GlassWorm Returns with 24 Malicious Extensions Impersonating Popular Developer Tools
Summary:
The ongoing GlassWorm supply chain attack, which began in mid-October 2025, resurfaced in late November with new packages that successfully infiltrated both the Microsoft VS Marketplace and Open VSX, introducing 24 malicious extensions, doubling the total extension count from when it was initially discovered. These extensions impersonate popular developer tools and frameworks, including Flutter, React, Tailwind, Vim, and Vue, and are designed to steal sensitive credentials and cryptocurrency assets. The GlassWorm campaign previously utilized the Solana blockchain for C2. It has been observed harvesting credentials for npm, Open VSX, GitHub, and Git, draining crypto wallets, and turning compromised developer machines into attack nodes; a comprehensive approach to using the compromise.
In this latest wave, spotted by Secure Annex's John Tuckner, the attackers employed SEO techniques to make the extensions appear trustworthy, such as inflating download counts to achieve high search rankings near the legitimate tools, similarly to the previous waves. In the new iteration, one of the extensions analyzed contained Rust-based implants (a Windows DLL, os.node, and a macOS dynamic library, darwin.node) that fetch C2 server details from a Solana blockchain wallet or, as a backup, can parse a Google Calendar event for the details. This new iteration still relies on the invisible Unicode trick.
Security Officer Comments:
The dual use of two major marketplaces for 24 extensions in a single wave demonstrates a sophisticated threat actor. The attackers leverage a weakness where the extension can be updated with new malicious code right after the initially presented extension is approved, easily evading filters. The flexible shift to Rust implants and backup options for fetching the C2 server details showcases the agility of this operation. Developers must treat all third-party extensions with extreme scrutiny, as the attackers are nefariously inflating trust metrics and leveraging weaknesses in the approval process to deploy malware.
Suggested Corrections:
Threat actors employ different techniques to execute software supply chain attacks. Three common techniques are:
“Most modern software receives routine updates to address bugs and security issues. Software vendors typically distribute updates from centralized servers to customers as a routine part of product maintenance. Threat actors can hijack an update by infiltrating the vendor’s network and either inserting malware into the outgoing update or altering the update to grant the threat actor control over the software’s normal functionality. For example, the NotPetya attack occurred in 2017 when Russian hackers targeting Ukraine spread malware through tax accounting software popular in Ukraine. What would later be called the NotPetya malware spread well beyond Ukraine and caused major global disruptions in crucial industries, including international shipping, financial services, and healthcare” (CISA, 2022)
Undermining Codesigning
“Codesigning is used to validate the identity of the code’s author and the integrity of the code. Attackers undermine codesigning by self-signing certificates, breaking signing systems, or exploiting misconfigured account access controls. By undermining codesigning, threat actors are able to successfully hijack software updates by impersonating a trusted vendor and inserting malicious code into an update. For example, APT 41, a China-based threat actor, routinely undermines codesigning while conducting sophisticated software supply chain compromises against the United States and other countries” (CISA, 2022)
Compromising Open-Source Code
“Open-source code compromises occur when threat actors insert malicious code into publicly accessible code libraries, which unsuspecting developers—looking for free blocks of code to perform specific functions—then add into their own third-party code. For example, in 2018, researchers discovered 12 malicious Python libraries uploaded on the official Python Package Index (PyPI). The attacker used typosquatting tactics by creating libraries titled “diango,” “djago,” “dajngo,” etc., to lure developers seeking the popular “django” Python library. The malicious libraries contained the same code and functionality of those they impersonated; but they also contained additional functionality, including the ability to obtain boot persistence and open a reverse shell on remote workstations. Open-source code compromises can also affect privately owned software because developers of proprietary code routinely leverage blocks of open-source code in their products” (CISA, 2022)
“Network defenders are limited in their ability to quickly mitigate consequences after a threat actor has compromised a software supply chain. This is because organizations rarely control their entire software supply chain and lack authority to compel every organization in their supply chain to take prompt mitigation steps. Due to the difficulty of mitigating consequences after a software supply chain attack occurs, network defenders should observe industry best practices before an attack has occurred. Implementing best practices will bolster an organization’s ability to prevent, mitigate, and respond to such attacks” (CISA, 2022)
NIST suggests eight key practices for establishing a NIST C-SCRM (Cyber Supply Chain Risk Management) approach that can be applied to software.
https://www.cisa.gov/sites/default/files/publications/defending_against_software_supply_chain_attacks_508_1.pdf
Link(s):
https://thehackernews.com/2025/12/glassworm-returns-with-24-malicious.html
https://secureannex.com/blog/glassworm-continued/
The ongoing GlassWorm supply chain attack, which began in mid-October 2025, resurfaced in late November with new packages that successfully infiltrated both the Microsoft VS Marketplace and Open VSX, introducing 24 malicious extensions, doubling the total extension count from when it was initially discovered. These extensions impersonate popular developer tools and frameworks, including Flutter, React, Tailwind, Vim, and Vue, and are designed to steal sensitive credentials and cryptocurrency assets. The GlassWorm campaign previously utilized the Solana blockchain for C2. It has been observed harvesting credentials for npm, Open VSX, GitHub, and Git, draining crypto wallets, and turning compromised developer machines into attack nodes; a comprehensive approach to using the compromise.
