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Malicious AUR Packages Impersonating yay and paru Run a Remote Script as Root, Raising a Fresh Alarm Over the Arch User Repository

An account named marchos1as uploaded typosquatted yay and paru lookalikes to the AUR; their install scriptlets ran a downloaded script as root before maintainers banned the account.

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Overview

A threat actor uploaded malicious packages to the Arch User Repository (AUR) that impersonated two popular helper tools, yay and paru, according to BleepingComputer. The AUR team banned the account behind the upload and removed the packages, the outlet reported. Help Net Security described the case as one in which Arch Linux users who mistyped yay or paru while installing the helpers may have given a stranger root access to their machine.

What We Know

  • The target. The AUR is a community-maintained package index for Arch Linux and derivative distributions that hosts package build scripts (PKGBUILDs) for third-party and proprietary tools, beta versions, or older versions no longer available through official channels, per BleepingComputer. Yay and paru are known as AUR helpers: Help Net Security says they search the AUR for software and then build, install and update it on the user’s machine.
  • Detection. BleepingComputer reports the latest campaign was detected on October 13 and involved packages uploaded by a user named “marchos1as” under typosquatted names mimicking the yay and paru command-line tools. Help Net Security says that on Tuesday, user James Smith warned the aur-general mailing list that the account had “typo squated popular packages eg yay/paru.” The subject line of Smith’s message claimed that hundreds of packages had been mass uploaded with malware, according to Help Net Security.
  • The mechanism. Andreas Reichel, who maintains packages on the AUR, ran one package, named “yyay,” through a malware scanner; per Help Net Security, the scanner flagged it as malicious with 99% confidence and blocked the build. Reichel wrote that the package “presents itself as a straightforward repackaging of the legitimate ‘yay’ AUR helper (same upstream URL, same source tarball), but the package name ‘yyay’ and the malicious install scriptlet reveal it is a trojanised impersonation designed to blend in with the real package.” BleepingComputer adds that community members confirmed the packages contained legitimate upstream code combined with a malicious installation script that executed a remote shell script with root privileges.
  • Concealment. The attacker left the usual install functions empty so the file would look harmless at a glance and placed the malicious command outside them, as reported by Help Net Security, which quotes Reichel describing the trick as “a structural deception aimed at casual reviewers and automated scanners.”
  • The payload source. Help Net Security says the downloaded script came from a personal project on the code hosting site gitflic.ru. BleepingComputer says Reichel stated that the payload was fetched through a Wayback Machine URL that pointed to a personal repository (hellscripter/install-scripts) hosted on the Russian hosting service GitFlic.
  • Response. Less than an hour after Smith’s report, another AUR maintainer, DeepChirp, replied that a check had confirmed malicious payloads in the installation scripts of the packages and noted: “I have banned the user and deleted all of their packages,” according to Help Net Security. In a follow-up message, Reichel said he would block Russian domains “for the time being,” the outlet reported, adding that he said some of the best developers he knows are from Russia.
  • Guidance. BleepingComputer says Arch users who downloaded the suspicious packages should assume that their systems were compromised and take immediate remediation action.

A Pattern of Incidents

Both outlets place the episode in a run of AUR security problems. BleepingComputer says the repository recently became a target of malicious campaigns, including a June attack in which 400 packages distributed credential-stealing malware with rootkit capabilities, and a July campaign that prompted Arch to temporarily disable package adoption. Help Net Security describes the June incident differently: attackers took over abandoned AUR packages and changed their build instructions to install a malicious npm package, in a campaign researchers estimated may have affected around 1,500 packages. The two outlets therefore give different scale figures for the June campaign. Help Net Security adds that in late July another wave of malware led Arch to suspend package adoption, and days later the project stopped all uploads to the AUR.

What We Don’t Know

  • Link to an npm worm. BleepingComputer notes that an application security company, SafeDep, documented an npm campaign dubbed “DirtyBlanket” that fetched code from a ‘hellscripter/install-scripts’ repository on Codeberg, and that an OSV advisory on that activity describes the same Wayback Machine and GitFlic domain. Despite the connections, the outlet says, there is currently no confirmation that the two operations are related.
  • Number of affected machines. Neither report states how many users installed the lookalike packages before removal. Smith’s subject line referred to hundreds of packages, but the articles do not give a verified package count for this campaign.
  • What the script delivered. Reichel’s warning, as quoted by Help Net Security, listed credential theft, backdoor installation and rootkit deployment as possibilities for whatever the remote script served at the time. The reports do not establish which final payload, if any, reached victims.

Analysis

The incident illustrates a structural property of user-submitted build-script repositories visible in both reports: an install scriptlet runs with root privileges, so a single mistyped helper name can be enough to hand control to an attacker. In this case the alarm came from community members on a mailing list, and per Help Net Security a maintainer confirmed the malicious payloads and banned the account less than an hour after the first report, rather than an upload-side control stopping the packages. Whether Arch adds upload-side controls after the June and July incidents is not addressed in either source.