How does a XML Flood attack work?

It typically unfolds over 3 phases. It begins with: [Survey the target] Using a browser or an automated tool, an attacker records all instance of web services to process XML requests.

How do you prevent CAPEC-528?

Design: Build throttling mechanism into the resource allocation. Provide for a timeout mechanism for allocated resources whose transaction does not complete within a specified interval.

What weaknesses does CAPEC-528 target?

CAPEC-528 exploits 1 CWE weakness, including CWE-770 (Allocation of Resources Without Limits or Throttling).

How severe is CAPEC-528?

MITRE rates CAPEC-528 as Medium severity with low likelihood of attack.

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Standard attack pattern

Draft

CAPEC-528: XML Flood

Also known as: XML Denial of Service (XML DoS)

An adversary may execute a flooding attack using XML messages with the intent to deny legitimate users access to a web service. These attacks are accomplished by sending a large number of XML based requests and letting the service attempt to parse each one. In many cases this type of an attack will result in a XML Denial of Service (XDoS) due to an application becoming unstable, freezing, or crashing.

Last updated June 1, 2026

Medium

Typical severity

Per MITRE

Low

Likelihood of attack

Per MITRE

1

Related weaknesses

CWEs this targets

Standard

Abstraction

MITRE classification

Overview

XDoS is most closely associated with web services, SOAP, and Rest, because remote service requesters can post malicious XML payloads to the service provider designed to exhaust the service provider's memory, CPU, and/or disk space. The main weakness in XDoS is that the service provider generally must inspect, parse, and validate the XML messages to determine routing, workflow, security considerations, and so on. It is exactly these inspection, parsing, and validation routines that XDoS targets. This attack exploits the loosely coupled nature of web services, where the service provider has little to no control over the service requester and any messages the service requester sends.

How the attack works

The phases an attacker typically follows to carry out this attack.

Step 1
Explore
[Survey the target] Using a browser or an automated tool, an attacker records all instance of web services to process XML requests.
- Use an automated tool to record all instances of URLs to process XML requests.
- Use a browser to manually explore the website and analyze how the application processes XML requests.
Step 2
Experiment
An adversary crafts input data that may have an adverse effect on the operation of the web service when the XML data sent to the service.
Step 3
Exploit
[Launch a resource depletion attack] The attacker delivers a large number of XML messages to the target URLs found in the explore phase at a sufficiently rapid rate. It causes denial of service to the target application.
- Send a large number of crafted XML messages to the target URL.

What the attacker needs

Prerequisites

The target must receive and process XML transactions.
An adverssary must possess the ability to generate a large amount of XML based messages to send to the target service.

Skills required

Low skill: Denial of service

Consequences

What a successful CAPEC-528 attack can achieve.

Resource Consumption

Affects: Availability

How to mitigate it

Defenses that reduce the risk of CAPEC-528.

Design: Build throttling mechanism into the resource allocation. Provide for a timeout mechanism for allocated resources whose transaction does not complete within a specified interval.
Implementation: Provide for network flow control and traffic shaping to control access to the resources.

How to detect it

Indicators that this attack may be underway.

A large amount of data is passed to the XML parser possibly making it crash or otherwise unavailable to end users.

Examples

Consider the case of attack performed against the createCustomerBillingAccount Web Service for an online store. In this case, the createCustomerBillingAccount Web Service receives a huge number of simultaneous requests, containing nonsense billing account creation information (the small XML messages). The createCustomerBillingAccount Web Services may forward the messages to other Web Services for processing. The application suffers from a high load of requests, potentially leading to a complete loss of availability the involved Web Service.

Terminology & mappings

Alternate terms

XML Denial of Service (XML DoS)

Mapped taxonomies

ATTACK: Endpoint Denial of Service:Service Exhaustion Flood (1499.002)
ATTACK: Network Denial of Service:Direct Network Flood (1498.001)

Frequently asked questions

Common questions about CAPEC-528.

What is CAPEC-528?: An adversary may execute a flooding attack using XML messages with the intent to deny legitimate users access to a web service. These attacks are accomplished by sending a large number of XML based requests and letting the service attempt to parse each one. In many cases this type of an attack will result in a XML Denial of Service (XDoS) due to an application becoming unstable, freezing, or crashing.
How does a XML Flood attack work?: It typically unfolds over 3 phases. It begins with: [Survey the target] Using a browser or an automated tool, an attacker records all instance of web services to process XML requests.
How do you prevent CAPEC-528?: Design: Build throttling mechanism into the resource allocation. Provide for a timeout mechanism for allocated resources whose transaction does not complete within a specified interval.
What weaknesses does CAPEC-528 target?: CAPEC-528 exploits 1 CWE weakness, including CWE-770 (Allocation of Resources Without Limits or Throttling).
How severe is CAPEC-528?: MITRE rates CAPEC-528 as Medium severity with low likelihood of attack.

References

Attack-pattern data is sourced from the MITRE CAPEC catalog (v3.9). Weakness associations link to the corresponding CWE entries on RadicalNotion.AI.

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