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Short answer: Treat a machine that allowed malware to run as root as fully compromised. Disconnect it immediately, preserve volatile memory only if a legitimate forensic investigation requires it, then reinstall Arch Linux from a freshly downloaded and verified official image. Copy back only reviewed user data, rebuild system configuration, and rotate every credential that may have existed on the host.
Why root access changes the recovery decision
Root is the highest normal privilege on an Arch Linux installation. Malware that obtained it may alter system files, startup components, accounts, logs, package data, and other mechanisms used to inspect the machine. A rootkit can also conceal processes or files from tools running inside the affected installation. That means a clean-looking process list, directory listing, or malware scan is not proof that the system is clean.
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The Cloud Security Alliance’s 2026 response note states: “For systems where the malicious package ran as root, or where subsequent investigation cannot confirm that root privileges were absent, the system should be treated as fully compromised.” Its recommended response is to preserve volatile memory when forensic analysis is planned and then reinstall from trusted media.
Removing the suspected AUR package is therefore not a trust reset. Even if the package directory disappears, you cannot establish from the compromised operating system that it did not add another account, alter a service, replace a binary, capture credentials, or leave persistence elsewhere. The safe objective is to replace the operating system and restore only material you have reviewed.
#1 Best Overall
Contain the machine before investigating
- Disconnect network access. Unplug Ethernet, disable Wi-Fi, and remove the computer from remote-management systems and shared networks. If it is a server, isolate its switch port or security-group access. Physical disconnection is preferable to relying on commands issued inside a potentially deceptive installation.
- Record the incident. Write down the current time, the suspected package or entry point, who noticed it, connected systems, and any visible symptoms. Do not edit or delete files while deciding whether evidence must be preserved.
- Stop using the host for sensitive work. Do not log in to email, cloud consoles, source-control services, payment systems, or other important accounts from it. Assume that passwords, browser sessions, SSH keys, API tokens, and files available to the host may have been exposed.
- Decide whether evidence has legal or business value. A regulated environment, business-critical service, valuable intellectual property, or possible criminal activity may require an incident-response specialist. Do not reboot such a machine until the evidence decision is made.
If you need only to recover a personal workstation and no forensic case exists, shut it down after isolation. Prepare the recovery environment on a different, known-clean computer.
Choose forensic preservation or an immediate rebuild
The right first action depends on whether proving what happened matters more than returning the machine to service quickly. Both paths end with a clean installation when root execution is confirmed or cannot be ruled out.
| Situation | First action | What happens next |
|---|---|---|
| Regulated, business-critical, high-value, or potentially criminal incident | Keep the host isolated and consult incident-response specialists. Preserve volatile memory before shutdown if they direct you to do so. | Acquire evidence using a documented process, then rebuild from trusted media after the investigation permits it. |
| Personal system with no need for formal forensics | Disconnect it, record the basic facts, and power it off. | Use a clean computer and verified Arch media to copy selected data and reinstall. |
| Uncertainty about whether root privileges were reached | Use the fully compromised path. | Do not rely on package removal or an in-place scan; preserve evidence if required, then reinstall. |
Volatile memory can contain information that disappears at shutdown, so preserving it is a specialist task when the evidence is important. If no such investigation is required, leaving the compromised system powered on only increases the time malware has to communicate or damage data.
Prepare trusted Arch recovery media
Use a separate clean computer
Download the official Arch Linux ISO from a computer you trust. Do not download it from the compromised host, and do not use an image that has been sitting on an untrusted system without verifying it again. Arch documents USB media as suitable for installation, system maintenance, and recovery.
Rank #2
Verify the ISO before writing it
Verify the published checksum or cryptographic signature using the instructions provided with the current Arch release. A successful verification confirms that the file you received matches the publisher’s release; it does not make an old or previously modified copy trustworthy. If verification fails, discard the file and obtain it again from the official distribution channel.
Write and control a dedicated USB drive
Write the verified image to a dedicated USB flash drive. The imaging process erases the drive, so select the device carefully. Label it with the release date, keep it disconnected when not needed, and do not use it as ordinary file storage during the incident. An external USB drive is useful for a second, separate copy of recovered data; keep that backup disconnected from the suspect host except while copying through the trusted live environment.
