Given the proliferation of threats these days and the fact that many of them can stem from exploiting device weaknesses, scanning for vulnerabilities has become a must. But why scan for cross-site scripting (XSS) vulnerabilities in particular? The quick answer? XSS currently ranks number 1 in MITRE’s 2024 CWE Top 25 Most Dangerous Software Weaknesses list.
Before we identify the best defenses against XSS vulnerability exploitation available, though, let us learn more about the weakness.
What Is an XSS Vulnerability?
A XSS vulnerability is a web security flaw that lets attackers inject malicious scripts into trusted websites. These scripts are then executed by victims’ browsers and can result in several harmful actions. The threat actors can, for instance, steal sensitive information like session cookies, take over user accounts, or redirect users to phishing sites. The vulnerability stems from applications that use untrusted user inputs in their outputs without properly validating or sanitizing them.
What Risks Do XSS Vulnerabilities Pose?
Successful exploitation of an XSS vulnerability can pose several nasty repercussions, which we named below.
- Data theft: Threat actors can steal any sensitive information the victim has access to like login credentials, cookies, and other personal data. They can use a malicious script to read session cookies and send them to a remote server under their control. They can then impersonate the user later on.
- Account and session hijacking: Stolen session cookies and tokens in attackers’ possession can let them hijack a users’ active sessions to gain unauthorized access to their accounts. Things get much worse if the compromised users have administrative privileges on corporate networks. The threat actors can gain full control over entire applications and all its data.
- Malware injection: Attackers can also use XSS to force victims’ browsers to download and run malware. After that, all bets are off. The malware can be of any kind—ransomware, spyware, or a malicious script that turns the infected computers into bots.
- Phishing and social engineering: Threat actors can also manipulate vulnerable sites for their phishing campaigns. They can, for instance, use the sites to redirect users to phishing pages designed to trick users into giving out credentials or other confidential information.
- Defacement and misinformation: In other cases, attackers can use malicious scripts to alter a site’s content in defacement attacks. This can damage an organization’s reputation and spread misinformation that may adversely affect its stock price or public trust.
The British Airways breach in 2018 could be one of the most infamous XSS attacks to date. The threat actors abused an XSS vulnerability to inject a credit card-skimming script into the airline’s payment page, harvesting personal and financial details from thousands of its customers.
How Does an XSS Vulnerability Scanner Work?
Using an XSS vulnerability scanner is the best way to prevent attacks. It works by mimicking attackers to automatically test web applications for flaws that can allow malicious script injection.
First, the scanner crawls target web applications to find out how it is structured and functions. It builds a map of site pages, features, and input fields. After that, the scanner sends specially crafted test requests or payloads to every possible attack entry point. These payloads contain malicious scripts designed to trigger an XSS vulnerability. It checks for different XSS types—reflected, stored, and Document Object Model (DOM)-based XSS. Then the scanner monitors the applications’ responses to check for successful payload execution. Finally, the scanner compiles the findings into a report for the security team. This report contains all the identified vulnerabilities, severity ratings, detailed explanations, and recommendations on fixing them.
How Can an XSS Vulnerability Scanner Help Users?
Scanning for vulnerabilities manually can be a chore—it takes a lot of time and effort to do so. Enter XSS vulnerability scanners, specialized must-have tools that automate the detection of persistent and widespread threats. In many cases, the tools can enable XSS vulnerability scanning from the onset—the software development life cycle—providing proactive, scalable, and cost-effective defenses against various client-side attacks.
Top 10 XSS Vulnerability Scanners
To avoid the huge hassle of manual vulnerability scanning, we thought a list of the best tools in the market can help.
1. Attaxion
Attaxion is an external attack surface management (EASM) tool that finds all of an organization’s web-facing assets to continuously uncover and reduce cyber risks. That said, it provides a real-time inventory of all Internet-facing assets, including their vulnerabilities, connections, and technologies.
The tool enables users to continuously get rid of pressing attack vectors in their ever-expanding digital perimeters; run fully automated security testing for web apps across their entire external attack surfaces; identify, assess, and continuously monitor for new third-party technologies and associated risks; gain insights into vendors’ security postures to avoid inherited cyber risks; and get rid of potential compliance issues by ensuring all external assets are cataloged and scanned for vulnerabilities.
Attaxion is ideal for organizations with small security teams. Learn more about the tool by requesting a demo or visiting their site. Try it free of charge or subscribe to any of these four plans:
- Starter: US$129 per month
- Plus: US$349 per month
- Business: US$949 per month
- Enterprise: Sales contact required
2. Burp Suite
Burp Suite is a web application security, testing, and scanning tool offered by PortSwigger. It offers hands-on security testers a tool they can have faith in and enjoy using.
The tool lets testers be at the forefront of web security testing with a toolkit powered by cutting-edge research. It has all the requirements for modern pentesting that uses advanced features to eliminate noise. Best of all, it simplifies documentation and remediation by producing reports for end users.
