COMMON ATTACK PATTERN ENUMERATION AND CLASSIFICATIONLive MITRE record

CAPEC-229

Serialized Data Parameter Blowup

This attack exploits certain serialized data parsers (e.g., XML, YAML, etc.) which manage data in an inefficient manner. The attacker crafts an serialized data file with multiple configuration parameters in the same dataset. In a vulnerable parser, this results in a denial of service condition where CPU resources are exhausted because of the parsing algorithm. The weakness being exploited is tied to parser implementation and not language specific.

Abstraction

Detailed

Typical severity

High

Likelihood of attack

High

Understand the attack

What is this attack pattern?

This attack exploits certain serialized data parsers (e.g., XML, YAML, etc.) which manage data in an inefficient manner. The attacker crafts an serialized data file with multiple configuration parameters in the same dataset. In a vulnerable parser, this results in a denial of service condition where CPU resources are exhausted because of the parsing algorithm. The weakness being exploited is tied to parser implementation and not language specific.

Execution flow

How does the attack proceed, step by step?

1

Explore

Survey the target

Using a browser or an automated tool, an attacker records all instances of web services to process requests using serialized data.

Techniques used

  • Use an automated tool to record all instances of URLs to process requests from serialized data.
  • Use a browser to manually explore the website and analyze how the application processes requests using serialized data.
2

Exploit

Launch a Blowup attack

The attacker crafts malicious messages that contain multiple configuration parameters in the same dataset.

Techniques used

  • Send the malicious crafted message containing the multiple configuration parameters to the target URL, causing a denial of service.

Requirements

What does the attack require?

Prerequisites

  • The server accepts input in the form of serialized data and is using a parser with a runtime longer than O(n) for the insertion of a new configuration parameter in the data container.(examples are .NET framework 1.0 and 1.1)

Skills required

Not stated in the MITRE record.

Resources required

Not stated in the MITRE record.

Defence

How is it prevented and mitigated?

1
This attack may be mitigated completely by using a parser that is not using a vulnerable container.
2
Mitigation may limit the number of configuration parameters per dataset.

Real world

MITRE example instances

Example instance 1Detail
In this example, assume that the victim is running a vulnerable parser such as .NET framework 1.0. This results in a quadratic runtime of O(n^2). <?xml version="1.0"?> <foo aaa="" ZZZ="" ... 999="" /> A document with n attributes results in (n^2)/2 operations to be performed. If an operation takes 100 nanoseconds then a document with 100,000 operations would take 500s to process. In this fashion a small message of less than 1MB causes a denial of service condition on the CPU resources.
Example instance 2Detail
A YAML bomb leverages references within a YAML file to create exponential growth in memory requirements. By creating a chain of keys whose values are a list of multiple references to the next key in the chain, the amount of memory and processing required to handle the data grows exponentially. This may lead to denial of service or instability resulting from excessive resource consumption.
CAPEC-229: Serialized Data Parameter Blowup — DayBreach Saldırı Sözlüğü · DayBreach