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const vm = require('vm'); // Zero-dependency VM sandbox
/**
* ReDoSProtector - Protects against Regular Expression Denial of Service attacks
* Updated to use VM sandbox instead of setTimeout for better security
*/
class ReDoSProtector {
constructor() {
this.config = SECURITY_CONFIG;
this.timeout = this.config.REGEX_TIMEOUT;
// Known dangerous regex patterns
this.dangerousPatterns = [
// Exponential backtracking
/(\w+)*$/,
/(a+)+$/,
/(a|a)*$/,
/(a|ab)*$/,
// Nested quantifiers
/(\d+)*\d+/,
/(\w+)+\w+/,
// Overlapping alternations
/(x+x+)+y/,
/(.*.*)*$/
];
}
/**
* Test regex with VM sandbox and timeout
* More secure than setTimeout - actually stops execution
*/
testWithVMSandbox(regex, input, timeoutMs = this.timeout) {
try {
// Create isolated context
const sandbox = {
regex: regex,
input: input,
result: null
};
// Create context
const context = vm.createContext(sandbox);
// Code to execute
const code = 'result = regex.test(input);';
// Run with timeout
const script = new vm.Script(code);
script.runInContext(context, {
timeout: timeoutMs,
displayErrors: true
});
return sandbox.result;
} catch (error) {
if (error.code === 'ERR_SCRIPT_EXECUTION_TIMEOUT') {
throw new ReDoSError(`Regex execution timeout (${timeoutMs}ms): possible ReDoS vulnerability`);
}
throw new ReDoSError(`Regex execution failed: ${error.message}`);
}
}
/**
* Execute regex match with VM sandbox and timeout
*/
matchWithVMSandbox(regex, input, timeoutMs = this.timeout) {
try {
// Create isolated context
const sandbox = {
regex: regex,
input: input,
result: null
};
// Create context
const context = vm.createContext(sandbox);
// Code to execute
const code = 'result = input.match(regex);';
// Run with timeout
const script = new vm.Script(code);
script.runInContext(context, {
timeout: timeoutMs,
displayErrors: true
});
return sandbox.result;
} catch (error) {
if (error.code === 'ERR_SCRIPT_EXECUTION_TIMEOUT') {
throw new ReDoSError(`Regex execution timeout (${timeoutMs}ms): possible ReDoS vulnerability`);
}
throw new ReDoSError(`Regex execution failed: ${error.message}`);
}
}
/**
* Test regex with timeout (Legacy Promise-based - deprecated)
* @deprecated Use testWithVMSandbox instead for better security
*/
testWithTimeout(regex, input, timeoutMs = this.timeout) {
return new Promise((resolve, reject) => {
const timeout = setTimeout(() => {
reject(new ReDoSError(`Regex execution timeout (${timeoutMs}ms): possible ReDoS vulnerability`));
}, timeoutMs);
try {
const result = regex.test(input);
clearTimeout(timeout);
resolve(result);
} catch (error) {
clearTimeout(timeout);
reject(error);
}
});
}
/**
* Execute regex match with timeout (Legacy Promise-based - deprecated)
* @deprecated Use matchWithVMSandbox instead for better security
*/
matchWithTimeout(regex, input, timeoutMs = this.timeout) {
return new Promise((resolve, reject) => {
const timeout = setTimeout(() => {
reject(new ReDoSError(`Regex execution timeout (${timeoutMs}ms): possible ReDoS vulnerability`));
}, timeoutMs);
try {
const result = input.match(regex);
clearTimeout(timeout);
resolve(result);
} catch (error) {
clearTimeout(timeout);
reject(error);
}
});
}
/**
* Check if regex is potentially dangerous
*/
isDangerous(regexPattern) {
const patternStr = regexPattern.toString();
// Check for nested quantifiers
if (/\([^)]*[*+]\)[*+]/.test(patternStr)) {
return {
dangerous: true,
reason: 'Nested quantifiers detected',
pattern: patternStr
};
}
// Check for overlapping alternations with quantifiers
if (/\([^|]*\|[^)]*\)[*+]/.test(patternStr)) {
return {
dangerous: true,
reason: 'Overlapping alternations with quantifiers',
pattern: patternStr
};
}
// Check for repeated groups
if (/\([^)]*[*+][^)]*\)[*+]/.test(patternStr)) {
return {
dangerous: true,
reason: 'Repeated groups detected',
pattern: patternStr
};
}
// Check for catastrophic backtracking patterns
if (/\((?:\.\*)+\)[*+]/.test(patternStr)) {
return {
dangerous: true,
reason: 'Catastrophic backtracking pattern',
pattern: patternStr
};
}
return {
dangerous: false,
pattern: patternStr
};
}
/**
* Analyze regex complexity
*/
analyzeComplexity(regexPattern) {
const patternStr = regexPattern.toString();
const metrics = {
length: patternStr.length,
quantifiers: (patternStr.match(/[*+?{]/g) || []).length,
groups: (patternStr.match(/\(/g) || []).length,
alternations: (patternStr.match(/\|/g) || []).length,
backtracking: 0,
complexity: 'LOW'
};
// Estimate backtracking potential
