What are XXE Attacks

Untrusted external references inside an XML file are evaluated by XML processors in some web applications. These references allow attackers to leverage external parameter entities to reveal information from configuration files, which they may use to compromise the system further.
Because these attacks are carried out by parsing XML inputs in a program, attackers can use them to gain access to other connected systems, resulting in application downtime and data loss. As a result, it is critical to comprehend the nature of these attacks and how they might be avoided. 

What are XML External Entities?
XML external entities have values that are loaded outside of the Document Type Declaration (DTD). Hackers can intercept data traveling to the server and inject harmful payloads if the parser that analyzes external entities is poorly configured.

What are the best practices to prevent XXE vulnerabilities?

While disabling the resolution of external entities is never enough, there are several ways to thwart XXE assaults successfully. Techniques that businesses may use to protect themselves from attacks involving External XML Entities:

  • Use simple data formats
  • Use updated XML processes and libraries
  • Disable Document Type Definition and XXE in all XML parsers
  • Use whitelisting for Server-Side Input Validation
  • SAST tools to identify XXE attack surfaces in source code

How potentially dangerous are XML external entities?

ccording to OWASP and the Common Weakness Enumeration (CWE) database, XXE attacks are among the top security concerns since they result in request forgery, denial of service, and the leaking of sensitive data. Because it may be carried out through various attack routes and is still regarded as a novel attack technique due to a lack of awareness among security teams, XXE attacks are widespread.

What is an XXE vulnerability scanner?

An XXE scanner tests your online application security posture while saving time and money for developers. In addition, an XXE scanner probes for XML External Entity vulnerabilities by executing security checks in your online application.

Note: To scan for XXE, you must own the site and have the proper admin access. You’ll need the authorization to run this scanner since the XML External Entity tool can generate various HTTP Requests that could be identified as attacks (albeit they’re entirely safe).

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Why should I test for XML External Entity?

When you test for XXE vulnerabilities, you are closer to preventing these dangerous attacks that permit hackers to acquire customers’ data such as passwords, credit cards, and email information.
In most cases, an application is deemed vulnerable to XXE assaults because of the following scenarios:

  • XML documents are parsed by a web application: If an application accepts XML documents as input or uploads them, attackers can modify the XML document and access system files and configuration data.
  • Document Type Declaration (DTD) Identifier Contaminated Data: If the XML parser supports DTD processing, attackers can launch a billion laughs assault, which is a sort of Denial-of-Service attack based on recursive entities.
  • The DTD is validated and processed by the XML Processor: Attackers can use XML documents to access local resources and prevent them from providing data if DTD validation is enabled for XML processing. Furthermore, if the DTD’s XML Parser resolves foreign entities.

How do I detect XXE vulnerabilities?

With Veracode Dynamic Analysis, you can set up and start scanning for XXE vulnerabilities in less than 10 minutes.

  • You are just one click away from discovering your XXE vulnerability: We scan your web application in just a few minutes and provide a report with all vulnerabilities found.
  • An excellent support team of security: We verify your test for XML External Entity to ensure you are correctly setting up our vulnerability scanning tool. 
  • Not just XXE vulnerability: Mitigate all Top 10 OWASP vulnerabilities. You’ll get precisely the types of attacks you are exposed to and the risk levels they have.


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