Improper Restriction of XML External Entity Reference, XML Injection (aka Blind XPath Injection) vulnerability in Apache Software Foundation Apache Ivy.This issue affects any version of Apache Ivy prior to 2.5.2.
When Apache Ivy prior to 2.5.2 parses XML files - either its own configuration, Ivy files or Apache Maven POMs - it will allow downloading external document type definitions and expand any entity references contained therein when used.
This can be used to exfiltrate data, access resources only the machine running Ivy has access to or disturb the execution of Ivy in different ways.
Starting with Ivy 2.5.2 DTD processing is disabled by default except when parsing Maven POMs where the default is to allow DTD processing but only to include a DTD snippet shipping with Ivy that is needed to deal with existing Maven POMs that are not valid XML files but are nevertheless accepted by Maven. Access can be be made more lenient via newly introduced system properties where needed.
Users of Ivy prior to version 2.5.2 can use Java system properties to restrict processing of external DTDs, see the section about JAXP Properties for External Access restrictions inside Oracles Java API for XML Processing (JAXP) Security Guide.
The product processes an XML document that can contain XML entities with URIs that resolve to documents outside of the intended sphere of control, causing the product to embed incorrect documents into its output.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Ivy | Apache | * | 2.5.2 (excluding) |
XML documents optionally contain a Document Type Definition (DTD), which, among other features, enables the definition of XML entities. It is possible to define an entity by providing a substitution string in the form of a URI. The XML parser can access the contents of this URI and embed these contents back into the XML document for further processing. By submitting an XML file that defines an external entity with a file:// URI, an attacker can cause the processing application to read the contents of a local file. For example, a URI such as “file:///c:/winnt/win.ini” designates (in Windows) the file C:\Winnt\win.ini, or file:///etc/passwd designates the password file in Unix-based systems. Using URIs with other schemes such as http://, the attacker can force the application to make outgoing requests to servers that the attacker cannot reach directly, which can be used to bypass firewall restrictions or hide the source of attacks such as port scanning. Once the content of the URI is read, it is fed back into the application that is processing the XML. This application may echo back the data (e.g. in an error message), thereby exposing the file contents.