proc-macro-encrates.io
proc-macro-en is a confirmed malicious crates.io package (MAL-2026-14339) that opens a backdoor for remote access. Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in proc_macro_en (crates.io)
What this malware does
proc-macro-en is a malicious crate published to crates.io as part of the coordinated build-time payload campaign on 2026-08-20 that trojanized arrayref, internment, and append-only-vec and published the proc-macro1 typosquat of proc-macro2. It was used as an attacker-controlled dependency carrying a build-script payload; building it results in the download and execution of a remote binary from https://23.254.165.112:9089/ with 23.254.165.112:443 as command and control. All versions have been removed from crates.io. The individual build script of this crate was not analyzed directly; its behavior is attributed from the campaign.
Malicious versions
Every published version of this package is considered malicious — remove it entirely.
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 proc-macro-en (all published versions). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging proc-macro-en across your stack and pipelines.
If you installed it — respond
proc-macro-en 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 proc-macro-en 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 proc-macro-en 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
References
Credits
- SafeDep · finder
- jhobern · reporter
Detect & block this
O3 blocks proc-macro-en-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the C2 callback and severs the channel.