500ms to midnight: XZ A.K.A. liblzma backdoor

On March 29, 2024, malicious, obfuscated commits were discovered in XZ Utils (liblzma) versions 5.6.0 and 5.6.1 that introduce a backdoor able to bypass SSH authentication and execute code in a pre-auth context; the report describes the three-stage malicious build process, available YARA and EQL detection rules, osquery queries and remediation guidance, and notes limited distribution of impacted builds but high potential impact if deployed.