An attacker used XSS to compromise a web server. Which of the following solutions could have been used to prevent this attack?

A Web Application Firewall (WAF) is specifically designed to protect web applications

from various attacks, including Cross-Site Scripting (XSS). It operates by inspecting

HTTP/S traffic and applying a set of rules to identify and block malicious payloads,

such as XSS scripts, before they reach the web server. WAFs are positioned in front of

web servers to filter out these threats.

A. NGFW (Next-Generation Firewall): While NGFWs offer advanced features like deep

packet inspection and application awareness, they primarily focus on network layer and

general application threats. A WAF is more specialized for web application vulnerabilities

like XSS.

B. UTM (Unified Threat Management): A UTM device consolidates multiple security

functions. While it might include some web filtering capabilities, it generally lacks the

depth and specificity of a dedicated WAF for mitigating sophisticated XSS attacks.

D. NAC (Network Access Control): NAC solutions are focused on enforcing security

policies for devices connecting to a network (e.g., ensuring antivirus is updated). They do

not inspect web traffic content to prevent XSS attacks.

OWASP (Open Web Application Security Project) - Web Application Firewall: "A

web application firewall (WAF) is an application firewall for HTTP applications. It

applies a set of rules to an HTTP conversation. Generally, these rules cover common

attacks such as cross-site scripting (XSS) and SQL injection."

URL: https://owasp.org/www-community/Web_Application_Firewall

Specific Location: Definition in the introductory paragraph.

NIST Special Publication 800-95: Guide to Secure Web Services: While not

exclusively about WAFs, it discusses the importance of input validation to prevent XSS

(Section 3.3.1) and mentions firewalls as a layer of defense. WAFs are a specialized

type of firewall for this purpose. Section 5.4 mentions "XML Firewalls" which are akin to

WAFs for XML-based web services, capable of deep content inspection.

URL: https://nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication800-95.pdf

Specific Location: Section 3.3.1 (Input Validation), Section 5.4 (XML Firewalls and

Guards).

Cloudflare - What is a WAF? | Web Application Firewall explained: "A WAF protects

web applications by filtering, monitoring, and blocking malicious HTTP/S traffic traveling

to the web application, and prevents unauthorized data from leaving the app. It does

this by adhering to a set of policies that help determine what traffic is malicious and

what traffic is safe... WAFs can come in the form of software, an appliance, or delivered

as-a-service. Policies can be customized to meet the unique needs of the web

application or set of web applications. Many WAFs are able to update policies

automatically by learning from traffic. While many WAFs protect against common

attacks like cross-site scripting (XSS)..."

URL: https://www.cloudflare.com/learning/ddos/glossary/web-application-firewall- waf/

Specific Location: Paragraphs 1 and 2.

AWS Documentation - What Is AWS WAF?: "AWS WAF is a web application firewall

that helps protect your web applications or APIs against common web exploits and bots

that may affect availability, compromise security, or consume excessive resources.

AWS WAF gives you control over how traffic reaches your applications by enabling you

to create security rules that control bot traffic and block common attack patterns, such

as SQL injection or cross-site scripting (XSS)."

URL: https://docs.aws.amazon.com/waf/latest/developerguide/what-is-aws-waf.html

Specific Location: First paragraph.

Microsoft Azure - What is Azure Web Application Firewall (WAF)?: "Azure Web

Application Firewall (WAF) on Azure Application Gateway provides centralized protection

of your web applications from common exploits and vulnerabilities. Web applications are

increasingly targeted by malicious attacks that exploit commonly known vulnerabilities

such as SQL injection and cross-site scripting."

URL: https://learn.microsoft.com/en-us/azure/web-application-firewall/ag/ag- overview

Specific Location: First paragraph.