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DOM-Based cross-site scripting (XSS)

Description​

The web application generates dynamic web content from the client side without validating the origin of the potentially malicious data.

Impact​

Generate web pages that could contain malicious scripts injected into untrusted data.

Recommendation​

Perform server-side and client-side input data validation to avoid the most common script injection attacks.

Threat​

Unauthorized attacker from the Internet.

Expected Remediation Time​

⌚ 90 minutes.

Score​

Default score using CVSS 3.1. It may change depending on the context of the vulnerability.

Base​

  • Attack vector: N
  • Attack complexity: L
  • Privileges required: N
  • User interaction: R
  • Scope: C
  • Confidentiality: L
  • Integrity: L
  • Availability: N

Temporal​

  • Exploit code madurity: X
  • Remediation level: X
  • Report confidence: X

Result​

  • Vector string: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N/E:X/RL:X/RC:X
  • Score:
    • Base: 6.1
    • Temporal: 6.1
  • Severity:
    • Base: Medium
    • Temporal: Medium

Code Examples​

Compliant code​

The application performs server side validation of all user inputs

var search = document.getElementById('search').value;
var results = document.getElementById('results');
results.innerHTML = "You searched for:" + verifyData(search);
function verifyData(str){
  return String(str).replace("ValidRegex");
}
//Server side validation should also be included in the code

Non compliant code​

The application takes user input without validating it on the server side

var search = document.getElementById('search').value;
var results = document.getElementById('results');
results.innerHTML = "You searched for:" + search;

Requirements​