Recover files without carrying the compromise forward
Boot the affected computer from the verified Arch USB, not from its installed system. From the live environment, mount old filesystems read-only wherever practical. For example, after identifying the correct partition with the live system’s disk tools, a read-only mount can look like this:
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sudo mount -o ro,nosuid,nodev,noexec /dev/DEVICE /mnt/oldReplace /dev/DEVICE with the correct partition. The options reduce the chance of accidentally executing content while you inspect it, but they do not make files safe. If the disk is encrypted, unlock it only from the trusted live environment and continue to treat the contents as untrusted.
Copy only data you can identify
Copy documents, photographs, project source, exported mail, and other user-created data to separate storage. Select folders and files deliberately rather than copying an entire home directory or the old root filesystem. Scan the copied data from a clean, updated system before opening it, and quarantine anything unexpected.
Use the old installation as a reference, not a template
Arch’s installation guidance recommends recording information such as user data, mail, web-server content, hostnames, DNS settings, SSH keys, hardware details, and boot-loader configuration before replacing a system. Preserve those items as notes or quarantined reference material. Re-enter the values manually on the new installation instead of restoring the old system tree.
| Material | Recovery treatment |
|---|---|
| Documents, photos, source files, and other clearly identified user data | Copy to separate storage, scan from a clean system, and restore selectively. |
| Mail stores and web-server content | Preserve what is needed, inspect it, and restore only reviewed files. Treat uploads and scripts as untrusted. |
| Shell startup files, browser profiles, editor extensions, and dotfiles | Review line by line. Recreate configuration where possible; browser profiles may contain active session tokens. |
| Cron entries, systemd units, initramfs files, boot-loader files, package databases, and system binaries | Do not copy them into the new system. Recreate services and boot configuration from trusted packages and documented settings. |
| SSH private keys, API credentials, signing keys, and unknown archives | Keep only for forensic reference if necessary. Assume secrets are exposed and generate replacements. |
| Package build directories and AUR PKGBUILDs | Do not build from the old copies. Obtain fresh sources and review every PKGBUILD and install script before use. |
Do not restore an old /etc, /usr, /var, or complete home directory wholesale. A hidden executable, startup file, service definition, or browser credential can recreate the incident after an apparently successful reinstall.
Reinstall Arch Linux from trusted media
A reinstall is the trust reset. Use the current Arch installation procedure for the release you downloaded; partitioning and boot-loader details vary with firmware mode, disk layout, encryption, and hardware.
Rank #4
- Boot the verified USB. Select the USB in the firmware boot menu and remain in the live environment. Keep the machine disconnected from networks until networking is needed for installation or updates.
- Identify the target disk carefully. Confirm the disk model and partition layout before changing anything. If the old installation is being replaced, plan to format the old root and system partitions rather than installing over unknown files.
- Partition and format the target. Create the layout appropriate for the computer, firmware, encryption plan, and backup requirements. Do not leave the old root filesystem mounted as the new system’s root.
- Install the base system from the trusted ISO. Install only the packages required for the initial boot and administration. Obtain additional packages after the new system is online and fully updated.
- Configure the essentials. Set locale, time zone, hostname, users, passwords, networking, and access controls. Create a normal user for daily work and reserve root for administration.
- Install and configure the boot loader. Re-enter the boot configuration from your notes rather than copying old boot files. Rebuild the initramfs whenever the installation procedure or your hardware configuration requires it.
- Boot the new installation and update it. Remove the USB after shutdown or when the installer instructs you to do so, boot the new root filesystem, connect through a trusted network, and apply all available updates before restoring applications or data.
- Reinstall applications from trusted sources. Prefer Arch’s official repositories for security-sensitive components. Add AUR software only after reviewing the current PKGBUILD and install scripts.
If the machine uses full-disk encryption or a special storage layout, document the new recovery procedure and test that you can boot it before copying personal data back.
Use chroot only for repair of a trusted installation
ArchWiki describes chroot as a maintenance environment used for tasks such as reinstalling a boot loader, rebuilding an initramfs, and repairing packages. It requires another Linux installation or installation media and root privilege.
Chroot is appropriate when an installation you still trust is merely unbootable or has a damaged package. It is not a disinfectant and does not prove that a compromised root filesystem is clean. Entering the old root from the live USB and running a scanner, package manager, or cleanup script leaves the same trust problem: malware that altered the old installation may hide from or interfere with those tools. After root compromise, use chroot only to extract information needed for recovery or to repair the newly installed, trusted system.
