Glassworm Supply-Chain Attack Hides Malicious Code in Invisible Unicode

Researchers reported a software supply-chain campaign attributed to Glassworm that hid malicious JavaScript inside invisible Unicode characters embedded in GitHub repositories, with the activity also spreading to npm and the VS Code Marketplace. Aikido Security identified at least 151 compromised GitHub repositories, with infections observed between March 3 and March 9, and warned the visible set was likely incomplete because some repositories had already been removed. The technique abuses Unicode Private/Variation Selector ranges such as 0xFE00-0xFE0F and 0xE0100-0xE01EF, causing malicious content to appear as blank space to human reviewers and many code-inspection workflows.

The hidden payload is decoded at runtime and executed through eval(), allowing attackers to conceal a full second-stage loader inside apparently empty strings. Reporting on the campaign says prior Glassworm activity used the decoded script to retrieve follow-on malware via the Solana blockchain as a command-and-control channel, enabling theft of tokens, credentials, and secrets. The attack is notable because the Unicode characters are effectively invisible in editors and terminals, undermining manual review and some static analysis, and because it targeted trusted developer distribution channels rather than end users directly.