External Entity Processing allows for XML parsing with the involvement of external entities. However, when this functionality is enabled without
proper precautions, it can lead to a vulnerability known as XML External Entity (XXE) attack.
What is the potential impact?
Exposing sensitive data
One significant danger of XXE vulnerabilities is the potential for sensitive data exposure. By crafting malicious XML payloads, attackers can
reference external entities that contain sensitive information, such as system files, database credentials, or configuration files. When these
entities are processed during XML parsing, the attacker can extract the contents and gain unauthorized access to sensitive data. This poses a severe
threat to the confidentiality of critical information.
Exhausting system resources
Another consequence of XXE vulnerabilities is the potential for denial-of-service attacks. By exploiting the ability to include external entities,
attackers can construct XML payloads that cause resource exhaustion. This can overwhelm the system’s memory, CPU, or other critical resources, leading
to system unresponsiveness or crashes. A successful DoS attack can disrupt the availability of services and negatively impact the user experience.
Forging requests
XXE vulnerabilities can also enable Server-Side Request Forgery (SSRF) attacks. By leveraging the ability to include external entities, an attacker
can make the vulnerable application send arbitrary requests to other internal or external systems. This can result in unintended actions, such as
retrieving data from internal resources, scanning internal networks, or attacking other systems. SSRF attacks can lead to severe consequences,
including unauthorized data access, system compromise, or even further exploitation within the network infrastructure.