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Rotate from a separate clean device
Change passwords and revoke or replace secrets from a known-clean computer or phone, not from the affected host. Prioritize accounts that could control other systems or publish software.
- Local and remote login passwords
- SSH key pairs and authorized-key entries
- API tokens, cloud credentials, deployment keys, and service-account secrets
- Source-control, package-publishing, database, and infrastructure credentials
- Browser sessions and saved passwords
- Signing keys and recovery codes associated with important accounts
Revoke the old credentials before or at the same time as issuing replacements. Generate new SSH keys on the clean system or the freshly installed system; do not copy private keys from the compromised disk for convenience. Review external authentication logs for unexpected access and tell administrators or service owners what happened.
Rebuild configuration by hand or from reviewed version control
Recreate services, firewall rules, users, scheduled jobs, and application settings from documentation or a version-controlled source you have reviewed. Do not blindly restore old system configuration. Restore user data only after scanning it and confirming that the files are expected.
Harden the replacement system
Keep a recovery baseline
- Fully update the new installation before normal use.
- Keep an offline rescue USB made from a verified official image.
- Maintain a package inventory from the clean system. For example, after installation you can record explicitly installed packages with
pacman -Qqe > package-list.txt. - Back up important data to offline or otherwise isolated storage and test that a restore works.
- Document disk layout, encryption recovery information, hostnames, DNS, boot-loader settings, and hardware details.
ArchWiki summarizes the reason for this preparation: “Backups are essential for security because they enable recovery from ransomware, data corruption, accidental deletion, and system compromise without permanent data loss.”
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The Arch Linux notice dated June 12, 2026 reported a high volume of malicious AUR package adoptions and updates and urged users to review PKGBUILD and install-script changes. It specifically said: “We continue to encourage all users of AUR packages to review all PKGBUILD and install script changes when updating, especially during this time.”
| Source choice | Provenance and review | Practical rule after an incident |
|---|---|---|
| Official Arch repositories | Packages are distributed through Arch’s official infrastructure and are the simpler choice for security-sensitive components. | Prefer them when they meet the requirement; keep the system updated. |
| AUR | User-contributed PKGBUILDs and install scripts require your own review. A package’s popularity is not proof of safety. | Inspect every change before building, obtain fresh source material, and avoid restoring old build directories. |
Keep a record of why each AUR package is installed and who maintains the project. If you cannot review the build instructions or do not need the software, leave it out of the rebuilt system.
Quick Recap
Common recovery mistakes and their fixes
- “I removed the bad package, so I am done.” Root execution means other changes may remain. Reinstall when root compromise is confirmed or cannot be excluded.
- Running scanners on the installed system. A rootkit may hide the evidence those scanners need. Inspect from trusted media and use a specialist when forensics matter.
- Reusing passwords or keys because the files look intact. Treat every credential present on the host as exposed and rotate it from a clean device.
- Copying the old root filesystem or all of
/home. Restore selected, reviewed data instead of executables, startup files, services, and unknown archives. - Using chroot as a cleaning tool. Chroot repairs a trusted installation; it cannot establish trust in a compromised one.
- Connecting the suspect host before recovery is complete. Keep it isolated until it has been rebuilt, updated, and had its credentials replaced.
- Destroying evidence before deciding whether it is needed. If legal, regulatory, or business requirements apply, preserve volatile memory through qualified responders before shutdown.
Recovery checklist
- Isolate Ethernet, Wi-Fi, remote management, and shared-network access.
- Record the suspected entry point, time, affected accounts, and connected systems.
- Decide whether forensic preservation is required; if so, involve specialists before powering off.
- On a clean computer, download and verify the official Arch ISO.
- Write the ISO to a dedicated USB and keep the media controlled.
- Boot the affected machine from that media and mount old filesystems read-only where practical.
- Copy only identified user data to separate storage; quarantine and scan it from a clean system.
- Record configuration facts without restoring old system files, services, binaries, or credentials.
- Partition and format the target, install Arch from the verified media, configure it, install the boot loader, and rebuild the initramfs as required.
- Update the new system, reinstall applications from trusted sources, and review every AUR build script.
- Restore selected data, recreate configuration, generate new keys, and revoke old credentials.
- Set up tested backups, a package inventory, and a controlled rescue USB before returning the machine to normal service.
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