A recent report released on April 2 has uncovered a worrying rise in open-source malware aimed at developers. These attacks, described as “smash and grab” operations, are designed to swiftly exfiltrate sensitive data from development environments.
Brian Fox, co-founder and CTO of Sonatype, explained that developers are increasingly falling victim to deceptive software packages. Once installed, these packages execute malicious code to harvest confidential data such as API keys, session cookies, and database credentials—then transmit it externally.
“It’s over in a flash,” Fox said. “Many of the times, people don’t recognize that this was even an attack.”
Sonatype, a leader in software supply-chain security, revealed that 56% of malware identified in Q1 2025 focused on data exfiltration. These programs are tailored to extract sensitive information from compromised systems. This marks a sharp increase from Q4 2024, when only 26% of open-source threats had such capabilities. The company defines open-source malware as “malicious code intentionally crafted to target developers in order to infiltrate and exploit software supply chains.”
Fox emphasized that these attacks often begin with spear phishing tactics—posing as legitimate software packages on public repositories. Minor changes, such as replacing hyphens with underscores in filenames, can mislead even seasoned developers.
“The attackers fake the number of downloads. They fake the stars so it can look as legit as the original one, because there’s not enough awareness. [Developers] are not yet trained to be skeptical,” Fox told us.
These stolen data fragments—while small—can have massive consequences. API keys, hashed passwords, and cookie caches serve as backdoors for broader attacks.
“They’re breaking into the janitor’s closet, not to put in a bomb, but to grab his keychain, and then they’re going to come back at night with the keychain,” Fox said.
The 2025 report highlights early examples:
Compromised JavaScript packages on npm were found to steal environment variables, which typically contain API tokens, SSH credentials, and other sensitive information.
A fake npm extension embedded spyware that enabled complete remote access.
Malicious packages targeted cryptocurrency developers, deploying Windows trojans capable of keylogging and data exfiltration. These packages had over 1,900 downloads collectively.
A separate report published by Sonatype in November 2024 reported a 156% year-over-year surge in open-source malware. Since October 2023, over 512,847 malicious packages have been identified—including but not limited to data-exfiltrating malware.