Description

Detects potential Regular Expression Denial of Service (ReDoS) vulnerabilities in Scala code where untrusted input could be used in regular expressions. ReDoS attacks can cause severe performance issues by exploiting poorly constructed regular expressions to cause exponential evaluation time.

Detection Strategy

• Identifies creation of regex pattern objects that may process untrusted input

• Detects calls to regex matching methods that could handle untrusted data

• Reports when regular expressions are used without proper input validation or sanitization

• Checks for common regex pattern compilation and matching methods in Scala

• Focuses on both direct regex object creation and method calls that process regular expressions

Vulnerable code example

import scala.util.matching.Regex

class RegexController {
  def processUserInput(pattern: String, input: String): Boolean = {
    // VULNERABLE: Directly using untrusted user input as regex pattern can lead to ReDoS
    val regex = new Regex(pattern)
    regex.findFirstIn(input).isDefined
  }...

✅ Secure code example

import scala.util.matching.Regex
import java.util.regex.Pattern

class RegexController {
  def processUserInput(pattern: String, input: String): Boolean = {
    // Secure: Escape untrusted pattern using Pattern.quote to prevent ReDoS
    val safePattern = Pattern.quote(pattern)
    val regex = new Regex(safePattern)...