metrics.backtracking = metrics.quantifiers * metrics.groups;
// Calculate complexity
if (metrics.backtracking > 20 || metrics.groups > 10) {
metrics.complexity = 'HIGH';
} else if (metrics.backtracking > 10 || metrics.groups > 5) {
metrics.complexity = 'MEDIUM';
}
return metrics;
}
/**
* Measure regex execution time
*/
measureExecutionTime(regex, input) {
const start = process.hrtime.bigint();
try {
regex.test(input);
const end = process.hrtime.bigint();
const duration = Number(end - start) / 1000000; // Convert to milliseconds
return {
success: true,
duration,
input: input.substring(0, 50) + (input.length > 50 ? '...' : '')
};
} catch (error) {
return {
success: false,
error: error.message
};
}
}
/**
* Test regex with various inputs
*/
testRegexSafety(regex) {
const testInputs = [
'a'.repeat(10),
'a'.repeat(50),
'a'.repeat(100),
'a'.repeat(500),
'a'.repeat(1000),
'x'.repeat(100) + 'y',
'1'.repeat(100),
' '.repeat(100),
'abc'.repeat(50)
];
const results = [];
let maxDuration = 0;
let suspicious = false;
for (const input of testInputs) {
const result = this.measureExecutionTime(regex, input);
results.push(result);
if (result.success && result.duration > maxDuration) {
maxDuration = result.duration;
}
// If execution time increases exponentially, it's suspicious
if (result.success && result.duration > 100) {
suspicious = true;
}
}
return {
maxDuration,
suspicious,
results: results.filter(r => r.success)
};
}
/**
* Scan code for dangerous regex patterns
*/
scanCode(content) {
const findings = [];
// Find regex patterns in code
const regexPatterns = [
// JavaScript regex literals
/\/([^\/\n]+)\/([gimuy]*)/g,
// new RegExp()
/new\s+RegExp\s*\(\s*['"]([^'"]+)['"]/g
];
regexPatterns.forEach(pattern => {
let match;
while ((match = pattern.exec(content)) !== null) {
try {
const regexStr = match[1];
const flags = match[2] || '';
const regex = new RegExp(regexStr, flags);
const danger = this.isDangerous(regex);
const complexity = this.analyzeComplexity(regex);
if (danger.dangerous || complexity.complexity === 'HIGH') {
findings.push({
pattern: regex.toString(),
line: content.substring(0, match.index).split('\n').length,
dangerous: danger.dangerous,
reason: danger.reason,
complexity: complexity.complexity,
metrics: complexity
});
}
} catch (error) {
// Invalid regex, skip
}
}
});
return findings;
}
/**
* Generate ReDoS report
*/
generateReport(findings) {
return {
totalPatterns: findings.length,
dangerous: findings.filter(f => f.dangerous).length,
highComplexity: findings.filter(f => f.complexity === 'HIGH').length,
mediumComplexity: findings.filter(f => f.complexity === 'MEDIUM').length,
issues: findings.map(f => ({
pattern: f.pattern,
line: f.line,
risk: f.dangerous ? 'HIGH' : f.complexity,
reason: f.reason || `${f.complexity} complexity regex`
}))
};
}
/**
* Safe regex execution wrapper
* Now uses VM sandbox by default for better security
*/
safeExec(regex, input, operation = 'test') {
if (!this.config.ENABLE_REDOS_PROTECTION) {
// Protection disabled, execute normally
return operation === 'test' ? regex.test(input) : input.match(regex);
}
try {
// Check if regex is dangerous
const danger = this.isDangerous(regex);
if (danger.dangerous) {
throw new ReDoSError(`Dangerous regex pattern detected: ${danger.reason}`);
}
// Execute with VM sandbox (more secure than setTimeout)
if (operation === 'test') {
return this.testWithVMSandbox(regex, input);
} else {
return this.matchWithVMSandbox(regex, input);
}
} catch (error) {
if (error instanceof ReDoSError) {
throw error;
}
throw new ReDoSError(`Regex execution failed: ${error.message}`);
}
}
/**
* Safe async regex execution wrapper (for backward compatibility)
*/
async safeExecAsync(regex, input, operation = 'test') {
if (!this.config.ENABLE_REDOS_PROTECTION) {
// Protection disabled, execute normally
return operation === 'test' ? regex.test(input) : input.match(regex);
}
try {
// Check if regex is dangerous
const danger = this.isDangerous(regex);
if (danger.dangerous) {
throw new ReDoSError(`Dangerous regex pattern detected: ${danger.reason}`);
}
// Execute with timeout (Promise-based for async)
if (operation === 'test') {
return await this.testWithTimeout(regex, input);
} else {
return await this.matchWithTimeout(regex, input);
}
} catch (error) {
if (error instanceof ReDoSError) {
throw error;
}
throw new ReDoSError(`Regex execution failed: ${error.message}`);
}
}
}
module.exports = ReDoSProtector;
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