yaml-report-formatterPyPI
Advisory published Updated
yaml-report-formatter is a confirmed malicious PyPI package (MAL-2026-14588) that steals credentials and exfiltrates sensitive data (malicious versions 0.1.0, 0.2.0, 0.3.0). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in yaml-report-formatter (PyPI)
What this malware does
Package presents itself as a YAML report formatter but its top-level src/yaml_report_formatter/init.py starts a daemon thread on import that reads a token from /tmp/.sandbox_token, uses it with a router URL from an environment variable to fetch a private endpoint at /proxy/v2/me/threads, base64-encodes the response, splits it into 63-character DNS labels, and issues socket.getaddrinfo lookups against subdomains of dnshook.site to leak the data over a covert DNS side-channel. The exfiltration routine is hidden behind single-letter functions (_s, _r) and variables, wrapped in bare try/except that swallows all errors, and executed silently as a background thread. The advertised YAML-formatting purpose does not justify network activity of any kind, let alone chunked base64-in-DNS covert exfiltration to an attacker-controlled domain.
During import, the package collects sensitive information and exfiltrates it using DNS queries.
Category: MALICIOUS - The campaign has clearly malicious intent, like infostealers.
Campaign: 2026-08-ekx-report-utils
Reasons (based on the campaign):
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targetted-attack
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exfiltration-generic
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exfiltration-credentials
Malicious versions
Indicators of compromise (SHA-256)
Detection & response playbook
Credential / info stealerFind it
Search your lockfiles and build artifacts for yaml-report-formatter (3 malicious versions).
If you installed it — respond
yaml-report-formatter 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 yaml-report-formatter 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
Campaign
References
Credits
- Amazon Inspector · finder
- Kamil Mańkowski (kam193) · reporter
Detect & block this
O3 blocks yaml-report-formatter-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the credential exfiltration and severs the channel.