Malicious npm package ‘fallguys’ removed from the official repository

The npm security team removed a malicious JavaScript library from the npm repository that was designed to steal sensitive files from the victims.

The npm security team has removed the JavaScript library “fallguys” from the npm portal because it was containing a malicious code used to steal sensitive files from an infected users’ browser and Discord application.

The fallguys library claimed to provide an interface to the “Fall Guys: Ultimate Knockout” game API. The package was available the repository for two weeks and was downloaded nearly 300 times.

“fallguys contained malicious code that attempted to read local sensitive files and exfiltrate information through a Discord webhook.” reads the npm’s advisory.

Every project that integrated the malicious library, upon execution will get the malicious code executed.

Experts noticed that the malicious package was designed to steal only specific sensitive information from the infected developers’ systems.

This malicious code would attempt to access the content of the following five local files and then post the data inside a Discord channel:

/AppData/Local/Google/Chrome/User\x20Data/Default/Local\x20Storage/leveldb
/AppData/Roaming/Opera\x20Software/Opera\x20Stable/Local\x20Storage/leveldb
/AppData/Local/Yandex/YandexBrowser/User\x20Data/Default/Local\x20Storage/leveldb
/AppData/Local/BraveSoftware/Brave-Browser/User\x20Data/Default/Local\x20Storage/leveldb
/AppData/Roaming/discord/Local\x20Storage/leveldb

The first four files are LevelDB databases used common browsers like Chrome, Opera, Yandex Browser, and Brave. The files contain a user’s browsing history data.

The /AppData/Roaming/discord/Local\x20Storage/leveldb file is a sort of LevelDB database for the Discord Windows client that is used to store information on the channels a user has joined.

Experts speculate the malicious package was used to gather information on developers using it, such as the sites they were accessing.

“Remove the package from your system and ensure any compromised credentials are rotated.” concludes the advisory.

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Pierluigi Paganini

(SecurityAffairs – hacking, npm)

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Pierluigi Paganini

Pierluigi Paganini is member of the ENISA (European Union Agency for Network and Information Security) Threat Landscape Stakeholder Group and Cyber G7 Group, he is also a Security Evangelist, Security Analyst and Freelance Writer. Editor-in-Chief at "Cyber Defense Magazine", Pierluigi is a cyber security expert with over 20 years experience in the field, he is Certified Ethical Hacker at EC Council in London. The passion for writing and a strong belief that security is founded on sharing and awareness led Pierluigi to find the security blog "Security Affairs" recently named a Top National Security Resource for US. Pierluigi is a member of the "The Hacker News" team and he is a writer for some major publications in the field such as Cyber War Zone, ICTTF, Infosec Island, Infosec Institute, The Hacker News Magazine and for many other Security magazines. Author of the Books "The Deep Dark Web" and “Digital Virtual Currency and Bitcoin”.