User-Agent String (Suspicious Patterns) Regex for JavaScript

What this pattern does

This page provides a comprehensive, battle-tested regular expression for matching user-agent string (suspicious patterns), ported and verified for JavaScript. In security-sensitive code, using an unverified regex can open the door to both false positives and denial-of-service attacks. The snippet below is ready to drop into your JavaScript project — whether you're validating in an Express middleware, a Next.js API route, or a client-side form.

Javascript Implementation

// User-Agent String (Suspicious Patterns)
// ReDoS-safe | RegexVault — Security > Network Security

const useragentStringSuspiciousPatternsRegex = /(?:sqlmap|nmap|masscan|nikto|nessus|openvas|nuclei|burpsuite|zap|dirbuster|gobuster|ffuf|wfuzz|hydra|metasploit|msfconsole|python-requests|curl|wget|libwww-perl|scrapy|mechanize|go-http-client|[Bb]ot|[Cc]rawler|[Ss]pider|[Ss]craper|PhantomJS|HeadlessChrome)(?:[\/\s]|$)/i;

function validateUseragentStringSuspiciousPatterns(input: string): boolean {
  return useragentStringSuspiciousPatternsRegex.test(input);
}

// Example
console.log(validateUseragentStringSuspiciousPatterns("sqlmap/1.4.12")); // true

Test Cases

When to use this pattern

This pattern is drawn from the Security > Network Security category and carries a ReDoS-safe certification. That matters for JavaScript developers because especially critical in long-running Node.js event loops where a ReDoS vulnerability can block the entire process. RegexVault audits patterns against known backtracking attack vectors, ensuring you have the necessary context before using this regex in a high-stakes production environment.

Common Pitfalls

Technical Notes

Detection pattern for WAF (Web Application Firewall) rules. Matches known scanner, pentesting tool, and automation library user agents. False positives: legitimate bots (Googlebot, Bingbot) are not included. Extend the list based on observed attack patterns in your logs.