Vulnerable XML Service

XML Message

<doc><n1>5</n1><n2>2</n2><div>5</div><mod>2</mod></doc>

XSLT Document

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
    <xsl:template match="doc">
        <HTML>
        
            <H1>Test for mod.</H1>
            <H2>XSLT Version:<xsl:value-of select="system-property('xsl:version')"/></H2>
            <HR/>
            <P>Should say "1": <xsl:value-of select="5 mod 2"/></P>
            <P>Should say "1": <xsl:value-of select="n1 mod n2"/></P>
            <P>Should say "-1": <xsl:value-of select="div mod mod"/></P>
            <P>
                <xsl:value-of select="div or ((mod)) | or"/>
            </P>
        </HTML>
    </xsl:template>
</xsl:stylesheet>

Result

XPath Training Exercises

Learn XPath by selecting specific nodes in XML documents. Your goal is to write an XPath expression that selects nodes containing FLAG values.
Each node must by selected with the correct type (element, text, or attribute), as indicated in the FLAG name suffix.

⚠️ Challenge: Each exercise has a maximum character limit for your XPath expression!

Select Exercise:

Exercise 1 Easy Exercise 2 Easy-Medium Exercise 3 Medium Exercise 4 Hard Exercise 5 Very Hard Exercise 6 Master

XML Document (readonly):

<library>
  <book>Other Book</book>
  <book>FLAG_XML_XPATH1_ELEMENT</book>
  <book>Another Book</book>
</library>

Your XPath Expression:

0 / - characters

Execution Result:

💡 General XPath Hints:

Select element: //elementName or /root/elementName
Select text node: //elementName/text()
Select attribute: //elementName/@attributeName
Filter by position: //elementName[5] (fifth element)
Filter by attribute: //elementName[@attr='value']
Union operator: xpath1 | xpath2 (combine multiple selections)
Namespace prefix: Use the prefix shown in the XML (e.g., //ns:element)

Message to sign:

<?xml version="1.0" encoding="UTF-8"?>
<AuthenticationToken id="0">
    <security id="1">
        <timestamp>01.04.2015:12:00:00</timestamp>
        <nonce>2dfgjkdft834gtg3</nonce>
        <destination>http://serviceA.com</destination>
    </security>
    <apiCall id="2">
        <user id="3">normalUser</user>
        <operations>getTime()</operations>
    </apiCall>
</AuthenticationToken>

References:

Reference IDs with a # or use xpath. Multiple references possibile with ;.
Examples: "#1", "#1;#2", "//*[@id=3]", "#1;//*[@id=3]"

Canocalization:

Inclusive, with Comments Inclusive, without Comments

Exclusive, with Comments Exclusive, without Comments

Type:

Enveloped Enveloping Detached

Signing Result:

Message to verify:

Verifier:

XML Signature Wrapping Attacks (Verifiers 1-4)

Description: Manipulate the signed SEPA message and execute a transaction to the "attacker" with IBAN "DE66 6666 6666 6666" over 6666 EUR.

Verifier 1 Medium Download Schema Verifier 2 Easy Download Schema Verifier 3 Medium-Hard Download Schema Verifier 4 Easy-Medium Download Schema

💡 Hints for XML Signature Wrapping Attacks:

Which part(s) of the XML document are used as input for the DigestValue computation?
Which type of signature is applied? (Enveloped, Enveloping, Detached)
Which part(s) of the XML document are used as input for the SignatureValue computation?
You can investiagte the XML Schema. Are there xs:any elements? If not, can the application handle multiple transactions at once?

Analyze Broken Message (Verifiers 5-6)

Description: The message was generated correctly and not manipulated after signing. Nevertheless, the verification fails. Your task is to determine and explain the problem with the signed message.

Verifier 5 Download Schema Verifier 6 Download Schema

💡 Hints for Analyzing Broken Messages:

There is no flag to get here. This task is about understanding XML Signature Processing.
Which part(s) of the XML document are used as input for the DigestValue computation?
Which type of signature is applied? (Enveloped, Enveloping, Detached)
Which part(s) of the XML document are used as input for the SignatureValue computation?
You can compare the messages of verifier 5 and 6 to each other. They use the same verification logic, but only verifier 5 fails. Why?