YARA Performance Tuning for Large-Scale Scanning

When scanning thousands of files across an enterprise, YARA performance becomes critical. Here are battle-tested techniques for keeping your scans fast.

String Optimization

The most impactful optimization is in your string definitions. Prefer hex strings over text when possible:

rule Optimized_Detection {
    strings:
        // Faster: hex pattern
        $hex = { 4D 5A 90 00 03 00 00 00 }
        
        // Slower: wide string with modifiers
        $text = "suspicious" wide ascii nocase
    
    condition:
        $hex and $text
}