Which versions of aiosendletter are malicious?

The following PyPI versions of aiosendletter are flagged malicious: 0.2.0, 3.7, 3.8, 3.9, 4.0, 4.1, 4.3, 4.5, 4.6. Treat any of these as compromised.

How do I remediate aiosendletter if I installed it?

aiosendletter 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 aiosendletter — how do I know if it already compromised me?

If aiosendletter was ever installed, its post-install/runtime payload may have already executed. O3's L7 egress monitoring and runtime eBPF sensors detect the credential exfiltration or command-and-control callback after install and block the malicious outbound channel, so you catch and contain the actual compromise — not just the presence of the package.

Is aiosendletter part of a known attack campaign?

Yes — aiosendletter is associated with the 2026-09-aiosendletter, IN-MAL-2026-020143, IN-MAL-2026-020142 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 aiosendletter across my projects, lockfiles, and CI pipelines?

Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for aiosendletter (9 malicious versions). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging aiosendletter across your stack and pipelines.

Malicious package

aiosendletterPyPI

aiosendletter is a confirmed malicious PyPI package (MAL-2026-16264) that steals credentials and exfiltrates sensitive data (malicious versions 0.2.0, 3.7, 3.8…). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in aiosendletter (PyPI)

MAL-2026-16264

Immediate action

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

pip uninstall aiosendletter

What this malware does

The package ships a module (e.py) that prompts for administrator elevation via UAC, archives the contents of %LOCALAPPDATA%\logs with shutil.make_archive, and POSTs the resulting zip to a hardcoded attacker-controlled endpoint at https://sparkling-pine-f202.stilluer-sweden.workers.dev/ using requests.post. The %LOCALAPPDATA%\logs tree commonly contains Discord, browser, and game-tool artifacts including session data. The package's PyPI summary ("Safe bug reporter for sending local logs via Cloudflare Workers") and identifiers such as aiosendletter_logs are cover-story framing for bulk exfiltration of installer-owned data. Separately, pyproject.toml declares the Python stdlib name "ctypes" as an unpinned PyPI runtime dependency, causing pip to resolve and install whatever package currently occupies that registry name and execute its lifecycle code on the installer's machine — a dependency-confusion install-time code path in addition to the primary stealer payload.

Package hides code to exfiltrate files. Most releases target unclear files, but some reveal the goal to exfiltrate sensitive Telegram data.

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

Campaign: 2026-09-aiosendletter

Reasons (based on the campaign):

files-exfiltration
target:telegram

Malicious versions

9 flagged

0.2.03.73.83.94.04.14.34.54.6

Indicators of compromise (SHA-256)

4e81e3b63bbe719f6d0bdd42930bb2f3235b8e41cbacf449743bb7dca67c9f08

26f8a892e736700361508bf143cc8a5eeeb0c929ee01301b9bf336fbdeb90f90

46b706e618e75dd4f864a55a33a06cfa98c890d310735b1dea71ad86fe299fe6

Detection & response playbook

Credential / info stealer

Find it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for aiosendletter (9 malicious versions). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging aiosendletter across your stack and pipelines.
If you installed it — respond
aiosendletter 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 aiosendletter was ever installed, its post-install/runtime payload may have already executed. O3's L7 egress monitoring and runtime eBPF sensors detect the credential exfiltration or command-and-control callback after install and block the malicious outbound channel, so you catch and contain the actual compromise — not just the presence of the package.
How O3 protects you
O3 blocks aiosendletter before install through its supply-chain scanner, and if it has already run, detects and severs the exfiltration or C2 callback at runtime through L7 egress monitoring and eBPF.

Frequently asked questions

No. aiosendletter on PyPI has been identified as a malicious package (versions 0.2.0, 3.7, 3.8, 3.9, 4.0, 4.1, 4.3, 4.5, and 1 more flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

2026-09-aiosendletterIN-MAL-2026-020143IN-MAL-2026-020142

References

Credits

Amazon Inspector · finder
Kamil Mańkowski (kam193) · reporter

Detect & block this

O3 blocks aiosendletter-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

All malware advisories How O3 detects malware Vulnerability database