proc-macro1

Poisoned Rust Crates Execute Malware at Build Time: 245 Million Downloads Hit in Supply-Chain Attack

Three widely used Rust crates on crates.io were poisoned on August 20 with malicious versions that execute automatically during cargo build. The attack leveraged a typosquatted proc-macro1 dependency containing a build script that downloads payloads and establishes persistence. arrayref alone has accumulated 245 million downloads and is pulled automatically through caret ranges in many dependency trees. Attack infrastructure overlaps with prior campaigns attributed to Sapphire Sleet and MIDNIGHT NEPTUNE. Rust security teams yanked the malicious releases within 86-107 minutes, but the incident highlights missing publish-age controls and weak maintainer-account protections in the Cargo ecosystem.