SleeperGem: Three Booby-Trapped Ruby Packages Slip Onto RubyGems
Researchers say the malicious gems sat quietly on the official Ruby package registry, waiting to pull down further attacker code onto developer laptops.
Key points
- Researchers have named a new supply chain attack SleeperGem, targeting developers who use the Ruby programming language.
- Three malicious packages were uploaded to RubyGems, the official public library where Ruby developers download code.
- One package, git_credential_manager, was published on July 18, 2026 across four versions (2.8.0 through 2.8.3).
- A second package, Dendreo, appeared in versions 1.1.3 and 1.1.4.
- The packages were designed to fetch further attacker code onto the machines of developers who installed them.
Security researchers have flagged a fresh attempt to poison the software supply chain, this time aimed at people who build applications using Ruby, a popular programming language.
The campaign has been named SleeperGem. It uses three booby-trapped packages that were uploaded to RubyGems, the official public library where Ruby developers grab ready-made bits of code to plug into their own projects.
When a developer installs one of these packages, the code inside quietly reaches out to a server controlled by the attackers and pulls down more malicious software. That second stage is where the real damage happens.
Think of it as a Trojan horse left on a shelf that thousands of builders trust.
Which packages were involved?
The rogue uploads, first reported by The Hacker News, are:
git_credential_manager, published on July 18, 2026, in versions 2.8.0, 2.8.1, 2.8.2 and 2.8.3.Dendreo, published in versions 1.1.3 and 1.1.4.
Both names are designed to look legitimate. git_credential_manager mimics a well-known tool that stores login details for Git, the system developers use to manage their code. Dendreo borrows the name of a real French training-software company, a classic trick to make a bad package look like the real thing.
Why does this matter to non-developers?
Supply chain attacks like this one do not target you directly. They target the people who build the apps, websites and internal tools that you and your employer rely on.
If a developer at a bank, a hospital or a retailer installs a poisoned package, the attacker can end up with access to that developer's machine. From there they can steal source code, login tokens, or plant more malicious code inside products that eventually reach customers.
That is why researchers treat these incidents seriously even when the download counts look small.
What should developers and their employers do?
Anyone whose team uses Ruby should immediately check whether git_credential_manager or Dendreo has been installed in the versions listed above. If so, remove them, rotate any credentials that were stored on the affected machine, and review recent activity on Git repositories the developer had access to.
RubyGems typically pulls confirmed malicious packages once they are reported, but the window between upload and takedown is exactly when victims get caught.
The broader lesson is old but still ignored. Package registries like RubyGems, npm and PyPI operate on trust. Anyone can publish. Names can be spoofed. Versions can be swapped. A single careless install command can pull attacker code straight into a corporate laptop.
Organisations that build software should be treating third-party packages the way they treat email attachments from strangers: verify before you open.
Researchers are still analysing the second-stage payload the SleeperGem packages fetch, and the full list of affected users is not yet public. Expect more detail as the investigation continues.
