Targeted open source malware attacks on developers soar

Sonatype has published research showing a sharp rise in targeted open source malware attacks on developers. Malicious package advisories increased from 21 incidents in 2023 to 1,576 in 2025.

The findings point to a shift in software supply chain attacks away from broad campaigns and toward packages designed to influence what developers choose to install. Attackers are increasingly trying to compromise developer environments before code reaches production.

According to the research, nearly half of all classified open source malware now imitates trusted software or developer tools. The share reached 47.3%, up from an annual average of 14% between 2021 and 2024.

That trend coincides with a broader increase in malware aimed directly at developers. The report found a 3.6-fold rise in developer-targeting malware between 2023 and 2025.

Another finding concerns when malicious code executes. Sonatype said 53% of malicious packages were designed to compromise developer environments during installation, while its report on AI-era malicious packages found 62% executed at that stage.

Such attacks can give adversaries access to credentials and tokens before many standard security checks take effect. The report argues that this marks a shift from older approaches based on typosquatting or exploiting vulnerabilities after deployment.

Attack methods

The data also showed a rise in concealment techniques. Sonatype found 36% of malicious advisories now contain at least one stealth technique, while one in four malicious packages use methods such as obfuscation and multi-stage droppers.

These methods can make malicious software harder to inspect and block. They also increase the burden on software teams that must quickly decide whether a package is safe to adopt.

The change in attacker behaviour comes as developers make greater use of AI coding assistants and automated tools to discover and select software dependencies. That has altered how software is evaluated and introduced into projects, creating new opportunities for attackers to present harmful packages as legitimate options.

Sonatype Research Labs was founded in 2011 and has focused on software supply chain intelligence for more than a decade. The group has tracked malware campaigns and shifts in open source risk as software development has become more dependent on third-party components.

The latest report was released as the research unit marked its 15-year anniversary. Sonatype said the work reflects a growing need to distinguish between vulnerabilities in open source components and software that is intentionally malicious.

Adam Cazzolla, Head of Research Labs, outlined that shift in emphasis.

"The AI era forced us to rethink where software supply chain research was headed. Vulnerabilities remain important, but we realized the next frontier is understanding intentionally malicious software and the attackers behind it. That's exactly what Attacking the Assembly Line explores: not just how attacks are changing, but why they're changing," said Adam Cazzolla, Head of Research Labs, Sonatype.

The report presents the change as one of strategy rather than scale alone. Instead of spreading large volumes of simple malware in the hope of catching victims, attackers are putting more effort into carefully designed packages that appear credible to a defined audience of developers or organisations.

This matters because modern software projects often depend on a large number of external packages. If attackers can influence early decisions about which components to install, they can gain access much earlier in the development process.

Industry shift

Brian Fox, Co-founder and CTO, linked the findings to the wider role of open source software in business systems.

"Fifteen years ago, people questioned whether open source vulnerabilities even mattered. Many organizations didn't realize how much open source they were actually shipping. Software supply chain attacks and software composition analysis were not a part of the conversation. Today, every organization depends on software they didn't write, and attackers know it. The challenge is no longer discovering that software supply chains matter. It's giving developers intelligence they can trust as AI changes how software gets built," said Brian Fox, Co-founder and CTO.

Sonatype is known in the software supply chain market as the steward of Maven Central and the developer of Nexus Repository. Its latest findings add to evidence that the risks surrounding open source software are changing as AI tools reshape development workflows.

The report argues that the central issue is no longer only whether malware can reach public repositories. It is whether attackers can influence developers' judgment at the point where software choices are made, with one in four malicious packages now using sophisticated techniques such as obfuscation and multi-stage droppers.