XXEhyökkäys

XXEhyökkäys, or XML External Entity attack, is a type of security vulnerability that can occur in applications that parse XML input. When an application is vulnerable to an XXE attack, an attacker can interfere with the processing of XML data. This can happen when XML input containing a reference to an external entity is processed by a poorly configured XML parser. The external entity can then be used to read arbitrary files on the server, make network requests, or even cause denial-of-service conditions.

The core of an XXE attack lies in the XML specification's support for external entities. These entities allow XML documents to reference content from outside the document itself, such as from a local file or a remote URL. If an application does not properly validate or disable these external entity references, an attacker can craft malicious XML input that exploits this feature. For example, an attacker might include a reference to a local file like `/etc/passwd`, causing the application to retrieve and potentially disclose the contents of that file to the attacker.

Preventing XXE attacks involves configuring XML parsers to disable external entity resolution. This is often achieved through specific parser settings or by using secure coding practices that sanitize or reject XML input containing such references. Developers should always be aware of the XML parsing libraries they use and ensure they are configured securely, especially when dealing with untrusted user input. Regular security audits and penetration testing can also help identify and mitigate XXE vulnerabilities.