procwirenpm
procwire is a confirmed malicious npm package (MAL-2026-6687) that opens a backdoor for remote access (malicious versions 1.3.0, 2.0.0). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in procwire (npm)
What this malware does
On Windows, installing [email protected] automatically downloads and executes an attacker-controlled executable. The package.json preinstall script runs lib/setup.js, which platform-gates to win32, then constructs a download URL by XOR-decoding values pulled from two floating-version sibling packages (endpointmap: "*" and bytecraft: "*") — splitting the C2/payload reference across separate packages so it can be rotated post-publication without modifying procwire itself. lib/worker.js obfuscates every sensitive identifier through String.fromCharCode.apply(null, [...]) arrays — the strings 'https', 'child_process', 'spawn', 'curl.exe', 'bitsadmin', 'powershell.exe', 'cmd.exe', ':Zone.Identifier', the fake update filename prefixes, and the Microsoft-Delivery-Optimization/10.0 User-Agent are all assembled at runtime to defeat static analysis. The download uses a three-tier fallback (Node https, curl.exe, bitsadmin) with TLS verification disabled (rejectUnauthorized: false) and ranged-resume support, saves the binary to %LOCALAPPDATA%\Temp under names such as msedge_update_*.exe, chrome_installer_*.exe, or teams_update_*.exe, strips the Mark-of-the-Web :Zone.Identifier alternate data stream to bypass SmartScreen, then spawns the executable hidden and detached (detached: true, stdio: 'ignore', windowsHide: true). The advertised purpose of procwire is a process-IPC library, which has no need to fetch or execute any external binary. The combination — preinstall lifecycle hook, win32 gating, split-payload URL via wildcard siblings, identifier obfuscation, TLS-verify disabled, fake update filenames, MOTW stripping, hidden execution — is unambiguous malware behavior.
Any computer that has this package installed or running should be considered fully compromised. All secrets and keys stored on that computer should be rotated immediately from a different computer. The package should be removed, but as full control of the computer may have been given to an outside entity, there is no guarantee that removing the package will remove all malicious software resulting from installing it.
Malicious versions
Indicators of compromise (SHA-256)
Detection & response playbook
Backdoor / remote accessFind it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for procwire (2 malicious versions). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging procwire across your stack and pipelines.
If you installed it — respond
procwire establishes remote access, so treat any host that installed it as fully compromised. Isolate the machine, remove the package, rotate all credentials it could reach, and rebuild from a trusted image rather than cleaning in place — a backdoor may have planted additional persistence.
Did it already run?
If procwire was ever installed, its post-install/runtime payload may have already executed. O3's L7 egress monitoring and runtime eBPF sensors detect the credential exfiltration or command-and-control callback after install and block the malicious outbound channel, so you catch and contain the actual compromise — not just the presence of the package.
How O3 protects you
O3 blocks procwire before install through its supply-chain scanner, and if it has already run, detects and severs the exfiltration or C2 callback at runtime through L7 egress monitoring and eBPF.
Frequently asked questions
Campaign
References
Credits
- Amazon Inspector · finder
- ReversingLabs · finder
Detect & block this
O3 blocks procwire-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the C2 callback and severs the channel.