XML-based applications must mitigate DoS attacks by using XML filters, parser options, or gateways.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-70237	APSC-DV-002390	SV-84859r1_rule		Medium

Description
DoS is a condition when a resource is not available for legitimate users. When this occurs, the organization either cannot accomplish its mission or must operate at degraded capacity. XML-based applications are susceptible to DoS attacks due to the nature of XML parsing being processor intensive and complicated. Best practice for parsing XML to avoid DoS include: - Using a proven XML parser - Using an XML gateway that provides DoS protection - Using parser options that provide limits on recursive payloads, oversized payloads, and entity expansion. This requirement addresses the configuration of applications to mitigate the impact of DoS attacks that have occurred or are ongoing on application availability. For each application, known and potential DoS attacks must be identified and solutions for each type implemented. A variety of technologies exist to limit or, in some cases, eliminate the effects of DoS attacks (e.g., limiting processes or restricting the number of sessions the application opens at one time). Employing increased capacity and bandwidth, combined with service redundancy, may reduce the susceptibility to some DoS attacks.

Description

DoS is a condition when a resource is not available for legitimate users. When this occurs, the organization either cannot accomplish its mission or must operate at degraded capacity. XML-based applications are susceptible to DoS attacks due to the nature of XML parsing being processor intensive and complicated. Best practice for parsing XML to avoid DoS include: - Using a proven XML parser - Using an XML gateway that provides DoS protection - Using parser options that provide limits on recursive payloads, oversized payloads, and entity expansion. This requirement addresses the configuration of applications to mitigate the impact of DoS attacks that have occurred or are ongoing on application availability. For each application, known and potential DoS attacks must be identified and solutions for each type implemented. A variety of technologies exist to limit or, in some cases, eliminate the effects of DoS attacks (e.g., limiting processes or restricting the number of sessions the application opens at one time). Employing increased capacity and bandwidth, combined with service redundancy, may reduce the susceptibility to some DoS attacks.

STIG	Date
Application Security and Development Security Technical Implementation Guide	2017-03-20

Details

Check Text ( C-70713r1_chk )
Review the application architecture documentation and interview the application administrator to identify what steps have been taken to protect the XML aspect of the application from DoS attacks. If the application does not contain or utilize XML, the requirement is not applicable. Ask the application administrator to demonstrate how the application is configured to provide the following protections: - Validation against recursive payloads - Validation against oversized payloads - Protection against XML entity expansion - Validation against overlong element names - Optimized configuration for maximum message throughput If the application administrator cannot demonstrate how these protections are implemented either within the application itself or by third-party tools or utilities like an XML gateway, this is a finding.

Check Text ( C-70713r1_chk )

Review the application architecture documentation and interview the application administrator to identify what steps have been taken to protect the XML aspect of the application from DoS attacks.

If the application does not contain or utilize XML, the requirement is not applicable.

Ask the application administrator to demonstrate how the application is configured to provide the following protections:

- Validation against recursive payloads
- Validation against oversized payloads
- Protection against XML entity expansion
- Validation against overlong element names
- Optimized configuration for maximum message throughput

If the application administrator cannot demonstrate how these protections are implemented either within the application itself or by third-party tools or utilities like an XML gateway, this is a finding.

Fix Text (F-76473r1_fix)
Implement: - Validation against recursive payloads - Validation against oversized payloads - Protection against XML entity expansion - Validation against overlong element names - Optimized configuration for maximum message throughput in order to ensure DoS attacks against web services are limited.