package contents have nothing to do with HMAC primitives. The shipped code is a complete Chromium-family browser-extension hijacking toolkit. ChromeManager.ReplaceInPlaceExtensions (src/libhmac/extension_patcher.py) enumerates all Chrome/Edge/Brave/Vivaldi profiles for the current user, copies attacker payload bytes (dm_core_bg.js, dm_core_bg.wasm) into each extension's version directory, rewrites manifest.json to add <all_urls> host permissions and a relaxed content_security_policy (wasm-unsafe-eval, broad connect-src), strips extensions.ui.developer_mode_encrypted_hash from Chrome's Secure Preferences (src/libhmac/preferences_handler.py:84), and recomputes Chrome's super_mac using the per-browser HMAC seed extracted from resources.pak (src/libhmac/hmac_calculator.py:223) to defeat tamper detection. The advertised purpose in pyproject.toml is 'Chromium extension host sync, CSP relaxation, and in-place extension patching'. Author metadata is a placeholder ('libhmac maintainers', no email, no homepage, no repo) under a 'Proprietary' license. A developer who runs pip install libhmac expecting the libyal HMAC library instead pulls in a browser-compromise toolkit; downstream packages can import libhmac to weaponize any installer's browser profiles. The combination of name impersonation of an established OSS library, anonymous maintainer identity, and offensive capability with no legitimate dual-use framing is the fingerprint of namespace-abuse malware infrastructure.

The package is a loader of an infostealer that modifies browser extensions to intercept credentials and cryptowallet data. The installation is not automatic, the code is intended to be triggered externally, but includes hardcoded exfiltration target.

Category: MALICIOUS - The campaign has clearly malicious intent, like infostealers.

Campaign: 2026-05-libhmac

Reasons (based on the campaign):

crypto-related
exfiltration-credentials
exfiltration-crypto
exfiltration-browser-data

Malicious versions

4 flagged

0.3.00.8.28.00.8.28.11.1.0

Indicators of compromise (SHA-256)

9bb9951f337f12dd13b75c0646ac2c38680ea60f2ad841b9f102e441993c9c56

fccbd481dd2bd04274c5045995a08ddbcf302780c24f39eb63821d5d63a998d1

Detection & response playbook

Credential / info stealer

Find it
Search your lockfiles and build artifacts for libhmac (4 malicious versions).
If you installed it — respond
libhmac is built to steal secrets, so assume every credential the build or runtime could read is compromised. Remove it from your project and lockfile, then rotate ALL exposed secrets — npm/registry tokens, cloud keys, CI/CD secrets, SSH keys, and any .env values — from a known-clean machine. Audit logs for unauthorized use of those credentials.
Did it already run?
If libhmac was installed, its post-install payload may already have run. Removing the package does not undo that — check outbound connections and credential use from the install window onward.

Frequently asked questions

No. libhmac on PyPI has been identified as a malicious package (versions 0.3.0, 0.8.28.0, 0.8.28.1, 1.1.0 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

2026-05-libhmacIN-MAL-2026-003522

References

Credits

Amazon Inspector · finder
Kamil Mańkowski (kam193) · reporter

Detect & block this

O3 blocks libhmac-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the credential exfiltration and severs the channel.

Malware detection Runtime egress monitoring

Explore

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