ℹ️ Update: 18th January 2026
The package has been removed from NuGet.org. This has been confirmed as a reputation hijacking attempt targeting the supply chain trust model. This news article has been updated to reflect the new events.
Yesterday (17th January 2026), unusual activity began on NuGet.org. Multiple package owners reported receiving unexpected invitations to become co-owners of a package called TestPackage.Security.Research, or to join an organisation associated with a user named “darklord”.
What Happened
The package in question was published on 17th January. It contained no functional code; there were no supported framework assets, no dependencies, and its description simply read “Test package for security research purposes.”
What caught the community’s attention was the scale of the outreach. Owners of popular NuGet packages across the .NET ecosystem received these invitations, prompting warnings to spread rapidly across social media platforms.
Mattias Karlsson posted on Bluesky:
There seems to be an ongoing supply chain attack or suspicious activity on NuGet.org, where a user called darklord is trying to gain legitimacy or something by sending thousands of become owner of their packages requests, don’t accept, report to @nuget.org
Andrew Gubskiy echoed the warning:
Attention NuGet package owners! There is highly suspicious activity. Many users are receiving invitations to become co-authors of TestPackage.Security.Research from a user named darklord, or to join an organization. Do NOT accept these invitations under any circumstances.
What This Was: Reputation Hijacking
The package has since been removed from NuGet.org, and the nature of the attack has been confirmed. In a follow-up thread, Andrew Gubskiy explained:
This was a massive ‘account legitimization’ attempt. The strategy: The user sent thousands of invites to package maintainers to become co-owners or join their organization. The goal? Reputation hijacking. If a well-known maintainer accepts, that account instantly gains ’trusted’ status in the eyes of users.
This is not a direct code exploit. It is an attack on the supply chain trust model itself. Once an account gains legitimacy through association with trusted maintainers, that reputation could be weaponised to distribute malware in the future under a veil of trust.
Your reputation as a package maintainer is not just valuable to you; it is a target for attackers.
The Golden Rule
Never accept invitations to organizations or co-ownership of packages unless you’ve discussed it beforehand through official channels. Even if the profile looks real, it might be compromised.
Do not accept invitations from strangers. Full stop. If someone wants to collaborate with you on a package, they should reach out through official channels (such as the repository’s issue tracker or discussions) first. An unsolicited NuGet invitation should be treated as suspicious until proven otherwise.
How to Secure Your NuGet Presence
Based on the community’s response to this incident, here are the essential security practices every NuGet package owner should implement:
Enable Two-Factor Authentication
- ✅ Enable 2FA on your NuGet.org account
- ✅ Enable 2FA on your GitHub account (or whichever source control you use)
Without 2FA, your account can be compromised through password breaches, phishing, or credential stuffing attacks.
Use Scoped, Time-Limited API Keys
- ✅ For CI/CD pipelines, use scoped API keys that only have the permissions they need
- ✅ Set expiration dates on API keys; rotate them regularly
- ✅ Never use account-wide API keys with unlimited scope
If an API key is compromised, limiting its scope and lifetime reduces the potential damage.
Reserve Your ID Prefix
- ✅ Reserve your package ID prefix to prove you own the namespace
Microsoft provides ID prefix reservation to both establish ownership and help prevent typosquatting. This adds a verified badge to your packages and prevents others from creating packages that could be confused with yours.
Audit Your Owners List Regularly
- ✅ Review the “Owners” list on your packages periodically
- ✅ Remove any owners who no longer need access
- ✅ Verify that all listed owners are people you know and trust
Your package is only as secure as the least secure owner account.
Use Trusted Build Sources
- ✅ Build and publish packages from trusted CI/CD environments like GitHub Actions
- ✅ Avoid building on local machines where possible
- ✅ Consider adding attestations to your packages to provide cryptographic proof of your build provenance
Ignore Unexpected Requests
- ✅ Do not accept co-ownership or organisation invitations from unknown users
- ✅ Report suspicious activity to NuGet.org using the “Report package” functionality
- ✅ If someone wants to collaborate, they should open an issue or discussion on your repository first
If You Consume NuGet Packages
This incident is a reminder that supply chain security is everyone’s responsibility.
- ✅ Pin your dependencies to known-good versions rather than floating to the latest release automatically
- ✅ Review your dependency tree periodically; tools like
dotnet list package --vulnerablecan help identify known issues - ✅ Be cautious of packages with unusual characteristics: very new packages with inflated download counts, names that look similar to popular packages but with subtle differences, or packages with no clear documentation or source repository
- ✅ Consider using Software Bills of Materials (SBOMs) to track what is in your applications
The Broader Context
This incident demonstrates a new attack vector in supply chain security: reputation hijacking. Rather than compromising code directly, attackers are targeting the trust relationships that underpin open-source ecosystems.
This comes against a backdrop of increasing supply chain attacks targeting package repositories. In recent months, NuGet has seen:
- Malicious packages using homoglyph attacks (substituting Cyrillic characters for Latin ones) to impersonate legitimate crypto libraries
- Time-delayed “logic bomb” packages designed to activate years after installation
- Typosquatting attacks targeting popular libraries
The chain is only as strong as its weakest link. As Andrew Gubskiy noted in his breakdown: your reputation is the target.
Further Reading
- Attestations: The Missing Link Between Your Code and Production Trust; our guide to implementing cryptographic attestations in your build pipeline
- The 5-Minute Investment That Could Save Your Company Millions ; our introduction to Software Bills of Materials (SBOMs)
💭 The NuGet.org team responded swiftly to remove the malicious package. If you have concerns about your account security or received one of these invitations, review your account’s ownership settings and ensure 2FA is enabled.