Burp Suite is ideal for pentesters. Know more about it by visiting the site. You can try it for free or purchase the tool for US$475.
3. Acunetix
Acunetix can help find and fix vulnerabilities that put organizations’ applications and application programming interfaces (APIs) at risk of attacks fast.
Like Attaxion, the tool automatically and continuously looks for web-facing assets. It then gives a risk score for each asset, calculated from 220 parameters. As such, users can save time while proactively gaining risk insights. The scores also let them focus on the most at-risk assets first.
Interested? Avail of their free demo or visit their site for more information. Acunetix offers three plans—Essentials, Professional, and Ultimate.
4. Invicti
Invicti hopes to make application security automatic by consolidating alerts, remediating risks with speed, and reporting incidents with confidence. It scans applications without flooding users with alerts. How? It gets rid of duplicates and false positives on the fly.
Like Attaxion and Acunetix, it provides risk scores that are automatically adjusted based on an organization’s threat Intelligence. All in all, it boasts of cutting through the noise, keeping up with development, and knowing where an organization stands in terms of safety.
Find out more about Invicti by visiting their site. Potential users can avail of one of three packages with custom pricing—Essentials, Professional, and Ultimate.
5. ZAP
Unlike the first four tools on our list, ZAP, short for “Zed Attack Proxy,” is an open-source tool that anyone can use free of charge.
The tool scans and analyzes systems for security issues. They are then subjected to attack simulations as part of pentesting. After that, they are subjected to end-user analysis and security testing. Then comes testing for the system code in search of security vulnerabilities.
ZAP is available for download at their site.
6. Tenable
Tenable touts that it lets users know where they are exposed to address critical risks. It enables active scanning and passive monitoring to provide unified visibility of all of an organization’s assets. It can address more than 85,000 vulnerabilities and combines vulnerability data, threat intelligence, and data science to compute risk scores that allow users to quickly assess risks and know which vulnerabilities to fix first.
Like the other paid solutions, users can try the tool free of charge by visiting their site. Three subscription options are available for a minimum of 100 assets. A 1-year subscription costs US$5,488. Potential subscribers can also opt for a 2- or 3-year subscription for US$10,701.60 and US$15,640.80, respectively.
7. Astra Security Suite
Astra Security is a platform that offers expert-led offensive pentests, penetration testing as a service (PTaaS), API, and cloud vulnerability scanning. It is useful for manual pentesting and vulnerability management. It utilizes an artificial intelligence (AI)-assisted engine and performs dynamic application security testing (DAST).
Interested users can visit their site to schedule a demo. Three options are available to potential customers:
- Pentest: US$5,999 per year
- Pentest Plus: US$9,999 per year
- Enterprise: Sales contact required
8. Intruder.io
Intruder.io claims to be able to stop breaches before they start. It discovers threats in real time and helps users prioritize attack surface weaknesses so they can focus on fixes that matter.
The tool discovers unknown assets across organizations, including subdomains, related domains, untracked APIs, login pages, and more. It can integrate with Amazon Web Services (AWS), Google Cloud, Cloudflare, and Azure accounts to detect new services as soon as they are exposed. It also minimizes organizations’ exposure windows and more.
For more information about Intruder.io, visit their site. The tool has four package options:
- Essential: US$149 per month
- Cloud: US$299 per month
- Pro: US$499 per month
- Enterprise: Custom pricing
9. InsightVM
InsightVM lets users stay ahead of modern threats by delivering comprehensive visibility and adversary-aware prioritization and streamlining remediation workflows. It identifies and closes critical vulnerabilities with agent and agentless scanning options supported by a unified vulnerability database. It also allows organizations to focus on weaknesses that matter most using a scoring model.
The tool provides unified vulnerability management aided by AI.
Interested? Visit their site. Check out their pricing options, too:
- US$2.19 a month for 250 assets per asset
- US$1.93 a month for 500 assets per asset
- US$1.79 a month for 750 assets per asset
- US$1.71 a month for 1,000 assets per asset
- US$1.62 a month for 1,250 assets per asset
10. VMDR
VMDR, short for “Vulnerability Management, Detection, and Response,” by Qualys boasts of accurately measuring, quantifying, and tracking risks related to vulnerabilities across assets and business units. It can communicate risks across teams, business units, and geographic locations using dashboards, reports, and IT service management (ITSM) tools. It also patches devices no matter where they are.
More information about the tool is available on their site. Pricing details, however, are not readily available. Interested parties may contact their sales team.
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Security experts believe XSS vulnerability exploitation will continue to ensue because it works. As a result, industry analysts predict that the web application vulnerability scanner market size will reach US$4.5 billion by 2033 at a compound annual growth rate (CAGR) of 16.5% from 2026 to 2033.