In this latest wave, spotted by Secure Annex's John Tuckner, the attackers employed SEO techniques to make the extensions appear trustworthy, such as inflating download counts to achieve high search rankings near the legitimate tools, similarly to the previous waves. In the new iteration, one of the extensions analyzed contained Rust-based implants (a Windows DLL, os.node, and a macOS dynamic library, darwin.node) that fetch C2 server details from a Solana blockchain wallet or, as a backup, can parse a Google Calendar event for the details. This new iteration still relies on the invisible Unicode trick.
Security Officer Comments:
The dual use of two major marketplaces for 24 extensions in a single wave demonstrates a sophisticated threat actor. The attackers leverage a weakness where the extension can be updated with new malicious code right after the initially presented extension is approved, easily evading filters. The flexible shift to Rust implants and backup options for fetching the C2 server details showcases the agility of this operation. Developers must treat all third-party extensions with extreme scrutiny, as the attackers are nefariously inflating trust metrics and leveraging weaknesses in the approval process to deploy malware.
Suggested Corrections:
Threat actors employ different techniques to execute software supply chain attacks. Three common techniques are:
- Hijacking updates
- Undermining code signing
- Compromising open-source code
“Most modern software receives routine updates to address bugs and security issues. Software vendors typically distribute updates from centralized servers to customers as a routine part of product maintenance. Threat actors can hijack an update by infiltrating the vendor’s network and either inserting malware into the outgoing update or altering the update to grant the threat actor control over the software’s normal functionality. For example, the NotPetya attack occurred in 2017 when Russian hackers targeting Ukraine spread malware through tax accounting software popular in Ukraine. What would later be called the NotPetya malware spread well beyond Ukraine and caused major global disruptions in crucial industries, including international shipping, financial services, and healthcare” (CISA, 2022)
Undermining Codesigning
“Codesigning is used to validate the identity of the code’s author and the integrity of the code. Attackers undermine codesigning by self-signing certificates, breaking signing systems, or exploiting misconfigured account access controls. By undermining codesigning, threat actors are able to successfully hijack software updates by impersonating a trusted vendor and inserting malicious code into an update. For example, APT 41, a China-based threat actor, routinely undermines codesigning while conducting sophisticated software supply chain compromises against the United States and other countries” (CISA, 2022)
Compromising Open-Source Code
“Open-source code compromises occur when threat actors insert malicious code into publicly accessible code libraries, which unsuspecting developers—looking for free blocks of code to perform specific functions—then add into their own third-party code. For example, in 2018, researchers discovered 12 malicious Python libraries uploaded on the official Python Package Index (PyPI). The attacker used typosquatting tactics by creating libraries titled “diango,” “djago,” “dajngo,” etc., to lure developers seeking the popular “django” Python library. The malicious libraries contained the same code and functionality of those they impersonated; but they also contained additional functionality, including the ability to obtain boot persistence and open a reverse shell on remote workstations. Open-source code compromises can also affect privately owned software because developers of proprietary code routinely leverage blocks of open-source code in their products” (CISA, 2022)
“Network defenders are limited in their ability to quickly mitigate consequences after a threat actor has compromised a software supply chain. This is because organizations rarely control their entire software supply chain and lack authority to compel every organization in their supply chain to take prompt mitigation steps. Due to the difficulty of mitigating consequences after a software supply chain attack occurs, network defenders should observe industry best practices before an attack has occurred. Implementing best practices will bolster an organization’s ability to prevent, mitigate, and respond to such attacks” (CISA, 2022)
NIST suggests eight key practices for establishing a NIST C-SCRM (Cyber Supply Chain Risk Management) approach that can be applied to software.
- Integrate C-SCRM across the organization.
- Establish a formal C-SCRM program.
- Know and manage critical components and suppliers.
- Understand the organization’s supply chain. software for which a vulnerability is disclosed
- Closely collaborate with key suppliers.
- Include key suppliers in resilience and improvement activities.
- Assess and monitor throughout the supplier relationship.
- Plan for the full lifecycle.
https://www.cisa.gov/sites/default/files/publications/defending_against_software_supply_chain_attacks_508_1.pdf
Link(s):
https://thehackernews.com/2025/12/glassworm-returns-with-24-malicious.html
https://secureannex.com/blog/glassworm-continued/